[Increase of PTH in post-menopausal osteoporosis]

Increased parathyroid values (PTH) serum values can be observed in postmenopausal women. However, the clinical repercussion and causes of this finding are poorly understood. This study has aimed to analyze the prevalence and conditions associated to the increased serum PTH levels in postmenopausal women with osteoporosis as well as their clinical characteristics.

Post-menopausal women with osteoporosis were included in the study. PTH, 25-hydroxyvitamin D (25OHD), 24-h urinary calcium, glomerular filtration rate (GFR) and calcium intake were evaluated. The prevalence of increased PTH serum values and its relationship with vitamin D deficiency and insufficiency, kidney failure, hypercalciuria and calcium intake deficiency were evaluated, these being conditions that may increase PTH secretion.

A total of 204 postmenopausal women with osteoporosis with a mean age of 64 years were included. Increase PTH levels (>65 pg/ml) were observed in 35% and 5 women had primary hyperparathyroidism. Women with increased serum PTH levels were older (67 ± 9 years) were old than those with normal PTH levels (63 ± 11 years) (P=0.03). PTH elevation was associated to calcium intake deficiency (<800 mg/d) in 81% of the women, to a vitamin D deficiency and insufficiency in 55% and 86%, respectively, renal insufficiency in 35% and hypercalciuria in 17% of the patients. These values, however, did not differ when compared with patients with normal PTH serum levels. Serum PTH levels were related to age (r=0.19, P=0.01) but not to 25OHD or GFR values.

One third of the post-menopausal women with osteoporosis had elevated PTH levels. This was due to primary hyperparathyroidism in 10%. The prevalence of conditions associated to the increase in PTH (reduced calcium intake, 25-hydroxyvitamin D, renal failure and hypercalciuria) is similar to that observed in women with normal PTH values.