Vitamin D repletion does not alter urinary calcium excretion in healthy postmenopausal women

• Published in: BJU international Vol. 104; no. 10; pp. 1512 - 1516
• Main Authors: Penniston, Kristina L., Jones, Andrea N., Nakada, Stephen Y., Hansen, Karen E.
• Format: Journal Article
• Language: English
• Published: Oxford, UK Blackwell Publishing Ltd 01.11.2009; Wiley-Blackwell
• Subjects: Aged; Biological and medical sciences; calcium; Calcium - urine; Dietary Supplements; Female; Humans; Hypercalciuria - chemically induced; kidney stones; Medical sciences; Middle Aged; Nephrology. Urinary tract diseases; Osteoporosis - prevention & control; Postmenopause; Risk Factors; Urinary lithiasis; urolithiasis; Urolithiasis - chemically induced; vitamin D; Vitamin D - administration & dosage; Vitamin D - adverse effects; Vitamin D Deficiency - complications; Vitamin D Deficiency - drug therapy; Vitamins - administration & dosage; Vitamins - adverse effects; Human; Kidney disease; Excretion; Nephrology; Urinary system disease; Calciuria; Calcium; Healthy subject; Inorganic element; Urology; Urinary stone; Renal lithiasis; Vitamin D; Postmenopause; urolithiasis; Adult; Female; Woman; kidney stones
• ISSN: 1464-4096; 1464-410X
• DOI: 10.1111/j.1464-410X.2009.08559.x

OBJECTIVE To evaluate, in a posthoc analysis of a previous study, whether vitamin D repletion in postmenopausal women with insufficient vitamin D increases urinary calcium excretion, as vitamin D therapy might contribute to hypercalciuria and calcium stones in susceptible individuals, and the effect of vitamin D on the risk of urolithiasis warrants attention. SUBJECTS AND METHODS We recruited 18 women at ≥5 years after menopause who had vitamin D insufficiency (serum 25(OH)‐vitamin D, 16–24 mg/dL). We excluded women with a history of urolithiasis and kidney disease. Women had one calcium absorption study when vitamin D‐insufficient, received vitamin D therapy, and completed a second calcium absorption study when vitamin D‐replete. We fed subjects meals that mirrored the nutrient composition from self‐reported 7‐day diet diaries. To measure calcium absorption, we collected urine for 24 h during both visits. RESULTS We achieved vitamin D repletion in all women (25(OH)‐vitamin D before and after treatment, 22 and 63 mg/dL, respectively; P < 0.001). The mean calcium intake was 832 mg/day. Residual urine specimens were available for 16 women, allowing a measurement of 24‐h urinary calcium. Calcium excretion did not change after vitamin D therapy (212 before vs 195 mg/day after; P = 0.60). Of four women with hypercalciuria (>247 mg/day), calcium excretion decreased in three (377–312 mg/day, not significant). CONCLUSION Vitamin D supplementation did not increase the urinary calcium excretion in healthy postmenopausal women. Many stone formers are at risk of premature bone loss, vitamin D insufficiency, or both. Based on the present results we suggest a study of patients with hypercalciuria and nephrolithiasis to determine the risks of vitamin D therapy.