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Heatstroke: Differential Diagnoses & Workup

Author: Robert S Helman, MD, Director, Department of Emergency Medicine, Victory Memorial Hospital
Coauthor(s): Rania Habal, MD, Assistant Professor, Department of Emergency Medicine, New York Medical College
Contributor Information and Disclosures

Updated: Sep 18, 2009

Differential Diagnoses

Delirium
Meningitis
Delirium Tremens
Neuroleptic Malignant Syndrome
Diabetic Ketoacidosis
Tetanus
Encephalopathy, Hepatic
Toxicity, Cocaine
Encephalopathy, Uremic
Toxicity, Phencyclidine
Hyperthyroidism
Toxicity, Salicylate

Other Problems to Be Considered

Closed head trauma
Malignant hyperthermia
Encephalitis
Cerebral malaria
Cerebral hemorrhage
Amphetamine and cocaine toxicity
Strychnine poisoning

Workup

Laboratory Studies

  • Arterial blood gas analysis: ABG analysis may reveal respiratory alkalosis due to direct CNS stimulation and metabolic acidosis due to lactic acidosis. Hypoxia may be due to pulmonary atelectasis, aspiration pneumonitis, or pulmonary edema.
  • Lactic acidosis: Lactic acidosis commonly occurs following EHS but may signal a poor prognosis in patients with classic heatstroke.
  • Glucose: Hypoglycemia may occur in patients with EHS and in patients with fulminant hepatic failure.
  • Nutritional status and electrolytes
    • Sodium: Hypernatremia due to reduced fluid intake and dehydration commonly is observed early in the course of disease but may be due to diabetes insipidus. Hyponatremia is observed in patients using hypotonic solutions, such as free water, and in patients using diuretics. It also may be due to excessive sweat sodium losses.
    • Potassium: Hypokalemia is common in the early phases of heatstroke, and deficits of 500 mEq are not unusual. However, with increasing muscle damage, hyperkalemia may be observed.
    • Other: Hypophosphatemia secondary to phosphaturia and hyperphosphatemia secondary to rhabdomyolysis, hypocalcemia secondary to increased calcium binding in damaged muscle, and hypomagnesemia also are observed commonly.
  • Hepatic function tests
    • Hepatic injury is a consistent finding in patients with heatstroke.
    • Aminotransferases (aspartate aminotransferase [AST] and alanine aminotransferase [ALT]) commonly rise to the tens of thousands during the early phases of heatstroke and peak at 48 hours, but they may take as long as 2 weeks to peak.
    • Jaundice may be striking and may be noted 36-72 hours after the onset of liver failure.
  • Muscle function tests
    • Creatinine kinase (CK), lactate dehydrogenase (LDH), aldolase, and myoglobin commonly are released from muscles when muscle necrosis occurs.
    • CK levels exceeding 100,000 IU/mL are common in patients with EHS.
    • Elevations in myoglobin may not be noted despite muscle necrosis because myoglobin is metabolized rapidly by the liver and excreted rapidly by the kidneys.
  • Complete blood cell count: Elevated white blood cell counts commonly are observed in patients with heatstroke, and levels as high as 40,000 have been reported. Platelet levels may be low.
  • Renal function tests: Elevations in serum uric acid levels, blood urea nitrogen, and serum creatinine are common in patients whose course is complicated by renal failure.
  • Urinalysis: Remember that urinary benzidine dipsticks do not differentiate between blood, hemoglobin, and myoglobin. Urine dipstick analyses that are positive for blood must be followed by a microscopic urinalysis to determine the presence or absence of red blood cells. Proteinuria also is common.
  • Cerebrospinal fluid analysis: Cerebrospinal fluid (CSF) cell counts may show a nonspecific pleocytosis, and CSF protein levels may be elevated as high as 150 mg/dL.
  • Myoglobin causes a reddish brown discoloration of the urine but does not affect the color of plasma. This is in contrast to hemoglobin, which causes discoloration of both plasma and urine.

Imaging Studies

  • Computerized tomography scans may be helpful in ruling out CNS injury in patients with altered mental status.
  • Chest radiographs may show atelectasis, pneumonia, pulmonary infarction, or pulmonary edema.

Other Tests

  • Electrocardiography: Sinus tachycardia of 130-140 beats per minute and nonspecific and ischemic ST-T wave abnormalities are common. In addition, a number of conduction abnormalities (eg, right bundle branch block) and other conduction abnormalities (eg, prolonged QT interval) may be noted.

Procedures

  • Endotracheal intubation
  • Pulmonary artery catheter insertion
  • Central venous line insertion
  • Nasogastric tube insertion
  • Lumbar puncture
  • Compartment pressure measurements
  • Fasciotomy
  • Thoracostomy
  • Peritoneal lavage
  • Hemodialysis

More on Heatstroke

Overview: Heatstroke
Differential Diagnoses & Workup: Heatstroke
Treatment & Medication: Heatstroke
Follow-up: Heatstroke
References
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References

  1. Centers for Disease Control and Prevention. Heat Waves. Available at http://www.cdc.gov/climatechange/effects/heat.htm. Accessed July 2009.

