Investigations
1st investigations to order
serum glucose
Test
Fingerstick glucose level done immediately at the bedside may exclude hypoglycaemia from differential.
Result
>3.3 mmol/L (60 mg/dL)
serum electrolytes
serum creatinine, urea
Test
Hyperthermia, hypovolaemia, or rhabdomyolysis may result in renal failure.
Result
creatinine >132.6 micromol/L (1.5 mg/dL); urea >7.1 mmol/L (20 mg/dL)
ABG
serum aspartate aminotransferase, alanine aminotransferase, gamma glutamyl transferase
Test
Reference normal range: aspartate aminotransferase (AST): 0.17-0.51 microkat/L (10-30 U/L), alanine aminotransferase (ALT): 0.17-0.68 microkat/L (10-40 U/L), gamma glutamyl transferase (gamma-GT): 0.03-0.51 microkat/L (2-30 U/L).
Hepatic failure occurs secondary to hepatocellular necrosis in hyperthermia.
Result
AST >0.5 microkat/L (30 U/L); ALT >0.7 microkat/L (40 U/L), gamma-GT >0.5 microkat/L (30 U/L)
serum prothrombin time, PTT, INR
Test
Diminished coagulation proteins are consistent with DIC associated with hyperthermia.
Result
normal or prolonged
urinalysis
Test
Intensely yellow or brown appearance and specific gravity >1.020 indicate concentrated urine, volume depletion.
Dipstick may cross-react positive for blood in rhabdomyolysis.
Result
dark yellow, specific gravity >1.020; dipstick normal or may be positive for blood
urine toxicology screen
Test
Amfetamines are usually detectable in urine for at least 48 hours.
Result
type of drug used, may indicate polydrug use
serum alcohol level
Test
Blood alcohol level may be lower in the presence of amfetamines.[64]
Result
variable
serum creatine kinase
Test
Rhabdomyolysis may occur as part of hyperthermia syndrome.
Result
normal or greatly elevated (e.g., peak >501 microkat/L [30,000 U/L])
serum troponin
Test
Warranted in patients with chest pain consistent with ischaemia.
May be detected 4 to 8 hours after myocardial infarction and persist for up to 10 days.
Result
normal or elevated
ECG
Test
Palpitations and tachycardia may require ECG for differentiation from arrhythmia.
Cardiac telemetry is recommended in patients with chest pain, tachycardia, or arrhythmias.
Result
tachycardia, may show arrhythmias, ischaemic changes
Chest x-ray
Test
Chest pain or dyspnoea warrants radiographs of the heart, lungs.
Pulmonary oedema may occur with cardiac failure.
Pneumothorax, pneumomediastinum may accompany trauma to the chest.
Result
may show pulmonary oedema, pneumothorax, pneumomediastinum
Investigations to consider
serum D-dimer
abdominal x-ray
Test
May occur in an attempt to conceal drug substances from authorities.
Result
rarely, may show ingested packages of drug
CT of the head
Test
Headache, altered states of consciousness, seizures, or neurological signs that are unexplained by serotonin toxicity may indicate intracranial pathology.
Result
rarely intracranial or subarachnoid haemorrhage, cerebral oedema
MRI of the head
Test
Headache, altered states of consciousness, seizures, or neurological signs that are unexplained by serotonin toxicity may indicate intracranial pathology. MRI is better than CT at identifying lesions at the grey-white interface.
Result
rarely intracranial or subarachnoid haemorrhage, cerebral oedema
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