Prolactin dysregulation in women with subclinical hypothyroidism: effect of levothyroxine replacement therapy.
This study investigated the effect of levothyroxine treatment on serum prolactin (PRL) levels in women with subclinical hypothyroidism. Sixty-six women (mean age, 58.5 +/- 1.3 years) with confirmed subclinical hypothyroidism (mean thyrotropin [TSH], 11.7 +/- 0.8 mIU/L) were randomly assigned to receive levothyroxine or placebo for 48 weeks. Based on blinded TSH monitoring, physiologic levothyroxine replacement (85.5 +/- 4.3 microg/d; TSH, 3.1 +/- 0.3 mIU/L) was ascertained throughout the study. PRL levels were measured before and after administration of thyrotropin-releasing hormone (TRH) at baseline, after 24 and 48 weeks. Sixty-three of the 66 women completed the study. At baseline, basal PRL levels were elevated in 19% of the patients. None of the patients reported menstrual disturbances, infertility, or galactorrhea. In the levothyroxine group (n = 31) basal and peak PRL levels were significantly reduced after 24 and 48 weeks (p = 0.03 and p = 0.001). Mean changes in PRL levels differed significantly between the two treatment groups after 24 weeks (p = 0.03 and p = 0.01). The treatment effect was more pronounced in patients with PRL and TSH levels above the median at baseline (i.e., PRL > 16 ng/mL; TSH > 11 mIU/L). Based on this double-blinded, placebo-controlled study we demonstrate that in subclinical hypothyroidism PRL regulation is altered with elevated basal and stimulated PRL levels, and that physiologic levothyroxine treatment restores PRL concentrations.
Meier
Christian
C
Division of Endocrinology, Diabetology, and Clinical Nutrition, Department of Internal Medicine, University Hospitals, Basel, Switzerland. meierchr@datacomm.ch
Christ-Crain
Mirjam
M
Guglielmetti
Merih
M
Huber
Peter
P
Staub
Jean-Jacques
JJ
Müller
Beat
B
D004311:Double-Blind Method; D005260:Female; D006801:Humans; D007037:Hypothyroidism / Q000097:blood* / Q000188:drug therapy*; D010919:Placebos; D011388:Prolactin / Q000097:blood*; D012016:Reference Values; D013972:Thyrotropin / Q000097:blood; D013974:Thyroxine / Q000097:blood / Q000627:therapeutic use*; D013997:Time Factors; D014284:Triiodothyronine / Q000097:blood
D010919:Placebos; D014284:Triiodothyronine; D011388:Prolactin; D013972:Thyrotropin; D013974:Thyroxine