Idiopathic cramps (the most common type)
Dehydration; volume depletion
Exercise-induced cramps
Pregnancy
Hemodialysis (volume and electrolyte shifts); ESRD
Muscle injury e.g. from sports; Exercise-associated muscle cramping; excessive running
Diabetes
Hypothyroidism, Hyperthyroidism
Hyponatremia
Hypocalcemia
Hypokalemia, hyperkalemia
Hypomagnesemia
Alkalosis (e.g. respiratory from hyperventilating or vomiting)
McArdle’s disease (glycogen storage disease: muscle fatigue, cramping, high CK)
Writer’s cramp
Ehlers Danlos (hypermobility) syndrome
Peripheral vascular disease; Vascular insufficiency; Claudication; Venous insufficiency
Celiac disease (from impaired calcium absorption)
Black widow spider bite
Medications: Statins, Intravenous iron sucrose, raloxifene, Naproxen, conjugated estrogens, nifedipine, inhaled beta agonists, thiazides, beta blockers, cisplatin, vincristine, oral contraceptives, others)
Lower motor neuron (injury, amyotrophic lateral sclerosis, compression)
Parkinson disease
Hypnic myoclonus; Sleep starts and myoclonic jerks
Myositis, myalgias
Periodic limb movement disorder
Restless leg syndrome
Peripheral neuropathy
Dystonias
Neurologic deficit
Compartment syndromes
Further Reading
J Clin Neuromuscul Dis. 2002 Dec;4(2):89-94. https://www.ncbi.nlm.nih.gov/pubmed/19078696