1. Research question: Does vitamin D reduce the frequency and severity of nocturnal leg
cramps in older persons who previously took quinine for leg cramps?
2. Experimental Design: This is a randomized, double blind, placebo controlled study of 70
men and women veterans receiving care at the Madison VA Medical Center(VAMC) or at the
University of Wisconsin Hospitals and Clinics (UWHC). Individuals age 50 or more who
have previously taken quinine for nocturnal leg cramps and meeting baseline criteria are
eligible to enroll. Enrollees meeting laboratory criteria, including low-normal vitamin
D levels, will undergo a 2-week "diary run-in" period to confirm cramp frequency. Those
who report two or more leg cramps in each week will continue in the study and will be
randomized to vitamin D or placebo. After a two-week wash-in, subjects will take a
vitamin D capsule (50,000 units) once daily for 10 days, followed by a once weekly
vitamin D (50,000 units) maintenance dose for 7 weeks. Subjects will record by diary the
number and severity of leg cramps from the start of the "diary run-in" until a week
after the last dose of study drug. Study investigators will call subjects at scheduled
intervals to assess compliance, tolerability, and diary use.
3. Major risks to subjects: No major risks are anticipated. Excessive vitamin D can
increase blood calcium levels (hypercalcemia), with symptoms such as thirst, nausea, and
weakness. However, symptomatic hypercalcemia has not been reported except for those
taking more than 40,000 units daily for several months. This is far above the cumulative
dose in our study.
4. Potential benefits: Subjects may not receive any benefit. Vitamin D may alleviate leg
cramps for subjects who receive it.
5. Consent Procedure: Flyers describing the study and telephone contact information will be
mailed to patients who have received quinine during the period 2002-2007. The PI or
Co-PI will return calls to describe the study and answer any questions. For persons
meeting preliminary (pre-lab) study criteria, two copies of the consent form will be
mailed, with the patient mailing back one signed consent to the PI.