All 25-hydroxyvitamin D-deficient Indian postmenopausal women do not have secondary hyperparathyroidism

This study shows a high 25-hydroxyvitamin D deficiency among postmenopausal women accompanying secondary hyperparathyroidism. However, a sizable number of subjects did not have secondary hyperparathyroidism despite having low 25-hydroxyvitamin D levels. This condition arises a research question in clinical practice needed to be addressed in the future.

The present study was attempted to determine the prevalence of secondary hyperparathyroidism and also to analyze the mean value (cutoff) of 25-hydroxyvitamin D from where the PTH begins to rise in Indian postmenopausal women.

A cross-sectional study including 334 postmenopausal women attending the outpatient department (MOPD) of Lok Nayak Hospital, New Delhi, between July 2008 and June 2010. Institutional ethical approval was obtained for this study. The apparently healthy postmenopausal women and attendees of the patients were included in the study. Post-thyroidectomy, thyroid illness, pregnant women, subjects taking drugs that can affect bone mineral metabolism, such as glucocorticoids, antitubercular therapy, antiepileptic, and 25-hydroxyvitamin D supplement were excluded from the study. BMD parameters such as PTH and 25(OH)D were measured by using commercial kits from DiaSorin, USA, and blood chemistry was evaluated by standard methods from the central facility of the center. Dietary calcium was analyzed by applying a food frequency questionnaire by a trained dietician.

Mean (SD) age of the subjects was 56.4 ± 7.7 years. The mean BMI was 24.7 ± 5.5 kg/m². The baseline biochemical investigations such as total bilirubin, liver function test (LFT), kidney function test (KFT), calcium, phosphorous, total protein, and serum albumin were in reference range except alkaline phosphatase (ALP). The mean values of 25(OH)D and PTH were 12.95 ± 8.08 ng/ml and 91.60 ± 75.56 pg/ml respectively. The 24-h dietary calcium intake was 487.06 ± 239.36 mg/24 h. 25-hydroxyvitamin D deficiency was found in 277 subjects (82.93%) and was inversely related to PTH. Forty-three subjects had 25-hydroxyvitamin D levels between 20 and 29 ng/ml (12.87%), and only 14 subjects (4.19%) had optimum 25-hydroxyvitamin D levels. Secondary hyperparathyroidism was found in 235 (70.35%) subjects; however, it was not found in 30%.

Majority of postmenopausal women of India had 25-hydroxyvitamin D deficiency with raised PTH levels. The cutoff point of 25-hydroxyvitamin D at which PTH began to rise was found at 25 ng/ml which seems similar to that of the Caucasians.