Differentials

Common

Nonhemorrhagic volume losses

History

often older adults; may be a history of vomiting and diarrhea, prolonged period of illness, or diuretic use; burns; profound sweating; decreased oral intake; bronchorrhea or draining pleural effusion; history of or risk factors for diabetes insipidus; risk factors for diabetic ketoacidosis or hyperosmolar hyperglycemic state; may be fever; thirst; fatigue; dizziness on standing

Exam

hypotension may be profound if there is shock with decreasing level of consciousness; fever; tachycardia; weak pulse; dry mucous membranes; decreased skin turgor

1st investigation
  • basic test panel (CBC, serum electrolytes, blood glucose, serum LFTs, coagulation profile):

    elevated BUN and creatinine; normal, elevated or low serum sodium; low serum potassium (with diarrhea); elevated hematocrit; elevated WBC count (if infectious cause)

    More
  • ECG:

    sinus tachycardia, tachyarrhythmia

  • urinalysis:

    high specific gravity

Other investigations
  • ABG:

    prolonged diarrhea: low bicarbonate; prolonged vomiting: high bicarbonate

    More
  • random urine sodium:

    <20 mmol/L (<20 mEq/L)

    More
  • fractional excretion of sodium:

    <1%

    More
  • random urine creatinine:

    elevated

    More
  • random urine osmolality:

    >450 mmol/kg (>450 mOsm/kg)

  • stool culture:

    normal; may show growth of bacteria, toxins or parasites

    More
  • urine microscopy and culture:

    normal or evidence of bacterial growth

    More

Upper gastrointestinal bleed

History

history of nonsteroidal anti-inflammatory drugs use, often with concomitant corticosteroid use; may be history of peptic ulcer disease or chronic liver disease; upper abdominal pain (frequently absent in older adults); hematemesis; coffee ground emesis; fatigue, dizziness

Exam

hypotension may be profound if there is shock with decreasing level of consciousness; pallor, abdominal tenderness (usually upper abdomen); signs of chronic liver disease (e.g., palmar erythema, spider angiomata, petechiae, jaundice, hepatomegaly, ascites, muscle wasting, gynecomastia, pedal and ankle edema); rectal exam positive for melena

1st investigation
  • basic test panel (CBC, serum electrolytes, blood glucose, serum LFTs, coagulation profile, type and cross):

    normal or low Hb, elevated BUN:creatinine ratio; may be abnormal prothrombin time and prolonged INR

  • ECG:

    sinus tachycardia

  • upper gastrointestinal endoscopy:

    source of bleeding may be visualized

    More
Other investigations

    Lower gastrointestinal bleed

    History

    may be known history of inflammatory bowel disease or lower gastrointestinal tumor; melena; hematochezia; abdominal pain (left-sided in older adult suggests diverticular disease); fatigue; dizziness

    Exam

    hypotension may be profound if there is hemorrhagic shock with decreasing level of consciousness; may be blood on digital rectal exam; abdominal exam may be normal, or may be tenderness; patients with colonic tumor may have a palpable abdominal mass

    1st investigation
    • basic test panel (CBC, serum electrolytes, blood glucose, serum LFTs, coagulation profile, type and cross):

      normal or low Hb; elevated BUN:creatinine ratio; may be abnormal prothrombin time and prolonged INR

    • ECG:

      sinus tachycardia

    • colonoscopy:

      source of bleeding may be visualized (e.g., diverticulae, colonic angioma, polyps, evidence of inflammatory bowel disease or colonic tumor)

    • mesenteric angiography:

      the site of active bleeding may be seen[88]

    Other investigations

      Dialysis-induced hypotension

      History

      presence of hypotension during dialysis session; previous history of dialysis-induced hypotension; presence of other condition that may predispose to hypotension (e.g., intercurrent infective illness leading to dehydration); diabetes, large interdialytic weight gain, female sex and low body weight are risk factors for dialysis-induced hypotension

      Exam

      tachycardia; weak pulse; increased skin turgor; dry mucous membranes; signs of chronic renal failure (e.g., increased skin pigmentation)

      1st investigation
      • clinical exam:

        usually a clinical diagnosis

      • ECG:

        may be sinus tachycardia, evidence of tachyarrhythmia

      Other investigations
      • basic test panel (CBC, serum electrolytes, blood glucose, serum LFTs, coagulation profile):

        elevated BUN and creatinine; low or high serum sodium; elevated hematocrit

      Trauma

      History

      history of road traffic accident, fall, penetrating injury, blunt trauma

      Exam

      may be signs of external bleeding; open fracture; tender abdomen concealing intra-abdominal hemorrhage; decreased breath sounds and dullness to percussion on chest examination may indicate hemothorax; unstable pelvis if fractured; narrow pulse pressure

      1st investigation
      • CBC, type and cross:

        may be low or normal Hb

      • coagulation screen:

        serum PT, INR and PTT may be prolonged or elevated

      • x-ray trauma series:

        hemothorax if chest injury, widened mediastinum suggests aortic disruption, pelvic fractures if present

