INTRODUCTION: Osteopenia and osteoporosis because of hyperprolactinaemia caused 
by prolactinoma may be followed by an increased risk of fracture. There are no 
data on the bone effects of functional hyperprolactinaemia. The aim was to 
assess the influence of hyperprolactinaemia of various origins on bone turnover 
and density in different skeletal sites.
MATERIAL AND METHODS: The study was carried out in 75 women (aged 30.53 +/- 
7.8): Group I--32 women with prolactinoma and Group II--43 women with functional 
hyperprolactinaemia. Both groups of patients were subdivided into those with 
hypogonadism and those with normal gonadal function. The control group consisted 
of 29 healthy women aged (33.59 +/- 4.7). In all subjects PRL and bone turnover 
markers (BAP, OC, ICTP) were studied. BMD measurements (lumbar spine, forearm, 
proximal femur and total body) were carried out using DXA.
RESULTS: Higher PRL concentrations were observed in patients than in controls. 
The values of bone turnover markers (BAP, ICTP) were shown to be higher in 
patient groups and subgroups than in controls. In patients with prolactinoma 
lumbar spine BMD was lower than in patients with functional hyperprolactinaemia 
and controls. Total body BMD was also lower, albeit to a lesser extent.
CONCLUSIONS: Hyperprolactinaemia caused by prolactinoma in women influences bone 
metabolism unfavourably, more by the impact on the activity of bone turnover 
markers than on BMD. This provides an opportunity for earlier assessment of bone 
metabolism disturbances before the BMD changes can be observed. Functional 
hyperprolactinaemia does not determine such a harmful effect on bone metabolism 
as hyperprolactinemia due to prolactinoma.