Leg cramps

Introduction
Leg cramps are sudden, involuntary, and painful contractions of muscles in the leg, most often affecting the calf but sometimes the thigh or foot muscles. They usually last from a few seconds to several minutes and can occur during activity or at rest, particularly at night (nocturnal leg cramps). While they are generally benign, persistent or severe cramps may indicate underlying medical conditions or medication side effects.

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Causes

Physiological / Benign Causes

• Muscle fatigue from excessive exercise or prolonged standing.

• Dehydration or excessive sweating.

• Electrolyte imbalance (low magnesium, potassium, calcium).

• Pregnancy (especially in the third trimester).

• Idiopathic nocturnal leg cramps (most common in older adults).

Medical Conditions

• Peripheral artery disease (PAD).

• Peripheral neuropathy.

• Chronic venous insufficiency.

• Spinal nerve root compression (lumbar radiculopathy).

• Metabolic disorders (hypothyroidism, liver disease, diabetes).

• Kidney disease with secondary electrolyte disturbances.

Medication-Induced

• Diuretics (e.g., furosemide, hydrochlorothiazide).

• Statins (e.g., atorvastatin, simvastatin).

• Beta-agonists (e.g., salbutamol).

• Nifedipine and other calcium channel blockers.

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Clinical Presentation

• Sudden sharp pain in the affected muscle, lasting seconds to minutes.

• Palpable hardening of the muscle during the cramp.

• Residual muscle tenderness after resolution.

• No associated swelling or redness in benign cases.

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Diagnosis

Leg cramps are diagnosed clinically through history and physical examination. Laboratory and imaging studies are only needed if there is suspicion of an underlying disorder.
Possible investigations include:

• Serum electrolytes (potassium, calcium, magnesium).

• Renal function tests.

• Thyroid function tests.

• Doppler ultrasound (for vascular causes).

• Nerve conduction studies (if neuropathy suspected).

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Management

Non-Pharmacological Measures

• Stretching exercises: Regular calf and hamstring stretches before bedtime.

• Hydration: Adequate daily fluid intake.

• Activity modification: Avoid prolonged standing or intense exercise without breaks.

• Massage and heat therapy: Gentle massage or warm compresses to relax muscles.

• Foot position in bed: Avoid pointing toes downward during sleep.

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Pharmacological Management
Medication is considered when cramps are frequent, severe, and not relieved by non-drug measures.

1. Magnesium supplementation

   • Magnesium citrate or magnesium oxide: 300–400 mg orally once daily (may be more effective in pregnancy-related cramps).

2. Calcium supplementation (if deficiency confirmed)

   • Calcium carbonate: 500–1000 mg elemental calcium daily in divided doses.

3. Potassium supplementation (only if hypokalemia confirmed)

   • Potassium chloride: Dose based on serum levels, typically 20–40 mEq orally daily.

4. Vitamin B complex

   • B-complex tablet once daily (may help in neuropathy-related cramps).

5. Quinine sulfate (last resort in selected cases)

   • 200–300 mg orally at night for severe, persistent idiopathic cramps unresponsive to other measures.

   • Not recommended in pregnancy or patients with cardiac arrhythmias; requires monitoring for side effects (tinnitus, thrombocytopenia, visual disturbances).

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Special Considerations

• In pregnancy, non-drug measures and magnesium supplementation are preferred.

• In elderly patients, avoid quinine unless benefits outweigh risks.

• Persistent cramps should prompt investigation for peripheral vascular disease, neuropathy, or metabolic disorders.

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Prognosis

Most leg cramps are benign and self-limiting. In cases related to reversible causes (e.g., dehydration, electrolyte imbalance), treatment of the underlying factor often results in full resolution. Chronic idiopathic nocturnal cramps may persist but can be managed with lifestyle changes and selective medication use.