        More
      • Focused Assessment with Sonography for Trauma scan:

        positive if free fluid in the abdomen or pericardium is identified

        More
      • CT scan:

        may show blood in abdominal cavity

        More
      Other investigations
      • diagnostic peritoneal lavage:

        blood in the abdomen on drainage of fluid suggests intra-abdominal bleed

        More

      Acute coronary syndrome

      History

      history of risk factors for coronary artery disease (CAD) (e.g., smoking, hyperlipidemia, diabetes, family history of CAD); chest pain (often described as heavy or tight) radiating to arms, back, neck, or jaw; chest pain may be absent in older adults and people with diabetes; dyspnea; nausea; diaphoresis

      Exam

      hypotension may be profound if there is cardiogenic shock + decreasing level of consciousness; diaphoretic appearance; pallor; tachycardia; bradycardia; new abnormal pulse rhythm; distended jugular veins; other signs of heart failure (e.g., dyspnea, crackles at lung bases); new heart murmur

      1st investigation
      • ECG:

        ST segment elevation or depression, or T wave changes

      • basic test panel (CBC, serum electrolytes, blood glucose, serum LFTs, serum troponin, d-dimer, coagulation profile):

        elevated serum troponin

      • coronary angiogram:

        presence of thrombus with occlusion of the artery

      • chest x-ray:

        evidence of pulmonary congestion/pleural effusion if secondary heart failure, may show enlarged cardiac shadow

      Other investigations
      • fasting serum lipids (total cholesterol, LDL cholesterol, HDL cholesterol and triglycerides):

        variable

        More
      • fasting blood glucose:

        normal, or above normal range if diabetes detected

        More
      • echocardiogram:

        may demonstrate regional wall motion abnormality

      Acute heart failure

      History

      acute onset shortness of breath; orthopnea; may be history of known heart failure or of risk factors (e.g., recent myocardial infarction, valvular heart disease, hypertrophic cardiomyopathy, known bacterial endocarditis, rheumatic fever, or Marfan syndrome)

      Exam

      hypotension may be profound if there is cardiogenic shock plus decreasing level of consciousness; distended jugular veins; crackles at lung bases; new murmur; additional heart sounds; fever in endocarditis; mitral facies (mild cyanosis of lips/cheeks without clubbing) may be present if mitral stenosis is a causative factor; may be signs of Marfan syndrome (e.g., tall stature, wide arm span, high arched palate, arachnodactyly with positive thumb sign)

      1st investigation
      • ECG:

        nearly always abnormal; may show arrhythmias, ischemic ST and T wave changes

      • basic test panel (CBC, serum electrolytes, blood glucose, serum LFTs, serum troponin, d-dimer, coagulation profile):

        serum troponin: elevated in acute coronary ischemia; low Hb if anemia the cause; WBC count may be elevated

      • serum thyroid-stimulating hormone and free T4:

        abnormal if associated hypo- or hyperthyroidism

      • chest x-ray:

        cardiomegaly, pulmonary congestion, pleural effusion, valvular or pericardial calcification

      • echocardiogram:

        new valvular dysfunction (e.g., mitral regurgitation); endocarditis: may show vegetations

      Other investigations
      • B-type natriuretic peptide (BNP):

        >400 picogram/mL may be indicative of heart failure

        More
      • fasting serum lipids (total cholesterol, LDL cholesterol, HDL cholesterol and triglycerides):

        variable

      • blood cultures:

        endocarditis: positive cultures

      Dysrhythmia

      History

      more common in older patients; symptoms may be acute, chronic, or paroxysmal; palpitations; chest pain; syncope; dizziness; dyspnea; may be history of dysrhythmia, heart disease or heart failure

      Exam

      signs may be acute, chronic or paroxysmal; hypotension may be profound if there is cardiogenic shock + decreasing level of consciousness; tachycardia; bradycardia; irregular pulse; may have signs of heart failure (e.g., distended jugular veins, crackles at lung base, peripheral edema)

      1st investigation
      • ECG:

        dysrhythmia demonstrated

        More
      • basic test panel (CBC, serum electrolytes, blood glucose, serum LFTs, serum troponin, d-dimer, coagulation profile):

        may be low Hb, abnormal serum electrolytes

      • serum thyroid-stimulating hormone, free T4:

        thyroid-stimulating hormone and free T4 may be abnormal if hypo- or hyperthyroidism cause of dysrhythmia

      Other investigations
      • cardiac telemetry:

        dysrhythmia demonstrated

      • 24-hour ECG monitor:

        dysrhythmia demonstrated

      Acute pulmonary embolism

      History

      dyspnea; pleuritic chest pain (often absent in older adults); hemoptysis; palpitations; feeling of apprehension; may be history of recent immobilization (e.g., prolonged air flight, surgery), obesity, pregnancy/postpartum period, inherited thrombophilias, active malignancy, recent trauma/fracture, or history of deep vein thrombosis

