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 or at the
University of Wisconsin Hospitals and Clinics. 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.
This is a randomized, double-blind, placebo-controlled trial to determine if oral vitamin D
administration reduces the number or severity of nocturnal leg cramps, compared to placebo.
Symptom diaries will be used throughout the study to assess frequency and severity of
cramps. We will enroll a total of 70 men and women at least 50 years of age who have
nocturnal leg cramps at least twice weekly and have previously received quinine for this.
Those meeting baseline laboratory criteria and who report at least two leg cramps per week
in a two-week "diary run-in" period will be randomized to vitamin D or placebo. Baseline,
mid-study, and final laboratory testing will assess any changes in 25-hydroxyvitamin D and
related variables (25-hydroxyvitamin D is the best measure of vitamin D status.) The time
from the beginning of the diary run-in through the final dose of drug and last labs,will be
about 14 weeks.
Optimal vitamin D status for health is unknown, although many experts aim for serum
25hydroxyvitamin D of 35-40 ng/ml. Subjects in this study randomized to vitamin D 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. Based on published literature on the ability
of vitamin D to raise serum 25OHD over time, we estimate that the loading doses will "boost"
levels after 10 days by an increment of ~40ng/ml (up to ~65 ng/mL total, starting with a
typical person's baseline of 25ng/ml). This achieved level of 65 is within the reference
range of our VA's reference range of 20-100. (In the PI's experience, most veterans without
special D supplementation have baseline levels between 15 and 40).
- One or more prescription for quinine at the Madison VA in the last 5 years, or else
be a UWHC (U Wisconsin Health Clinics) patient whose UWHC medication list had quinine
listed in the last five years
- At least 50 years of age, with women being past menopause. This is defined as the
woman reporting no periods in the last 12 consecutive months or longer.
- Leg cramps listed in medical record,
- Ability & willingness to give informed consent,
- Stable estimated GFR >35 ml/min for the prior 6 mos,
- No change in diuretic therapy in last 3 months,
- Stable pattern of two or more cramps per week for past three months,
- Ability to complete daily diary entry,
- Post-consent: serum 25-OH of 20-45 ng/mL, albumin- corrected calcium <10.3 mg/dL, and
urine calcium/creatinine ratio <0.25.
- Not receiving primary care at Madison VAMC, or at UWHC
- Hyperparathyroidism (1°, 2°, or 3°),
- Osteomalacia ,
- Paget's disease,
- Metastatic cancer,
- Taking vitamin D 50,000 units capsules,
- Serum Ca++ >10.3 mg/dL in subject chart,
- Sarcoidosis or tuberculosis, and
- Peripheral vascular disease or other condition confounding assessment of cramps.