  2. Centers for Disease Control and Prevention. Extreme Heat: A Prevention Guide to Promote Your Personal Health and Safety. Updated July 31, 2009. Available at http://emergency.cdc.gov/disasters/extremeheat/heat_guide.asp.

  3. Bouchama A, Dehbi M, Chaves-Carballo E. Cooling and hemodynamic management in heatstroke: practical recommendations. Critical Care 2007 [serial online]. 05/12/07;11 (issue 3):1-17. Accessed 02/03/07. Available at http://ccforum.com/content/11/3/R54.

  4. Ash CJ, Cook JR, McMurry TA, Auner CR. The use of rectal temperature to monitor heat stroke. Mo Med. May 1992;89(5):283-8. [Medline].

  5. Akhtar MJ, al-Nozha M, al-Harthi S, Nouh MS. Electrocardiographic abnormalities in patients with heat stroke. Chest. Aug 1993;104(2):411-4. [Medline].

  6. Armstrong LE, De Luca JP, Hubbard RW. Time course of recovery and heat acclimation ability of prior exertional heatstroke patients. Med Sci Sports Exerc. Feb 1990;22(1):36-48. [Medline].

  7. Bouchama A, Cafege A, Devol EB, Labdi O, el-Assil K, Seraj M. Ineffectiveness of dantrolene sodium in the treatment of heatstroke. Crit Care Med. Feb 1991;19(2):176-80. [Medline].

  8. Bouchama A, Hammami MM, Haq A, Jackson J, al-Sedairy S. Evidence for endothelial cell activation/injury in heatstroke. Crit Care Med. Jul 1996;24(7):1173-8. [Medline].

  9. Bouchama A, Knochel JP. Heat stroke. N Engl J Med. Jun 20 2002;346(25):1978-88. [Medline].

  10. Chou YT, Lai ST, Lee CC, Lin MT. Hypothermia attenuates circulatory shock and cerebral ischemia in experimental heatstroke. Shock. Apr 2003;19(4):388-93. [Medline].

  11. Costrini A. Emergency treatment of exertional heatstroke and comparison of whole body cooling techniques. Med Sci Sports Exerc. Feb 1990;22(1):15-8. [Medline].

  12. Dahmash NS, al Harthi SS, Akhtar J. Invasive evaluation of patients with heat stroke. Chest. Apr 1993;103(4):1210-4. [Medline].

  13. Easterling DR, Meehl GA, Parmesan C, Changnon SA, Karl TR, Mearns LO. Climate extremes: observations, modeling, and impacts. Science. Sep 22 2000;289(5487):2068-74. [Medline].

  14. Eichner ER. Treatment of suspected heat illness. Int J Sports Med. Jun 1998;19 Suppl 2:S150-3. [Medline].

  15. el-Kassimi FA, Al-Mashhadani S, Abdullah AK, Akhtar J. Adult respiratory distress syndrome and disseminated intravascular coagulation complicating heat stroke. Chest. Oct 1986;90(4):571-4. [Medline].

  16. Epstein Y, Moran DS, Shapiro Y, Sohar E, Shemer J. Exertional heat stroke: a case series. Med Sci Sports Exerc. Feb 1999;31(2):224-8. [Medline].

  17. Fish PD, Bennett GC, Millard PH. Heatwave morbidity and mortality in old age. Age Ageing. Jul 1985;14(4):243-5. [Medline].

  18. Hassanein T, Razack A, Gavaler JS, Van Thiel DH. Heatstroke: its clinical and pathological presentation, with particular attention to the liver. Am J Gastroenterol. Oct 1992;87(10):1382-9. [Medline].

  19. Hubbard RW. The role of exercise in the etiology of exertional heatstroke. Med Sci Sports Exerc. Feb 1990;22(1):2-5. [Medline].

  20. Hubbard RW, Gaffin SL, Squire DL. Heat-related illnesses. In: Auerbach P, ed. Wilderness Medicine: Management of Wilderness and Environmental Emergencies. 3rd ed. St. Louis, Mo:. Mosby Year Book;1995:167-212.

  21. Hubbard RW, Matthew CB, Durkot MJ, Francesconi RP. Novel approaches to the pathophysiology of heatstroke: the energy depletion model. Ann Emerg Med. Sep 1987;16(9):1066-75. [Medline].

  22. Khogali M, Weiner JS. Heat stroke: report on 18 cases. Lancet. Aug 9 1980;2(8189):276-8. [Medline].

  23. Kilbourne EM, Choi K, Jones TS, Thacker SB. Risk factors for heatstroke. A case-control study. JAMA. Jun 25 1982;247(24):3332-6. [Medline].

  24. Kumar S. India's heat wave and rain result in massive death toll. Lancet. 1998;351, No. 9119.

  25. Lomax P, Schonbaum E. The effects of drugs on thermoregulation during exposure to hot environments. Prog Brain Res. 1998;115:193-204. [Medline].

  26. MMWR. Heat-related illnesses, deaths, and risk factors--Cincinnati and Dayton, Ohio, 1999, and United States, 1979-1997. MMWR Morb Mortal Wkly Rep. Jun 2 2000;49(21):470-3. [Medline].