      Exam

      hypotension may be profound if large pulmonary embolism (PE) but in other cases physical exam can be normal; may be tachypnea; pleural rub on chest auscultation; tachycardia; low oxygen saturations on pulse oximetry (may be transient); calf tenderness

      1st investigation
      • basic test panel (CBC, serum electrolytes, blood glucose, serum LFTs, serum troponin, d-dimer, coagulation profile):

        d-dimer: normal or elevated

        More
      • ABG:

        may be normal; hypoxia and hypocapnia suggestive of PE

      • ECG:

        tachycardia, new right axis deviation, new right bundle branch block, S wave in lead I, Q wave with T-wave inversion in lead III

        More
      • chest x-ray:

        band atelectasis, elevation of hemidiaphragm, prominent central pulmonary artery, oligemia at site of embolism

        More
      Other investigations
      • multi-detector computed tomography pulmonary angiography:

        direct visualization of thrombus in a pulmonary artery, appears as a partial or complete intraluminal filling defect

        More
      • ventilation/perfusion (V/Q) scan:

        normal, low, intermediate, and high probability; PE likely when an area of ventilation is not perfused

        More
      • transthoracic echocardiography:

        may show features indicating right ventricular strain/dysfunction

      • pulmonary angiography:

        demonstrates complete or incomplete filling defect in the pulmonary artery

        More
      • duplex ultrasound of femoral and calf veins:

        noncompressible leg veins

        More
      • serum thyroid-stimulating hormone, free T4 (older adults only):

        normal

      Vasovagal syncope

      History

      previous history (including childhood) of faints; typical premonitory warning symptoms of feeling warm, nauseated, dizzy, distant from surroundings (may not be reported by older patients)

      Exam

      normal cardiac examination; features of witnessed event include transient loss of consciousness, may be myoclonic type jerks during the event, may appear flushed initially with pallor immediately preceding loss of consciousness

      1st investigation
      • clinical exam:

        diagnosis may be made on history and exam findings alone

        More
      • ECG:

        normal

      Other investigations
      • basic test panel (CBC, serum electrolytes, blood glucose, serum LFTs, coagulation profile):

        normal

      • serum thyroid-stimulating hormone, free T4 and serum vitamin B12 (older adults only):

        normal

      • tilt table testing with beat-to-beat (phasic) BP monitoring (e.g., digital artery photoplethysmography):

        reproduction of symptoms with prolonged (40 min) tilt

        More

      Medication-related

      History

      history of recently introduced medication known to produce hypotension; common responsible drug classes include beta-blockers, alpha-blockers, diuretics, nitrates, calcium channel blockers, ACE inhibitors, L-dopa, tricyclic antidepressants, phenothiazines, opioids (in high doses), intravenous acetaminophen in critically ill hospitalized patients; more common in older adults

      Exam

      change in BP readings date from after introduction of new medication, and improvement noted after discontinuation of drug; no specific physical exam findings to suggest other cause

      1st investigation
      • discontinuation of suspected precipitating medication:

        clinical improvement on discontinuation of medication

        More
      • urine toxicology screen:

        may be positive for opioids

      Other investigations
      • basic test panel (CBC, serum electrolytes, blood glucose, serum LFTs, coagulation profile):

        normal

      • serum thyroid-stimulating hormone and free T4 and serum vitamin B12 (older adults only):

        normal

      • ECG:

        normal

      Pregnancy (uncomplicated)

      History

      woman of childbearing age; delayed menstruation; history of unprotected sexual intercourse; may be known pregnancy or history may indicate the patient is unaware she is pregnant

      Exam

      gravid uterus on abdominal or pelvic exam; fetal heart on auscultation

      1st investigation
      • urinary pregnancy test:

        positive

      • serum beta HCG:

        positive

      Other investigations
      • pelvic ultrasound:

        live fetus present

      Sepsis

      History

      symptoms of localized infection, nonspecific symptoms include fever or shivering, dizziness, nausea and vomiting, muscle pain, feeling confused or disoriented; may be history of risk factors (e.g., immunosuppression, pregnancy or postpartum period, frailty, recent surgery or invasive procedures, intravenous drug use, or breach of skin integrity)

      Exam

      tachycardia, tachypnea, hypotension, fever >101°F (>38°C) or hypothermia >97°F (<36°C), prolonged capillary refill, mottled or ashen skin, cyanosis, low oxygen saturation, newly altered mental state, reduced urine output

      1st investigation
      • blood culture:

        may be positive for organism

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      • serum lactate:

        may be elevated; levels >18 mg/dL (>2 mmol/L) associated with adverse prognosis; even worse prognosis with levels ≥36 mg/dL (≥4 mmol/L) elevated

        More
      • CBC with differential:

        WBC count >12×10⁹/L (12,000/mL) (leukocytosis); WBC count <4×10⁹/L (4000/mL) (leukopenia); or a normal WBC count with >10% immature forms; low platelets

