Muscle Cramps Do Not Improve With Correction of Vitamin D Insufficiency

Minimal treatment options exist for idiopathic muscle cramps.

We evaluated whether correction of vitamin D insufficiency relieved muscle cramps in postmenopausal women.

We conducted a post hoc analysis of a randomized, double-blind, placebo-controlled trial at a single academic medical center in the Midwest to evaluate the benefits of treating vitamin D insufficiency. Two hundred thirty postmenopausal women participated. Eligible women were ≤75 years old, 5 years past menopause or oophorectomy, or ≥60 years if they had previously undergone hysterectomy without oophorectomy. Women had vitamin D insufficiency at baseline (25-hydroxyvitamin D 14-27 ng/mL). We excluded subjects with a glomerular filtration rate <45 mL/minute.

Participants completed food diaries, laboratory studies, and functional tests including the Timed Up and Go test, Physical Activity Scale for the Elderly, Health Assessment Questionnaire (a measure of disability), and pain scores. Subjects recorded muscle cramp frequency and severity using a standardized form at 6 visits over 1 year.

During the trial, over half of participants (n=121, 53%) reported muscle cramps. Despite unequivocal vitamin D repletion, vitamin D had no effect on muscle cramps. Pain levels, disability, and dietary potassium predicted presence of cramps. Serum albumin and physical activity were inversely associated with, and disability was positively associated with, severity of muscle cramps.

Further studies are needed to evaluate the link between pain, disability, dietary potassium intake, and muscle cramps.