The exact cause of nocturnal leg cramps is unknown (idiopathic). However certain individuals with chronic conditions may be at risk of leg cramps at night. Nocturnal leg cramps are more common in older persons, especially women, and primarily affects the calf muscles and small muscles of the feet.
Leg cramps may occur as a symptom, side effect or complication to a multitude of secondary causes.
- Hormonal causes seen in pregnancy and menopause, hypoparathyroidism (the parathyroid hormone is responsible for calcium regulation), hypothyriodism or secondary hyopcalcemia seen in hyperthyriodism. Most possible hormonal causes of leg cramps may not be directly related to the process of nocturnal cramps but rather contribute to it indirectly due to calcium absorption and utilization.
- Drugs especially cholesterol lowering agents (statins) and diuretics which contributes to the loss of water and electrolytes. Certain diabetic drugs, anti-hypertensive medication, oral contraceptives and hormone replacement therapy may also contribute to leg cramps at night.
- Dehydration – loss of water and electrolytes (electrolyte imbalance) is known to contribute to muscle spasm.
- Overexertion and muscle fatigue.
- Changes of the gait (posture when standing and walking) and limping may strain muscles of the leg resulting in leg cramps.
- Inactivity and a lack of exercise could be a contributing factor to leg cramps.
- Calcium and/or magnesium deficiency which are two trace elements responsible for both nerve impulses and the process of muscle contraction. Calcium and magnesium deficiencies may also give rise to muscle twitching.
- Potassium deficiency which may be accompanied by muscle weakness.
- Alcohol abuse which may affect parathyroid hormone which is responsible for calcium regulation. Alcoholism can also cause magnesium deficiencies. Excessive use of alcohol causes dehydration due to the diuretic effect of alcohol. Cirrhosis and liver failure may also cause leg cramps.
- Smoking contributes to peripheral vascular disease and chronic obstructive airway disease both of which reduce the oxygenation of the blood.
- Diarrhea may cause leg cramps at night due to dehydration and the loss of water and electrolytes.
- Kidney failure and renal disorders like Addison’s disease may also result in dehydration and water and electrolyte loss.
- Anemia – poor oxygen supply to the leg muscles may result in anerobic metabolism triggering leg cramps.
- Peripheral vascular disease (PVD) – varicose veins, artherosclerosis and other causes of poor circulation to the legs and feet resulting in reduced oxygenation of the muscle tissue of the leg and feet. Other symptoms that may be noticed in peripheral vascular disease is swollen legs, skin discoloration and venous ulcers.
- Claudication is the calf muscle pain which is a symptom of peripheral vascular disease and may or may not be accompanied by leg cramps. Claudication should not be mistaken for regular muscle cramps of the leg and is a sign of a circulatory disorder including deep venous thrombosis (DVT) and should be investigated immediately.
- Diabetes is known to contribute to leg muscle cramping and this is further aggravated by the use of diabetic medication as well as circulatory disorders as a complication of uncontrolled diabetes, including diabetic neuropathy.
- Autoimmune disorders like sarcoidosis.
- Lead poisoning is known for muscle cramping and can affect muscles throughout the body.
- Exposure to extreme cold or frostbite can cause leg muscle cramps but other symptoms like a pale to blue discoloration of the skin, numbness or tingling may also be noticed.
- Neuromuscular and neurological disorders like Parkinson’s disease and dystonia may cause involuntary muscle contractions (chorea).
- Fibromyalgia and infections like cellulitis may cause significant leg pain and should not be mistaken for leg cramps.
1. Cramps in the Leg. Patient UK
2. Leg Cramps. Wrongdiagnosis
Article reviewed by Dr. Greg. Last updated on November 4, 2009