Endocrine Abstracts

Background: The aim of this study was to compare the influence of medicamentous and physiological hyperprolactinemia on bone turnover in female rats.

Methods: Experimental animals (18 weeks old, Wistar female rats) were divided in the following groups: Group I: 9 rats, three week pregnant; Group II: ten female rats that were i.m. administrated Sulpirid (10 mg/kg) twice daily for three weeks; Group III: ten female rats that were i.m. administrated Sulpirid (10 mg/kg) twice daily for six weeks; Group IV: ten female rats, control group. Laboratory investigations included serum and urinary calcium, inorganic phosphorus, alkaline phosphatase and serum procollagen type 1 N-terminal propeptide (P1NP).

Results: Experimental animals in Group I (physiological hyperprolactinemia) compared to control group, displayed lower mean serum calcium (0.5±0.2 vs 1.12±0.04 mmol/l; P<0.001); higher mean serum phosphorus (2.42±0.46 vs 2.05±0.2 mmol/l; P<0.05); decreased urinary calcium (0.13±0.06 vs 0.39±0.18 mmol/mmol creatinine;P<0.001) and significantly increased P1NP (489.22±46.77 vs 361.9±53.01 pg/ml; P<0.001). Experimental animals in Group II (medicamentous hyperprolactinemia) had significantly decreased P1NP, compared to control group (309.6±36.74 vs 361.9±53.01 pg/ml; P<0.05). Prolongated medicamentous hyperprolactinemia (Group III) induced increased serum calcium (1.21±0.025 vs 1.12±0.04 mmol/l; P<0.05); decreased serum phosphorus (1.69±0.13 vs 2.05±0.2 mmol/l; P<0.001); decreased alkaline phosphatase (49.61±14.39 vs 77.07±22.6 U/l; P<0.01) and significantly decreased P1NP (291.7±71.03 vs 361.9±53.01 pg/ml; P<0.05).

Conclusions: Physiological hyperprolactinemia does not determine such harmful effect on bone metabolism as medicamentous hyperprolactinemia. Chronic medicamentous hyperprolactinemia displayes lower serum levels of P1NP, which reflects poor bone formation. Assessment of bone turnover markers in prolongated medicamentous hyperprolactinemia, provides an opportunity for earlier diagnosis of bone metabolism disturbances and should be considered as mandatory.

Declaration of interest: The authors declare that there is no conflict of interest that could be perceived as prejudicing the impartiality of the research project.

Funding: This research did not receive any specific grant from any funding agency in the public, commercial or not-for-profit sector.