Biomarkers of bone turnover and bone mineral density in hyperprolactinemicamenorrheic women

We tested the hypothesis that biomarkers of bone resorption are increased i n hyperprolactinemic amenorrheic patients with estrogen (E) deficiency, aug menting the possible risk of developing osteoporosis. Fifty hyperprolactine mic patients with amenorrhea of more than 12 months and with low serum E2, as well as 30 healthy fertile women (controls), matched for age and body ma ss index, participated in this study. Bromocriptine was administered orally to hyperprolactinemic patients and blood and urine samples were collected before and 12 weeks after treatment. Serum osteocalcin (OC) and bone-specif ic alkaline phosphatase (B-ALP), reflecting bone formation, and urinary deo xypridinoline (D-Pyr) and N-telopeptide of type 1 collagen (NTX) excretion, reflecting bone resorption, were measured using direct immunoassays. Hyper prolactinemic patients had higher (p < 0.0005) levels of all the biomarkers compared to control values: (OC, 22 +/- 1.2 [SE] vs. 14 +/- 0.99 ng/ml (+5 7 %); B-ALP, 14.2 +/- 0.7 vs. 7.5 +/- 0.8 ng/ml (+89%); D-Pyr, 8.8 +/- 0.6 vs. 3.2 +/- 0.3 nmol/mmol creatinine (+175 %) and NTX, 65 +/- 5.1 vs. 25 +/ - 3.2 nmol bone collagen equivalent (BCE)/mmol creatinine (+160%)). These r esults were associated with significantly decreased lumbar spine bone miner al density (LS-BMD), measured by dual energy X-ray absorptiometry (DEXA). T reatment of hyperprolactinemia with bromocriptine restored normal values of bone formation and resorption markers. In conclusion, hyperprolactinemia w ith estrogen deficiency exhibits a significant increase of bone resorption which is associated with a significant decrease of LS-BMD. These changes ma y subject the patient to the possible risk of developing osteoporosis.