Differentials
Diabetic ketoacidosis
SIGNS / SYMPTOMS
History of diabetes associated with suboptimal insulin therapy, sodium-glucose co-transporter 2 (SGLT-2) inhibitor therapy, or dehydration. Recent or current acute medical illness may be the precipitating factor.
Common symptoms include abdominal pain associated with polyuria, polyphagia, and polydipsia.
INVESTIGATIONS
Blood glucose >250 mg/dL with presence of acidosis and ketonemia. Serum glucose may be normal (e.g., in patients taking SGLT-2 inhibitors).
Dementia
SIGNS / SYMPTOMS
More common among the older population. May be family history of Alzheimer dementia or personal history of cerebrovascular accident.
Cognitive decline usually more gradual.
INVESTIGATIONS
Head CT or MRI scan shows hippocampal volume loss in cases of Alzheimer, vascular, and Lewy body dementia; slowing of background rhythm on EEG is common finding of Alzheimer and Lewy body dementia.
Pneumonia
SIGNS / SYMPTOMS
Typically, fever is associated with cough, dyspnea, sputum production, and chest pain.
INVESTIGATIONS
Chest x-ray may show defined infiltrates, consolidations, effusions, and/or cavitations.
Acetaminophen overdose
SIGNS / SYMPTOMS
History of repeated nonprescription analgesic use for pain relief may be present.
Acute acetaminophen overdose produces few clinically useful findings on physical exam, particularly during the first 12 hours.
Poisoning may cause various degrees of liver injury, including fulminant hepatic failure and hepatorenal syndrome. Initial coma and severe metabolic acidosis are rare, except in cases of massive acute overdose or late presentation.
INVESTIGATIONS
Serum acetaminophen concentration may be positive.
Alcohol poisoning (ethanol, ethylene glycol, methanol, or isopropyl alcohol)
SIGNS / SYMPTOMS
History of chronic alcohol consumption may suggest ethanol toxicity. Hepatomegaly or signs of chronic liver disease may be present (asterixis, spider nevi, leukonychia, palmar erythema, bruising, jaundice, scratch marks).
History of automobile antifreeze or brake fluid ingestion in a confused patient with signs of metabolic acidosis (e.g., Kussmaul respirations) suggests ethylene glycol poisoning.
Methanol toxicity is suggested by blindness or diminished visual acuity and optic neuritis on fundoscopic exam. In addition, seizures can occur and signs of metabolic acidosis may be present (e.g., Kussmaul respirations).
Alteration in mental status, hematemesis, gait disturbances, dizziness, and confusion are common features of isopropyl alcohol ingestion. Hypothermia and hypotension may result from ingestion of large doses.[19]
INVESTIGATIONS
Serum toxicology, anion gap, and acid-base status.
Serum ethanol concentrations are available at most hospitals. Serum ethylene glycol and methanol concentrations are less widely available. If these are not available, osmolar gap may be used to estimate ethylene glycol or methanol concentrations, though this method has limitations.
Anion gap metabolic acidosis is a major feature of ethylene glycol and methanol poisoning, and ethylene glycol poisoning causes acute kidney injury.[20] Measurement of serum isopropyl alcohol concentrations is not necessary. Anion gap and acid-base status are normal in isopropyl alcohol ingestion, though osmolar gap is increased.
Lactic acidosis
SIGNS / SYMPTOMS
History of possible underlying cause: tissue hypoperfusion, sepsis from various sources of infection, diabetes, medication (e.g., metformin), genetic defects (e.g., MELAS syndrome: mitochondrial encephalopathy, lactic acidosis, and strokelike episodes).
May have physical findings relating to underlying cause.
INVESTIGATIONS
Wide anion-gap metabolic acidosis together with elevated serum lactate level confirms diagnosis.
Iron toxicity
SIGNS / SYMPTOMS
History of anemia may be present (exposure to iron tablets and/or repeated blood transfusions pose risk of toxicity).
Gastrointestinal effects common and include nausea, vomiting, diarrhea, and abdominal pain.
INVESTIGATIONS
Elevated serum iron level.
Hepatic encephalopathy
SIGNS / SYMPTOMS
History of possible underlying cause: pre-existing liver disease or amatoxin poisoning after ingestion of Amanita spp.
Alteration in mental state, coma, or cerebral edema with concomitant abnormalities in hepatic function and liver enzymes.
INVESTIGATIONS
Elevated serum ammonia levels; elevated bilirubin; elevated prothrombin time; abnormal LFTs.
Cardiogenic shock
SIGNS / SYMPTOMS
History of coronary artery disease or congestive heart failure.
Chest pain, shortness of breath, lightheadedness, nausea.
Bradycardia or tachycardia, jugular vein distention, dyspnea, basal crackles, rales on chest auscultation, and pitting pedal edema are supportive of cardiac failure; a murmur may be heard on cardiac auscultation if a valve abnormality is present.
INVESTIGATIONS
Serum biomarkers such as troponins and B-type natriuretic peptide (BNP) may be elevated.
Signs of pulmonary edema may show on chest x-ray.
Signs of ischemia on ECG (ST-segment deviation, abnormal Q waves or loss of R wave, discordantly negative T waves or bundle branch block) and potentially critical arrhythmias, especially broad complex tachycardia .
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