Differentials

Diabetic ketoacidosis (DKA)

SIGNS / SYMPTOMS
INVESTIGATIONS
SIGNS / SYMPTOMS

Patients are often younger and usually have type 1 diabetes.

Abdominal pain is uncommon in HHS but frequently seen (>50%) in patients in DKA.[1]​​

In the US, patients with ketosis-prone type 2 diabetes are almost exclusively African-American or Hispanic in origin.[61]

INVESTIGATIONS

Venous pH <7.3.

Bicarbonate <15 mmol/L (<15 mEq/L).[62] 

Ketonaemia (ketones >3.0 mmol/L) or ketonuria (more than 2+ or more on standard urine sticks).[62]

Diabetic ketoacidosis

Lactic acidosis

SIGNS / SYMPTOMS
INVESTIGATIONS
SIGNS / SYMPTOMS

May be clinically indistinguishable from HHS and DKA, although most patients do not have a history of diabetes.

Sometimes occurs in association with HHS and DKA.

INVESTIGATIONS

Venous pH <7.3.

Bicarbonate <15 mmol/L (<15 mEq/L); anion gap >12 mmol/L (>12 mEq/L).

Lactic acid >5 mmol/L.

Serum glucose and ketones are normal.

Assessment of metabolic acidosis

Alcohol ketoacidosis

SIGNS / SYMPTOMS
INVESTIGATIONS
SIGNS / SYMPTOMS

A history of chronic alcohol abuse is present.

Produced by starvation due to poor food intake.

Peripheral signs of chronic liver disease, such as spider naevi, leukonychia, palmar erythema, bruising, jaundice, scratch marks, and hepatomegaly, are present.

INVESTIGATIONS

Venous pH is variable and can be normal.

Bicarbonate <15 mmol/L (<15 mEq/L); anion gap >12 mmol/L (>12 mEq/L).

Serum glucose is low or normal but serum ketones or beta-hydroxybutyrate is elevated.

Lactate levels are usually elevated but elevation is insufficient to account for acidosis.

Alcohol-use disorder

Ingestion of toxic substances

SIGNS / SYMPTOMS
INVESTIGATIONS
SIGNS / SYMPTOMS

History of ingestion of ethanol, methanol, ethylene glycol (constituent of automobile antifreeze), and/or propylene glycol (diluent in many intravenous medications, such as lorazepam) is present.

Paraldehyde ingestion is suggested by its characteristic strong odour in the breath.[1]

INVESTIGATIONS

Serum methanol levels will be elevated.[1]

Calcium oxalate and hippurate crystals in the urine suggest ethylene glycol ingestion.[1]

These organic toxins can produce an osmolar gap in addition to an anion gap due to their low molecular weight.[1]

Seizures

SIGNS / SYMPTOMS
INVESTIGATIONS
SIGNS / SYMPTOMS

Patient may have a history of prior seizure events.

May present with widespread motor manifestations.

INVESTIGATIONS

Urea and electrolytes may be normal.

Electroencephalogram (EEG) will show epileptiform activity.

Overview of seizure disorder

Stroke

SIGNS / SYMPTOMS
INVESTIGATIONS
SIGNS / SYMPTOMS

In most cases, the symptoms of stroke appear rapidly, over seconds or minutes.

Patients may present with limb and/or facial weakness (typically affects face, leg, and arm equally); may show visual disturbance.

INVESTIGATIONS

Urea and electrolytes are normal.

Cranial CT demonstrates haemorrhage or attenuation (although in ischaemic stroke, initial CT scan can be normal or show very subtle changes of ischaemia).

Overview of stroke

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