Parathormone-Related Peptide Is Not Associated with Bone Mineral Density in Eugonadal Prolactinoma

Objective: One of many theories for the cause of osteoporosis in prolactinoma is the increased level of the parathyroid hormone-related peptide. We aimed to assess the parathyroid hormone-related pep- tide levels and its potential effects on bone mineral density in patients with eugonadal prolactinoma.

Methods: We enrolled 29 eugonadal prolactinoma patients and 31 controls. Serum prolactin, thyroid function tests, calcium, phosphorus, albumin, gonadal steroids, parathyroid hormone, 25-OH vita- min D, alkaline phosphatase, 24-hour urine calcium, parathyroid hormone-related peptide, and bone mineral density were measured.

Results: No statistically significant difference was observed in parathyroid hormone-related peptide levels between the prolactinoma and the control groups (P = .288). The parathyroid hormone-related peptide levels were significantly higher in men in both groups (P < .05). No relationship was observed between the parathyroid hormone-related peptide levels and bone mineral density in g/cm2 for lum- bar vertebrae, femur, and radius (P > .05). Although there was also no significant correlation between parathyroid hormone-related peptide and Z scores of lumbar vertebrae and femur (P > .05), Z scores of radius were significantly correlated with parathyroid hormone-related peptide (P = .001, r = -0.575).

Conclusion: To the best of our knowledge, contrary to hypotheses that the elevated level of para- thyroid hormone-related peptide may be one of the factors contributing to osteoporosis in prolac- tinoma patients, this is the first study revealing that parathyroid hormone-related peptide has no significant impact on osteoporosis in eugonadal prolactinoma patients. Furthermore, this is the first study to demonstrate gender differences in physiological parathyroid hormone-related peptide lev- els. However, additional studies with large samples are required to confirm these findings.

Cite this article as: Okyar Baş A, Cinel M, Demir Ö. Parathormone-related peptide is not associated with bone mineral density in eugonadal prolactinoma. Endocrinol Res Pract. 2023;27(3):158-163.