July - September 2005, Volume 1, Issue 3

Grigorie D, Neacsu E, Marinescu M, Dumitrache L, Popa O

25-hydroxyvitamin D and parathyroid hormone status in 834 postmenopausal women with osteoporosis

Acta Endo (Buc) 2005, 1 (3): 369-376
doi: 10.4183/aeb.2005.369

Vitamin D is essential in efficient absorption of calcium and normal mineralization of bone. Severe vitamin D deficiency produces impairment of bone mineralization and osteomalacia. Less severe vitamin D deficiency, called vitamin D insufficiency or inadequacy, causes secondary hyperparathyroidism, increased bone turnover and bone loss. The aims of our study were: the evaluation of vitamin D status and its seasonal variation in postmenopausal women with osteoporosis, from Romania; we studied also the relationship between vitamin D and parathyroid hormone serum concentrations in order to establish the threshold level of vitamin D which determines secondary hyperparathyroidism. The study was performed on 834 postmenopausal (natural or surgical) women who attended the National Osteoporosis Center and were diagnosed with osteoporosis using dual absorptiometry with X ray (DEXA). None was receiving vitamin D supplementation and they were not taking drugs affecting bone and mineral metabolism and were not suffering from such diseases. Estimation of vitamin D and parathyroid hormone status was made by determining 25-hydroxyvitamin D (25OHD) and PTH-intact (PTH) serum concentrations from a single blood sample using immuno-enzyme methods. The results were compared using Student? t test for unpaired values and linear regression to establish the correlation. All data were expressed as mean value ? standard deviation and a value of p<0.05 was considered as statistically significant. In a previous study we reported for premenopausal normal women the mean value for 25OHD at 26.58?10ng/ml. At the same time, we defined the vitamin D deficiency as the levels below 12 ng/mL, and the insufficiency of vitamin D (vitamin D inadequacy) as the values between 12 and 26.58 ng/mL. The mean serum 25OHD concentration for our study group was 20.04?144.22 mg/mL. We defined arbitrary values (using data from international studies) for 25OHD serum levels to estimate the prevalence of vitamin D deficiency and vitamin D inadequacy in our study group. In 834 postmenopausal women with osteoporosis, living in Romania, without vitamin D supplementation or pharmacological therapy to treat or prevent osteoporosis, the prevalence of vitamin D deficiency was 32.2% and the prevalence of vitamin D inadequacy was 42.3%. Seasonal variation of 25OHD was found statistically significant (p<0.05), with lower values at the end of winter. Statistical tests applied to results have shown a significant negative correlation between PTH and 25OHD serum levels (p<0.001) and established the cut-off concentration for 25OHD which determine secondary hyperparathyroidism at 20 ng/mL. Our data underscore the need for adequate vitamin D supplementation in women with osteoporosis.

Keywords: 25OHD deficiency; 25OHD inadequacy; secondary hyperparathyroidism; postmenopausal women, osteoporosis

Correspondence: Daniel Grigorie, Endocrinology Department, ?Carol Davila? University of Medicine and Pharmacy, 34-36 Bd. Aviatorilor, 011863, Bucharest, Romania, Phone: +4021 300 36 32, Fax: +4021 3176495, e-mail: grigorie.d@home.ro