Tests
1st tests to order
core temperature measurement
Test
Core temperature readings may be obtained with rectal or esophageal thermometers.[17]
Repeat readings are necessary to track temperature.
Result
>104°F (>40°C)
serum electrolytes
Test
Electrolyte abnormalities can result from volume depletion or overhydration with hypotonic fluids.
Presence of hypernatremia or hyponatremia will influence fluid management.[19]
Result
variable; dysnatremia
CBC
Test
Baseline CBC with differential should be obtained and followed up for 48 hours after a heat stroke event.
Result
variable; anemia and thrombocytopenia
LFTs
Test
Baseline LFTs should be obtained and followed up for 48 hours after a heat stroke event.
Result
variable; alanine aminotransferase and aspartate aminotransferase may be elevated
metabolic profile
Test
Baseline metabolic profile should be obtained and followed up for 48 hours after a heat stroke event.
Result
variable; may include elevated potassium, magnesium, and phosphate; low calcium
renal function tests
Test
Baseline renal function tests should be obtained and followed up for 48 hours after a heat stroke event.
Elevated sodium is an independent risk factor for death in nonexertional cases.[27]
Result
elevated creatinine and BUN
creatine kinase
Test
Baseline creatine kinase (CK) level should be obtained and followed up for 48 hours after a heat stroke event.
Specific test for diagnosis of rhabdomyolysis; CK levels have been shown to correlate with severity of rhabdomyolysis.
Result
variable; elevated CK (>1000 U/L) is common
prothrombin time, activated PPT, and INR
Test
Baseline coagulation profile should be obtained and followed up for 48 hours after a heat stroke event.
Elevations are associated with development of disseminated intravascular coagulation and indicate need for rapid management and increased levels of care.
Result
variable; may show elevated prothrombin time, activated PTT, and INR
lactic acid
urinalysis
Test
Myoglobin cross-reacts with blood assays on urine dipstick analysis.
Microscopy must be used to distinguish RBCs in urine from myoglobinuria.
Result
myoglobinuria and/or hemoglobinuria
chest x-ray
Test
Ordered as part of the initial workup of a patient with pyrexia and altered mental status to distinguish between heat stroke and pulmonary causes.
Pulmonary edema can also manifest as a later complication of heat stroke.
Result
variable; may show pulmonary edema
arterial blood gas
Test
Ordered if patients shows signs and symptoms of shock.
May indicate lactic acidosis and direct respiratory stimulation by the central nervous system.
Result
variable; metabolic acidosis and respiratory alkalosis
medication/toxicology screen
Test
Ordered if drug ingestion (e.g., cocaine, phencyclidines, salicylates) as a cause of pyrexia and central nervous system alterations is being considered.
Result
positive in the setting of medication/substance intoxication
thyroid function tests
Test
Ordered if hyperthyroidism is being considered as a diagnosis.
Result
normal
plasma glucose
Test
Ordered if diabetic ketoacidosis is being considered as a diagnosis.
Result
normal
Tests to consider
cranial CT scan
Test
Ordered if other causes of central nervous system alterations are being considered as a diagnosis.
Result
normal
lumbar puncture
Test
Ordered if meningitis as a cause of pyrexia and central nervous system alterations is being considered as a diagnosis.
Result
normal
blood culture
Test
Ordered if septicemia as a cause of pyrexia and central nervous system alterations is being considered as a diagnosis.
Result
negative
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