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Calcium and vitamin D supplementation and risk of kidney stone formation in postmenopausal women.

INTRODUCTION
Calcium and vitamin D are essential structural components of the skeletal system, which prevent osteoporosis after menopause. However, there is a controversial debate on the association between the intake of calcium and vitamin D supplements and the increased risk of formation of kidney calculi in postmenopausal women. which yet have to be confirmed. This study aimed to compare the metabolic changes after supplementation of calcium and vitamin D and examine the risk of stone formation.


MATERIALS AND METHODS
Fifty-three postmenopausal women referred to rheumatology clinic who had no history of kidney calculi, bone diseases (apart from osteoporosis), metabolic, and rheumatic disorders and had not been receiving calcium, diuretics and calcitonin were investigated. Renal ultrasonography and blood tests were performed and the urine calcium levels were measured for a period of 24 hours for all patients. The examinations were repeated after a 1- year period of treatment with supplemental calcium (100 mg/d) and vitamin D (400 IU/d) and compared with the data before the treatment.


RESULTS
After 1 year, asymptomatic lithiasis was confirmed in 1 of 53 patients (1.9%) using ultrasonographic examination. No significant differences were found between the 24-hour urine and blood calcium levels before and after the treatment.


CONCLUSIONS
Our findings showed that oral intake of calcium and vitamin D after 1 year has no effect on the urinary calcium excretion rate and the formation of kidney calculi in postmenopausal women.