  27. Raju SF, Robinson GH, Bower JD. The pathogenesis of acute renal failure in heat stroke. South Med J. Mar 1973;66(3):330-3. [Medline].

  28. Shapiro Y, Seidman DS. Field and clinical observations of exertional heat stroke patients. Med Sci Sports Exerc. Feb 1990;22(1):6-14. [Medline].

  29. Shibolet S, Lancaster MC, Danon Y. Heat stroke: a review. Aviat Space Environ Med. Mar 1976;47(3):280-301. [Medline].

  30. Squire DL. Heat illness. Fluid and electrolyte issues for pediatric and adolescent athletes. Pediatr Clin North Am. Oct 1990;37(5):1085-109. [Medline].

  31. Tek D, Olshaker JS. Heat illness. Emerg Med Clin North Am. May 1992;10(2):299-310. [Medline].

  32. Tucker LE, Stanford J, Graves B, et al. Classical heatstroke: clinical and laboratory assessment. South Med J. Jan 1985;78(1):20-5. [Medline].

  33. Vassalo SU, Delaney KA. Thermoregulatory principles. In: Goldfrank's Toxicologic Emergencies. Stamford, Conn:. Appleton & Lange;1998:285-307.

  34. Vicario SJ, Okabajue R, Haltom T. Rapid cooling in classic heatstroke: effect on mortality rates. Am J Emerg Med. Sep 1986;4(5):394-8. [Medline].

  35. White JD, Riccobene E, Nucci R, et al. Evaporation versus iced gastric lavage treatment of heatstroke: comparative efficacy in a canine model. Crit Care Med. Aug 1987;15(8):748-50. [Medline].

  36. Yang YL, Lin MT. Heat shock protein expression protects against cerebral ischemia and monoamine overload in rat heatstroke. Am J Physiol. 1999;276:H1961-H1967.

  37. Yaqub B, Al Deeb S. Heat strokes: etiopathogenesis, neurological characteristics, treatment and outcome. J Neurol Sci. Apr 1 1998;156(2):144-51. [Medline].

  38. Yaqub BA, Al-Harthi SS, Al-Orainey IO, Laajam MA, Obeid MT. Heat stroke at the Mekkah pilgrimage: clinical characteristics and course of 30 patients. Q J Med. May 1986;59(229):523-30. [Medline].

  39. Yarbrough B, Bradham A. Heat illness. In: Emergency Medicine: Concepts and Clinical Practice. 1998. 4th ed. St Louis, Mo: Mosby Year Book; 1998:986-1002.

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Further Reading

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Keywords

heatstroke, heat stroke, hyperthermia, heat-related diseases, exertional heatstroke, EHS, heat exhaustion, heat illness, heat rash, heat edema, heat cramps, nonexertional heatstroke, hyperthermia

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Contributor Information and Disclosures

Author

Robert S Helman, MD, Director, Department of Emergency Medicine, Victory Memorial Hospital
Disclosure: Nothing to disclose.

Coauthor(s)

Rania Habal, MD, Assistant Professor, Department of Emergency Medicine, New York Medical College
Disclosure: Nothing to disclose.

Medical Editor

Laurie Robin Grier, MD, Medical Director of MICU, Associate Professor of Medicine, Section of Pulmonary and Critical Care Medicine, Louisiana State University Health Science Center at Shreveport
Laurie Robin Grier, MD is a member of the following medical societies: American College of Chest Physicians, American College of Physicians, American Society for Parenteral and Enteral Nutrition, and Society of Critical Care Medicine
Disclosure: Nothing to disclose.

Pharmacy Editor

Francisco Talavera, PharmD, PhD, Senior Pharmacy Editor, eMedicine
Disclosure: eMedicine Salary Employment

Managing Editor

Om Prakash Sharma, MD, FRCP, FCCP, DTM&H, Professor, Department of Medicine, Division of Pulmonary and Critical Care Medicine, University of Southern California Keck School of Medicine
Om Prakash Sharma, MD, FRCP, FCCP, DTM&H is a member of the following medical societies: American Academy of Allergy Asthma and Immunology, American College of Chest Physicians, American College of Physicians, American Federation for Medical Research, American Osler Society, American Thoracic Society, New York Academy of Medicine, and Royal Society of Medicine
Disclosure: Keck School of Medicine, USC None None

CME Editor

Timothy D Rice, MD, Associate Professor, Departments of Internal Medicine and Pediatrics and Adolescent Medicine, Saint Louis University School of Medicine
Timothy D Rice, MD is a member of the following medical societies: American Academy of Pediatrics and American College of Physicians
Disclosure: Nothing to disclose.

Chief Editor

Rick Kulkarni, MD, Assistant Professor of Surgery, Section of Emergency Medicine, Yale-New Haven Hospital
Rick Kulkarni, MD is a member of the following medical societies: Alpha Omega Alpha, American Academy of Emergency Medicine, American College of Emergency Physicians, American Medical Association, American Medical Informatics Association, Phi Beta Kappa, and Society for Academic Emergency Medicine
Disclosure: WebMD Salary Employment

 
 
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