Differentials
Diabetic ketoacidosis
SIGNS / SYMPTOMS
History of diabetes associated with suboptimal insulin therapy, sodium-glucose co-transporter 2 (SGLT-2) inhibitor therapy, or dehydration. May also be a first presentation of diabetes. 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 >13.9 mmol/L (>250 mg/dL) with presence of acidosis and ketonaemia. Serum glucose may be normal in patients taking SGLT-2 inhibitors.
Dementia
SIGNS / SYMPTOMS
More common among the older population. Positive family history of Alzheimer's dementia or personal history of cerebrovascular accident.
Cognitive decline is usually more gradual.
INVESTIGATIONS
Head CT or MRI scan shows hippocampal volume loss in cases of Alzheimer's, vascular, and Lewy body dementia; slowing of background rhythm on electroencephalogram is a common finding of Alzheimer's and Lewy body dementia.
Pneumonia
SIGNS / SYMPTOMS
Typically, fever is associated with cough, dyspnoea, sputum production, and chest pain.
INVESTIGATIONS
Chest x-ray may show defined infiltrates, consolidations, effusions, and/or cavitations.
Paracetamol overdose
SIGNS / SYMPTOMS
History of repeated non-prescription analgesic use for pain relief.
Acute paracetamol overdose produces few clinically useful findings on physical examination, particularly during the first 12 hours.
Poisoning may cause various degrees of liver injury, including fulminant hepatic failure and hepatorenal syndrome. Coma and severe metabolic acidosis are rare and are associated with late or delayed presentations of paracetamol overdose.
INVESTIGATIONS
Serum paracetamol concentration may be positive.
Alcohol poisoning (ethanol, ethylene glycol, methanol, or isopropyl alcohol)
SIGNS / SYMPTOMS
History of chronic alcohol consumption. Hepatomegaly or signs of chronic liver disease may be present (asterixis, spider nevi, leukonychia, palmar erythema, bruising, jaundice, scratch marks).
History of automobile anti-freeze or brake fluid ingestion in a confused patient with signs of metabolic acidosis (e.g., Kussmaul's respirations) suggests ethylene glycol poisoning.
Methanol toxicity is suggested by blindness or diminished visual acuity and optic neuritis on fundoscopic examination. In addition, seizures can occur and signs of metabolic acidosis may be present (e.g., Kussmaul's respirations).
Alteration in mental status, haematemesis, gait disturbances, dizziness, and confusion are common features of isopropyl alcohol ingestion. Hypothermia and hypotension may result from ingestion of large doses.[11]
INVESTIGATIONS
Serum toxicology screen (ethanol, methanol, ethylene glycol, isopropyl alcohol): positive; presence of osmolar gap, and an anion gap;[12] no metabolic acidosis with isopropyl alcohol; elevated serum lactate.
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 stroke-like episodes).
May have physical findings relating to the underlying cause.
INVESTIGATIONS
Wide anion-gap metabolic acidosis together with elevated serum lactate level confirms diagnosis.
Iron toxicity
SIGNS / SYMPTOMS
History of anaemia may be present (exposure to iron tablets and/or repeated blood transfusions pose risk of toxicity).
Gastrointestinal effects are common and include nausea, vomiting, diarrhoea, 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 species.
Alteration in mental state, coma, or cerebral oedema with concomitant abnormalities in hepatic function and liver enzymes.
INVESTIGATIONS
Elevated serum ammonia levels; elevated bilirubin; elevated prothrombin time; abnormal liver function tests.
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, dyspnoea, basal crackles, rales on chest auscultation, and pitting pedal oedema 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, myoglobin, or creatine kinase may be elevated.
Signs of pulmonary oedema may show on chest x-ray.
Signs of ischaemia 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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