Skeletal muscle cramps may be caused by
muscle fatigue or a lack of
electrolytes such as
sodium (a condition called
hyponatremia),
potassium (called
hypokalemia), or
magnesium (called
hypomagnesemia). Some skeletal muscle cramps do not have a known cause.
hyperflexion,
hypoxia, exposure to large changes in temperature, dehydration, or
low blood salt. Muscle cramps can also be a symptom or complication of
pregnancy;
kidney disease;
thyroid disease;
hypokalemia,
hypomagnesemia, or
hypocalcaemia (as conditions);
restless legs syndrome;
varicose veins; and
multiple sclerosis. As early as 1965, researchers observed that leg cramps and restless legs syndrome can result from excess
insulin, sometimes called
hyperinsulinemia.
Nocturnal leg cramps Leg cramps might occur during the night or less commonly while resting. These are involuntary muscle contractions that occur in the
calves,
soles of the feet, or other muscles in the body. The duration is variable, with cramps lasting anywhere from a few seconds to several minutes. Muscle soreness may remain after the cramp itself ends. These cramps are more common in older people. They happen quite frequently in teenagers and some people while exercising at night. Besides being painful, a nocturnal leg cramp can cause much
distress and
anxiety. The precise cause of these cramps is unclear. Potential contributing factors include
dehydration, low levels of certain minerals (
magnesium,
potassium,
calcium, and
sodium, although the evidence has been mixed), A lactic acid buildup around muscles can trigger cramps; however, they happen during anaerobic respiration when a person is exercising or engaging in an activity where the heartbeat rises. Medical conditions associated with leg cramps are cardiovascular disease, hemodialysis, cirrhosis, pregnancy, and lumbar canal stenosis. Differential diagnoses include
restless legs syndrome,
claudication,
myositis, and
peripheral neuropathy. All of them can be differentiated through careful history and physical examination.
Treatment induced Various medications may cause nocturnal leg cramps: •
Diuretics, especially potassium-sparing • Intravenous (IV)
iron sucrose •
Conjugated estrogens •
Teriparatide •
Naproxen •
Raloxifene • Long-acting
adrenergic beta-agonists (LABAs) • Hydroxymethylglutaryl-coenzyme A reductase inhibitors (HMG-CoA inhibitors or
statins)
Statins may sometimes cause
myalgia and cramps among other possible side effects.
Raloxifene (Evista) is a medication associated with a high incidence of leg cramps. Additional factors, that increase the probability of these side effects, are physical exercise, age, history of cramps, and
hypothyroidism. Up to 80% of athletes using statins experience significant adverse muscular effects, including cramps; the rate appears to be approximately 10–25% in a typical statin-using population. In some cases, adverse effects disappear after switching to a different statin; however, they should not be ignored if they persist, as they can, in rare cases, develop into more serious problems.
Coenzyme Q10 supplementation can help avoid some statin-related adverse effects, but currently, there is not enough evidence to prove its effectiveness in avoiding myopathy or myalgia. ==Treatment==