        More
      • C-reactive protein:

        elevated

      • blood urea and serum electrolytes:

        serum electrolytes may be deranged; blood urea may be elevated

      • serum creatinine:

        may be elevated

        More
      • LFTs:

        may show elevated bilirubin, alanine aminotransferase, aspartate aminotransferase, alkaline phosphatase, and gamma glutamyl transpeptidase

        More
      • coagulation studies:

        may be abnormal

      • ECG:

        may show evidence of ischemia, atrial fibrillation, or other arrhythmia; may be normal

        More
      • ABG:

        may be hypoxia, hypercapnia, elevated anion gap, metabolic acidosis

      Other investigations
      • urine microscopy and culture:

        may be positive for nitrites, protein or blood; elevated leukocyte count; positive culture for organism

      • sputum culture:

        may be positive for organism

      • chest x-ray:

        may show pleural effusion, consolidation, cardiac abnormalities or a pneumothorax, demonstrates position of central venous catheter and tracheal tube

      • echocardiogram:

        inadequate left ventricular filling suggests hypovolemia; vegetations if endocarditis cause of sepsis

        More
      • lumbar puncture:

        may be elevated WBC count, presence of organism on microscopy and positive culture

        More

      Chronic liver disease

      History

      known history of chronic liver disease; pruritus; abdominal swelling; confusion; lethargy; weight loss; weakness; bruising; may be worsening light-headedness and unsteadiness in presence of concurrent hematemesis, melena or other symptoms of gastrointestinal bleed; history of sepsis (fever, anorexia, focal symptoms depending on site of infection)

      Exam

      may be jaundice; muscle wasting; gynecomastia; palmar erythema; spider angiomata; petechiae; ascites; distended abdominal veins; hepatosplenomegaly; signs of encephalopathy (e.g., memory, attention, and concentration deficits, confusion, asterixis, nystagmus, clonus, rigidity, coma)

      1st investigation
      • basic test panel (CBC, serum electrolytes, blood glucose, serum LFTs, coagulation profile):

        elevated liver enzymes; elevated bilirubin (conjugated); may be low Hb and low platelets; INR may be elevated

      • serum thyroid-stimulating hormone, free T4 (older adults only):

        normal

      • ECG:

        normal

      Other investigations
      • blood cultures:

        concurrent sepsis: infective organism isolated

      • urine microscopy and culture:

        concurrent urinary infection: infective organism isolated

      • paracentesis:

        concurrent infective peritonitis: infective organism isolated

        More
      • upper gastrointestinal endoscopy:

        may demonstrate source of gastrointestinal bleed, varices may be visualized

      Parkinson disease

      History

      more common in older adults; usually long-standing history of Parkinson disease; may be recent initiation or change in anti-Parkinsonian medication, or symptoms of concurrent general medical illness (e.g., dysuria and urinary frequency with urosepsis, or cough with purulent sputum with pneumonia)

      Exam

      bradykinesia; tremor; increased tone; postural instability; stooped shuffling gait with reduced arm-swing, mask-like face; signs of intercurrent infection (e.g., fever, crackles on chest auscultation)

      1st investigation
      • basic test panel (CBC, serum electrolytes, blood glucose, serum LFTs, coagulation profile):

        CBC may show elevated WBC count if infection present

      • serum thyroid-stimulating hormone, free T4 and serum B12 (older adults only):

        normal

      • ECG:

        normal

      Other investigations

        Uncommon

        Ruptured abdominal aortic aneurysm

        History

        abdominal pain radiating to back; abdominal distension; bilateral flank pain; light-headedness; may be a history of risk factors (e.g., smoking, peripheral vascular disease, known history of aneurysm)

        Exam

        hypotension may be profound with decreasing level of consciousness; abdominal tenderness; pulsatile mass; weak peripheral pulses

        1st investigation
        • clinical exam:

          diagnosis of acute rupture is usually made by history and clinical findings

          More
        Other investigations
        • bedside abdominal ultrasound:

          may demonstrate site of leak or extravasation; color flow Doppler can aid detection; sensitivity and specificity for rupture are low

          More
        • CT thorax and abdomen:

          impending rupture: may demonstrate blood within the thrombus (crescent sign), low thrombus-to-lumen ratio, retroperitoneal hematoma, discontinuity of the aortic wall, or extravasation of contrast into the peritoneal cavity

          More

        Ectopic pregnancy

        History

        women of childbearing age; amenorrhea; may be known pregnancy; abdominal pain; vaginal bleeding; may be history of previous ectopic pregnancy, prior tubal surgery, pelvic inflammatory disease, or intrauterine contraception use

        Exam

        tachycardia; abdominal tenderness and guarding; decreased bowel sounds; cervical motion tenderness; vaginal bleeding

        1st investigation
        • urinary pregnancy test:

          positive

          More
        • CBC, type and cross:

          may be low Hb

          More
        Other investigations
        • transvaginal ultrasound:

          visualization of ectopic pregnancy; empty uterus

        Retroperitoneal bleed

        History

        symptoms may be vague; groin, lower abdominal, or back pain; history of risk factors (e.g., recent anticoagulation use, recent history of cardiac or femoral angiography, recent obstetric procedure in women of childbearing age)

