What underlying conditions should I investigate in a patient presenting with frequent leg cramps?

Underlying conditions to investigate in a patient presenting with frequent leg cramps include:

• Electrolyte imbalances such as hypokalemia or other severe electrolyte disturbances.
• Volume depletion or dehydration.
• Acute kidney injury or other renal disorders.
• Neurological disorders, including lower motor neurone disease (MND).
• Primary muscle diseases.
• Systemic disorders that may present with altered consciousness, anuria, or abnormal body temperature.

Investigations may include serum creatine kinase (CK-MM) and aldolase for muscle disease, electromyography and nerve conduction studies for suspected neurological causes, muscle biopsy if indicated, and genetic studies if a familial cause is suspected. Referral to specialists such as neurology or rheumatology is recommended when an underlying cause is suspected that cannot be managed in primary care or if symptoms affect quality of life or diagnosis is uncertain.

Idiopathic leg cramps are common and often have no underlying cause; however, if cramps are severe, frequent, or associated with systemic symptoms, these underlying conditions should be considered and investigated appropriately.

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