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Endocr Pract. 1999 Sep-Oct;5(5):229-32.

Single-monthly-dose vitamin D supplementation in elderly patients.

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Department of Obstetrics & Gynecology, Texas Tech University, Health Science Center School of Medicine, Amarillo, Texas, USA.



To determine the serum levels of calcidiol and calcitriol in 2 men and in 21 postmenopausal, primarily elderly women receiving hormone replacement therapy, orally administered calcium citrate, and an additional supplement of 50,000 IU of vitamin D (1.25 mg of cholecalciferol) once monthly for various periods.


We determined plasma calcidiol and calcitriol levels at various times, ranging from -1 to +60 days after intake of a single dose of 1.25 mg of vitamin D in 10 initial or short-term users (1 to 6 months) and in 13 women who had been using this monthly regimen for several years. The primary concerns were the safety and adequacy of the blood levels achieved with a regimen that encouraged compliance.


In long-term users of monthly vitamin D regimens, calcidiol levels were usually slightly in excess of the upper limit of normal (that is, >52 ng/mL [>130 nmol/L]) at all times throughout the month; in contrast, calcitriol levels exceeded the normal range (8 to 52 pg/mL [19 to 125 pmol/L]) only once in 18 samplings. In short-term users, calcidiol levels exceeded the normal range only once shortly after intake, and no calcitriol level exceeded the normal range.


Once-a-month dosage of 50,000 IU (1.25 mg) of vitamin D in elderly women receiving hormone replacement therapy plus supplemental calcium and uncontrolled generic multivitamin intake yields calcitriol levels within the normal range, even after years of use of this regimen. Calcidiol levels exceeded the normal range at all times in long-term users but only once in short-term users. Calcidiol concentrations, however, were found to be far below levels (>150 ng/mL [>375 nmol/L]) that might produce hypercalciuria or hypercalcemia.


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