        Exam

        unexplained tachycardia; tenderness in lower abdomen on side of bleed; may be bruising of flank; diaphoresis if severe; profound hypotension with decreasing levels of consciousness if shock present

        1st investigation
        • basic test panel (CBC, serum electrolytes, blood glucose, serum LFTs coagulation profile, type and cross):

          low Hb; INR may be elevated

        • ECG:

          normal, or tachycardia

        Other investigations
        • CT abdomen:

          hematoma may be visualized

        • CT angiogram:

          may demonstrate active bleeding site if bleeding is ongoing

        Severe acute pancreatitis

        History

        Sudden-onset continuous upper abdominal pain, typically radiating to the back; nausea and vomiting, malaise; history of alcohol use or gallstones, may be history of azathioprine, mercaptopurine or didanosine use

        Exam

        Epigastric or left upper quadrant tenderness with voluntary guarding, abdominal distension, may be reduced bowel sounds; hypotension, dry mucous membranes, reduced skin turgor, oliguria, sweating, tachycardia, tachypnea; signs of pleural effusion (more commonly left side); jaundice

        1st investigation
        • serum lipase or amylase:

          >3 times the upper limit of normal

          More
        • basic test panel (CBC, serum electrolytes, serum calcium, blood glucose, serum LFTs):

          CBC: leukocytosis, elevated hematocrit indicates dehydration; elevated urea and/or creatinine in dehydration; elevated aminotransferases suggests gallstones as the cause; hypercalcemia is a rare cause of pancreatitis

        • C-reactive protein:

          elevated

        • arterial blood gas:

          may show hypoxemia or acid-base disturbance

        Other investigations
        • chest x-ray:

          may show atelectasis and pleural effusion

        • transabdominal ultrasound:

          may show gallstones; may show pancreatic inflammation, peripancreatic stranding, calcifications or fluid collections

          More

        Carotid sinus syndrome (cardioinhibitory subtype)

        History

        history of recurrent or unexplained falls, drop attacks or collapse episodes occurring in an older adult (usually >70 years); patient may not report classical precipitant of neck extension or turning

        Exam

        usually unremarkable clinical findings; on clinical exam there are no differentiating features from the vasodepressor subtype of carotid sinus syndrome and differential findings are almost always at time of tilt table testing with carotid sinus massage

        1st investigation
        • basic test panel (CBC, serum electrolytes, blood glucose, serum LFTs, serum troponin, d-dimer, coagulation profile):

          normal

        • serum thyroid-stimulating hormone, free T4 and serum vitamin B12 (older adults only):

          normal

        • ECG:

          usually normal; may show first degree heart block

        • tilt table test with carotid sinus massage:

          inducible cardiac pause/asystole exceeding 3 seconds

        Other investigations

          Severe hypothyroidism

          History

          weight gain; weakness; lethargy; slow speech; cold sensation; forgetfulness; constipation; neck swelling

          Exam

          evidence of severe hypothyroidism (e.g., coma, hypothermia, signs of heart failure); coarse hair; facial edema; bradycardia; eyelid edema; thick tongue

          1st investigation
          • basic test panel (CBC, serum electrolytes, blood glucose, serum LFTs, serum troponin, coagulation profile):

            CBC: may have elevated MCV

          • serum thyroid-stimulating hormone, free T4:

            primary hypothyroidism: elevated thyroid-stimulating hormone, low T4

          • serum B12 (older adults only):

            normal

          Other investigations

            Tension pneumothorax

            History

            sudden onset pleuritic chest pain; severe and worsening dyspnea; rapid deterioration; may be risk factors (e.g., recent placement of central venous pressure line, history of emphysema or chest trauma)

            Exam

            acute distress; cyanosis; profuse diaphoresis; tachycardia; absent unilateral breath sounds; hyperresonance to percussion on affected side; tracheal shift from midline; hypotension develops rapidly with subsequent loss of consciousness

            1st investigation
            • diagnostic and therapeutic needle thoracostomy:

              hiss of air as catheter/needle enters the pleural space

              More
            Other investigations
            • post-decompression chest x-ray:

              shows a visceral pleural line; confirms position of intercostal drain

              More

            Cardiac tamponade

            History

            chest pain reduced by sitting forward; shortness of breath; may be risk factors present (e.g., recent myocardial infarction, pericarditis, coronary angiogram, or cardiac surgery)

            Exam

            hypotension may be profound with decreasing level of consciousness; increased respiratory rate; distended jugular veins, reduced heart sounds and hypotension (Beck triad); tachycardia; pulsus paradoxus (high positive predictive value and sensitivity, though lower specificity)

            1st investigation
            • chest x-ray:

              enlargement of cardiac shadow

            • ECG:

              rhythm strip: beat-to-beat electrical alternans

            • echocardiogram:

              typically: large pericardial effusion (>20 mm of echo-free space in diastole between the visceral and parietal pericardium); chamber collapse and respiratory variation of ventricular filling

