II. Epidemiology

  1. Acclimatized athletes and laborers at end of work

III. Pathophysiology

  1. Hyponatremia and volume depletion from profuse sweating and replacement with hypotonic fluids
  2. Provoked by Muscle overload or Fatigue, Dehydration or Electrolyte disturbance

IV. Risk Factors

  1. See Heat Illness Risk Factors
  2. See Medications Predisposing to Heat Illness
  3. Athletes
  4. Field workers
  5. Roofers
  6. Steel Workers
  7. Coal Miners

V. Symptoms

  1. Symptom onset during or after exertion
  2. Brief, intermittent painful Muscle Contractions or cramps (esp. larger Muscle groups)
    1. Abdominal Muscles
    2. Gastrocnemius (Calves)
    3. Quadriceps
    4. Hamstrings
  3. Associated symptoms
    1. Increased thirst
    2. Excessive sweating
    3. Sinus Tachycardia

VI. Signs

  1. Distinguish from Heat Exhaustion
  2. Findings of Heat Stroke are absent
    1. Normal mentation and
    2. Core Temperature <104 F

VII. Labs

  1. Labs are not indicated in most cases of isolated Heat Cramps
    1. Consider lab testing if systemic symptoms suggest associated Heat Exhaustion
  2. Basic chemistry panel (chem8)
    1. Hyponatremia
    2. Hypochloremia
  3. Creatinine phosphokinase (CPK)

VIII. Management

  1. Rest
  2. Oral hydration with Electrolyte replacement (salt containing solution)
  3. Stretching and massage of cramping Muscles

IX. Prevention

  1. See Heat Illness Prevention
  2. Prior to work or Exercise:
    1. Adequate Stretching
    2. Adequate water intake
  3. With Exercise (especially longer than 1 hour)
    1. Ingest a drink containing Glucose and Sodium

X. References

  1. Czerkawski (1996) Your Patient Fitness 10(4): 13-20
  2. Salinas and Ruttan (2017) Crit Dec Emerg Med 31(9): 3-10
  3. Sandor (1997) Physician SportsMed, 25(6):35-40
  4. Zink (2020) Crit Dec Emerg Med 34(3): 19-27
  5. Barrow (1998) Am Fam Physician 58(3):749-56 [PubMed]
  6. Gauer (2019) Am Fam Physician 99(8):482-9 [PubMed]
  7. Hett (1998) Postgrad Med 103(6):107-20 [PubMed]
  8. Wexler (2002) Am Fam Physician 65(11):2307-20 [PubMed]

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