Endocrine Abstracts

Introduction

Among other organic functions, Prolactin (PRL) can influence metabolism.

Aim

To evaluate basal glucose metabolism in women with prolactinoma, according to menstrual cycle, presence of hyperprolactinemia, and dopamine agonist (DA) treatment.

Material and methods

Cross-sectional study of 17 women with microprolactinoma and 11 healthy controls. Variables evaluated: PRL, FSH, LH, estradiol, GH, IGF1, fasting glucose and insulin, Homeostatic Model Assessment (HOMA), HOMA-beta, body mass index (BMI), waist, hip, and waist-to-hip ratio (WHR). Group comparison between controls and patients with: (I) normal (NPRL, n = 6) and elevated PRL (EPRL, n = 11), (II) eumenorrhea (EU, n = 10) and oligomenorrhea (OLIGO, n = 7), and (III) bromocriptine (BC), cabergoline (CAB, n = 5) or no DA (NDA, n = 7) treatment.

Results

(I) Comparisons between NPRL, EPRL and controls: WHR was higher in NPRL (0.89 ± 0.04) than controls (0.80 ± 0.09; P = 0.0292). GH levels were lower in EPRL (0.50 ± 0.38 ng/ml) than controls (1.76 ± 1.17 ng/ml; P = 0.0275). (II) Comparisons between EU, OLIGO, and controls: PRL levels were higher in OLIGO (83.74 ± 54.04 ng/ml) than controls (13.82 ± 5.74 ng/ml; P = 0.0017). WHR was higher in EU (0.87 ± 0.05) and OLIGO (0.87 ± 0.05) than controls (P = 0.0380). GH levels were lower in EU (0.50 ± 0.43 ng/ml) than controls (P = 0.0210). (III) Comparisons according to DA treatment: CAB had higher PRL levels (77.08 ± 57.18 ng/ml) than controls (P = 0.0085). BC had lower fasting glycemia than CAB (77.0 ± 7.6 vs. 89.4 ± 3.6 mg/dl; P = 0.0220) and NDA (89.4 ± 5.2 mg/dl; P = 0.0021). HOMA-beta was higher in BC (P = 0.0347). GH levels were lower in NDA (0.41 ± 0.32 ng/ml) than controls (P = 0.0439). There were no other significant differences in variable comparisons between groups. Linear regression models did not show influence of GH on clinical-biochemical parameters of the patients. The influence of PRL and estradiol suggested by linear regression models was not confirmed by multivariate analyses, which only corroborated the influence of BC treatment on fasting glycemia (r² = 0.6159; P = 0.0020).

Conclusions

Patients with EPRL, NPRL, eumenorrhea, and oligomenorrhea had changes in WHR and GH levels. Treatment with BC was the main influence on fasting glucose. The authors emphasize the need for metabolic evaluation of patients with microprolactinoma and, despite the small sample size, our data indicate special attention to GH assessment, aiming at early detection of GH deficiency.