              More
            Other investigations
            • basic test panel (CBC, serum electrolytes, blood glucose, serum LFTs, serum troponin, d-dimer, coagulation profile):

              may be low Hb if anemia is a related cause; viral pericarditis: elevated WBC count; elevated troponin if cardiac trauma or myocardial infarction

            • erythrocyte sedimentation rate:

              elevated in the presence of inflammatory or infective cause

            Situational syncope

            History

            previous history of faints precipitated by similar event, recognized precipitants include micturition, defecation, exercise, brass instrument playing, weightlifting, and eye exam

            Exam

            normal cardiac exam; features of witnessed event include transient loss of consciousness, may be myoclonic type jerks during the event, pallor

            1st investigation
            • clinical exam:

              diagnosis may be made on history and exam findings alone

              More
            • ECG:

              normal

            Other investigations
            • basic test panel (CBC, serum electrolytes, blood glucose, serum LFTs, coagulation profile):

              normal

            • serum thyroid-stimulating hormone, free T4 and serum vitamin B12 (older adults only):

              normal

            Anaphylaxis

            History

            history of recent ingestion/exposure to known allergen (e.g., bee sting); acute onset of symptoms with rapid deterioration; wheeze; rash; swollen lips or tongue; swollen eyelids; pruritus; agitation; anxiety; impending sense of doom (angor animi); nausea; vomiting; diarrhea; light-headedness

            Exam

            rapidly progressive signs; signs of bronchospasm (e.g., audible wheeze, use of accessory muscles); erythematous confluent rash or itchy urticarial wheals; angioedema of tongue, lips or eyelids; flushing; rhinitis; inspiratory stridor; syncope; delirium; coma

            1st investigation
            • clinical exam:

              diagnosis usually made clinically with treatment started without delay for testing

              More
            Other investigations
            • mast cell tryptase:

              may be elevated; can range from insignificantly elevated to levels above 100 nanograms/mL

              More
            • post-episode CBC:

              eosinophilia

            • post-episode serum histamine:

              >1.1 micrograms/L

            • post-episode radioallergosorbent test:

              >0.35 international units/L

            • post-episode specific skin tests (Ig E):

              >3mm diameter and greater than control

            • post-episode challenge test:

              objective symptoms of allergy response

            • post-episode urine test for N-methyl histamine:

              increased compared with baseline

            Carotid sinus syndrome (vasodepressor subtype)

            History

            history of recurrent or unexplained falls, drop attacks or collapse episodes occurring in an older adult (usually >70 years); patient may not report classical precipitant of neck extension or turning

            Exam

            usually unremarkable clinical findings; typically there are no definite differentiating features on clinical exam from the cardio-inhibitory subtype of carotid sinus syndrome and tilt table test with carotid sinus massage is required

            1st investigation
            • basic test panel (CBC, serum electrolytes, blood glucose, serum LFTs, serum troponin, d-dimer, coagulation profile):

              normal

            • serum thyroid-stimulating hormone, free T4 and serum vitamin B12 (older adults only):

              normal

            • ECG:

              normal

            • tilt table test with carotid sinus massage:

              symptomatic fall in BP ± syncope precipitated. Pure vasodepressor subtype does not have an associated cardiac pause

              More
            Other investigations

              Diabetic autonomic neuropathy

              History

              known history of diabetes mellitus; may be known peripheral neuropathy; loss of sensation in feet and hands; painless injuries; dysesthesia

              Exam

              impaired peripheral (glove and stocking distribution) sensation; evidence of painless injuries particularly of feet; absent ankle reflexes; orthostatic hypotension

              1st investigation
              • basic test panel (CBC, serum electrolytes, blood glucose, serum LFTs, coagulation profile):

                random blood glucose: may be normal if diabetes is well controlled, or elevated if poorly controlled/new diagnosis

                More
              • serum thyroid-stimulating hormone, free T4 and serum vitamin B12 (older adults only):

                normal

              • ECG:

                may be normal; comorbid coronary disease: may demonstrate ischemic changes

              • fasting blood glucose:

                new diagnosis of diabetes: 126 mg/dL or higher

                More
              • HbA1c:

                variable depending on degree of glucose control

                More
              Other investigations
              • nerve conduction studies:

                reduction in sensory nerve conduction velocity and a decrease in amplitude is the most sensitive and earliest result

                More

              Multi-system atrophy

              History

              more commonly older adult; parkinsonism symptoms recently noted; may be history of falls or unexplained injuries

              Exam

              bradykinesia; tremor; increased tone; upward gaze palsy; commonly orthostatic hypotension detected; parkinsonism, cerebellar, autonomic and urological dysfunction in any combination

              1st investigation
              • basic test panel (CBC, serum electrolytes, blood glucose, serum LFTs, coagulation profile):

