Endocrine Abstracts

Aim: To determine the prevalence of hyperprolactinaemia in patients with newly diagnosed subclinical and overt hypothyroidism, and to investigate the change in PRL levels during and after the treatment.

Methods: In this study were enrolled 100 patients, which have been diagnosed with hypothyroidism during a 2 year period, in ‘IKEDA’ hospital, DC ‘Med.al’ and DC ‘La vita’, and 100 healthy persons as controls. Lactating and pregnant women, patients with medical reasons for having elevated PRL levels, and persons with kidney and or liver disease were excluded from the study. Serum levels of thyrotropin (TSH), free thyroxine, free triiodothyronine and prolactin (PRL) were measured and correlation of PRL levels with the severity of hypothyroidism (overt or subclinical) was performed.

Results: Thirty-three patients (27 women, 6 men, mean age 42.7±14.1 years) had overt hypothyroidism. Sixty-seven patients (58 women, 9 men, mean age 40.2±12.3 years) had subclinical hypothyroidism. One hundred healthy persons (88 women, 12 men, mean age 41.8±10.5 years) participated as controls. The same blood tests were repeated in patients after normalization of TSH levels with L-thyroxine treatment. The PRL levels resulted elevated in 31% of patients with overt hypothyroidism, and in 20% of patients with subclinical hypothyroidism. PRL levels decreased to normal in all patients after thyroid functions normalized with L-thyroxine treatment. In the hypothyroid patients (overt and subclinical) a positive correlation was found between TSH and PRL levels (r=0.203, P=0.001).

Conclusion: PRL levels are altered in both overt and subclinical hypothyroidism, but they normalize after normalization of TSH, with appropriate L-thyroxine treatment.

Keywords: Prolactin, overt hypothyroidism, subclinical hypothyroidism, hyperprolactinaemia