                CBC may show elevated WBC count if infection present

              • serum thyroid-stimulating hormone, free T4 and serum vitamin B12 (older adults only):

                normal

              • ECG:

                normal

              Other investigations

                Post-stroke

                History

                recent stroke, typically in preceding days; most commonly right cerebral hemisphere stroke; reduction in patient's level of consciousness or deterioration in his/her mobility and ability to sit upright over time; history of recent introduction of BP lowering medication

                Exam

                signs of stroke (neurological deficit dependent on cerebral region affected); BP measurements may appear normal at first glance but have shown a drop since initial admission (hypertensive) BP readings

                1st investigation
                • basic test panel (CBC, serum electrolytes, blood glucose, serum LFTs, serum troponin, d-dimer, coagulation profile):

                  normal

                • serum thyroid-stimulating hormone, free T4 and serum vitamin B12 (older adults only):

                  normal

                  More
                Other investigations
                • ECG:

                  normal or ischemic changes

                • fasting serum lipids ( total cholesterol, LDL cholesterol, HDL cholesterol and triglycerides):

                  variable

                Primary autonomic failure

                History

                may be a known history of autonomic failure and orthostatic hypotension; dizziness on standing; may be erectile dysfunction, constipation, decreased sweating; history of regular (daily) symptoms occurring within a short period (minutes) after posture change

                Exam

                no specific physical findings other than orthostatic hypotension; posture test positive (systolic BP falls >20 mmHg and diastolic BP falls >10 mmHg within 3 minutes orthostatic stress with lack of an adequate compensatory heart rate increase [>20 bpm]); if posture test normal should not deter from further investigation in the presence of suggestive history

                1st investigation
                • basic test panel (CBC, serum electrolytes, blood glucose, serum LFTs, coagulation profile):

                  normal

                • serum thyroid-stimulating hormone, free T4 and serum vitamin B12 (older adults only):

                  normal

                • ECG:

                  normal

                Other investigations
                • tilt table test with beat to beat BP monitoring (e.g., digital artery photoplethysmography):

                  profound and often prolonged hypotension in response to head up tilt often present; fall in systolic BP of >20 mmHg or diastolic BP >10 mmHg; supine hypertension may also be present; presence of presyncopal symptoms associated with hemodynamic changes

                • specialized physiological tests (plasma norepinephrine; deep breathing: Valsalva maneuver test; electrophysiological tests; quantitative sudomotor axon reflex test [QSART]: heart rate variability test):

                  failure to release norepinephrine on standing; diminished beat-to-beat variation on ECG during inspiration and expiration; failure of the BP overshoot after release of the strain during Valsalva maneuver; reduction in sensory nerve conduction velocity and muscle denervation on electrophysiological tests; absence of sweat production on QSART; decreased heart rate variability

                Amyloidosis

                History

                history of unexplained weight loss; parasthesia; shortness of breath; fatigue; dizziness on standing; may be a known history of amyloidosis, or of a chronic inflammatory condition known to predispose to amyloidosis development (e.g., rheumatoid arthritis)

                Exam

                macroglossia (specific for amyloidosis); periorbital purpura; lower limb edema which is resistant to diuretic therapy; elevated jugular venous pressure; orthostatic hypotension; signs of a chronic inflammatory condition (e.g., rheumatoid deformities of joints, erythematous, tender joints, rheumatoid nodules, skin lesions)

                1st investigation
                • serum and urine immunofixation:

                  clonal plasma cells demonstrated

                • immunoglobulin free light chain assay:

                  abnormal kappa to lambda ratio

                • basic test panel (CBC, serum electrolytes, blood glucose, serum LFTs, coagulation profile):

                  associated renal insufficiency or gastrointestinal bleed: may be low Hb; hepatic amyloid: elevated alk phos

                • serum thyroid-stimulating hormone, free T4 and serum vitamin B12 (older adults only):

                  normal

                • ECG:

                  may demonstrate conduction abnormalities

                Other investigations
                • tissue biopsy:

                  positive (green) birefringence with Congo Red stain

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                Adrenal suppression (iatrogenic)

                History

                More common in patients with chronic inflammatory disorders such as rheumatoid arthritis, polymyalgia rheumatica, or inflammatory bowel disease. May be associated with intercurrent illness or abrupt withdrawal of chronic steroids

                Exam

                Hypotension may be mild; lethargy and decreased level of consciousness; stigmata indicative of underlying chronic inflammatory disorder such as rheumatoid hands; cushingoid appearance

                1st investigation
                • basic test panel (CBC, serum electrolytes, blood glucose, serum LFTs, coagulation profile):

                  serum electrolytes: may be hyponatremia and hyperkalemia, serum BUN may be elevated; CBC: WBC count may be elevated with intercurrent illness

                • serum thyroid-stimulating hormone, free T4 and serum vitamin B12 (older adults only):

                  normal

                  More
                • ECG:

                  normal

                • morning serum cortisol:

                  <3 micrograms/dL

                Other investigations
                • adrenocorticotrophic hormone stimulation test:

                  low serum cortisol pre-administration of cosyntropin with failure to rise after administration (<18 micrograms/dL)

                Addison disease

                History

                weight loss; anorexia; increased pigmentation; fatigue; nausea and vomiting; salt craving; dizziness

                Exam

                hyperpigmentation (commonly mucous membranes and sun-exposed areas, more pronounced in palmar creases, areas of friction, and scars)

                1st investigation
                • basic test panel (CBC, serum electrolytes, blood glucose, serum LFTs, coagulation profile):

                  serum electrolytes: may be hyponatremia and hyperkalemia, serum BUN may be elevated; CBC: may be low Hb, eosinophilia

                • serum thyroid-stimulating hormone, free T4 and serum vitamin B12 (older adults only):

                  normal

                  More
                • ECG:

                  normal

                • morning serum cortisol:

                  <3 micrograms/dL

                  More
                Other investigations
                • adrenocorticotropic hormone stimulation test:

                  low serum cortisol pre-administration of cosyntropin with failure to rise after administration (<18 micrograms/dL)

                Hypopituitarism

                History

                failure to thrive in childhood; short stature; failure of secondary characteristics; oligomenorrhea; infertility; headache; visual field defects; blurred vision

                Exam

                dry skin; breast atrophy; increased body mass index; loss of axillary and pubic hair; ophthalmoplegia

                1st investigation
                • basic test panel (CBC, serum electrolytes, blood glucose, serum LFTs, coagulation profile):

                  low serum sodium

                • serum thyroid-stimulating hormone, free T4:

                  low free T4, low or normal thyroid-stimulating hormone

                • morning serum cortisol:

                  <3 micrograms/dL

                • morning serum testosterone, LH, FSH (in men):

                  all low

                • morning serum estradiol, LH, FSH (in women):

                  all low

                • serum prolactin:

                  may be elevated

                Other investigations
                • adrenocorticotrophic hormone stimulation test:

                  low serum cortisol pre-administration of cosyntropin with failure to rise after administration (<18 micrograms/dL)

                • serum insulin like growth factor:

                  low

                Thiamine deficiency

                History

                presence of suggestive risk factors (e.g., alcohol abuse, recurrent vomiting, chronic diarrhea, postgastrointestinal surgery, AIDS, total parenteral nutrition, diet of polished rice); fatigue; weakness; muscle aches; reduced peripheral sensation; swollen legs; poor balance; confusion; paresthesia

                Exam

                peripheral edema; reduced knee jerks and other tendon reflexes; severe muscle weakness; muscle wasting; tachycardia; signs of Wernicke encephalopathy (e.g., mental state changes such as acute confusion, ataxia, and ocular abnormalities such as nystagmus and strabismus)

                1st investigation
                • trial of thiamine replacement therapy:

                  clinical improvement may support diagnosis

                • erythrocyte thiamine pyrophosphate level:

                  reduced

                  More
                • basic test panel (CBC, serum electrolytes, blood glucose, serum LFTs, coagulation profile):

                  CBC: macrocytosis

                • serum thyroid-stimulating hormone, free T4:

                  normal

                  More
                • serum B12 (older adults only):

                  normal

                • ECG:

                  normal

                Other investigations
                • ABG:

                  elevated anion gap, metabolic acidosis

                • serum lactate:

                  elevated

                • MRI brain:

                  Wernicke encephalopathy: bilateral increased T2 signal in the paraventricular regions of the thalamus, hypothalamus, mammillary bodies, periaqueductal region, fourth ventricle floor, and midline cerebellum

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                Vitamin B12 deficiency

                History

                may be known vitamin B12 deficiency; may be risk factors present (e.g., elderly people, patients with chronic malabsorption, history of gastric resection or bypass, and those taking certain medications such as metformin, proton pump inhibitors); lower limb numbness; other parasthesia; depressed mood

                Exam

                decreased vibration sense; gait abnormalities; decreased peripheral sensation; absent ankle jerks; signs of depression or dementia; exam may be normal; late signs: angular cheilitis, glossitis, pallor and bruising

                1st investigation
                • basic test panel (CBC, serum electrolytes, blood glucose, serum LFTs, coagulation profile):

                  CBC: may be normal but may be low Hb, elevated MCV, low hematocrit; peripheral blood smear: megalocytes, hypersegmented polymorphonucleated cells

                • serum vitamin B12:

                  <200 picograms/mL is highly suggestive of deficiency

                  More
                • serum thyroid-stimulating hormone, free T4 (older adults only):

                  normal

                  More
                • ECG:

                  normal

                • reticulocyte count:

                  low corrected reticulocyte index

                Other investigations

                  Carcinoid syndrome

                  History

                  associated symptoms of flushing, diarrhea, abdominal pain, palpitations and wheeze

                  Exam

                  peripheral edema secondary to right heart failure, tachycardia, telangiectasia, cardiac murmur, hepatomegaly, wheeze, abdominal mass

                  1st investigation
                  • 24 hours of urinary excretion of 5-hydroxyindole acetic acid:

                    elevated

                    More
                  • CT scan chest, abdomen and pelvis:

                    identifies location of primary tumor and presence of liver metastases

                  Other investigations

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