Thyroxine treatment modified in infertile women according to thyroxine-releasing hormone testing: 5 year follow-up of 283 women referred after exclusion of absolute causes of infertility.
BACKGROUND
Mild hypothyroidism may contribute to disturbed reproductive function. We hypothesized that frequent thyroxine-releasing hormone (TRH) testing to fine-tune thyroxine (T4) therapy instituted upon every TRH-induced thyroid-stimulating hormone (TSH) rise above the mean of a healthy population (i.e. 15 mIU/l) would improve fecundity compared with historical data.


METHODS
In a cohort of 283 infertile women followed over 5 years, we assessed (i) pregnancy, abortion and delivery rates, (ii) thyroid function over time in women who conceived compared with those who did not, and (iii) various thyroid parameters with respect to fertility.


RESULTS
Overall conception rate of 37% was higher (P < 0.05) than previously reported and independent of thyroid function prior to T4 therapy, thyroxine dose or elevated thyroid autoantibodies. Never achieving basal TSH <2.5 IU/l or TRH-stimulated TSH <20 mIU/l with T4 therapy resulted in lower conception rates (P < 0.05). Median time to conception was 6 months, but 18 months in women who declined TRH testing (P < 0.02). Overall abortion rate was 9%. Only first trimester miscarriages occurred.


CONCLUSIONS
Based on the presented protocol, high pregnancy and parturition rates were observed. Whether this is due to early T4 therapy remains to be determined. Abortions appeared to be associated with higher TSH but not with elevated thyroid antibodies.
Raber
W
W
Department of Medicine III, Division of Endocrinology and Metabolism, University of Vienna, Vienna, Austria. wolfgang.raber@gmx.at
Nowotny
P
P
Vytiska-Binstorfer
E
E
Vierhapper
H
H
D000022:Abortion, Spontaneous / Q000453:epidemiology; D000328:Adult; D001723:Birth Rate; D015331:Cohort Studies; D005260:Female; D005306:Fertilization; D005500:Follow-Up Studies; D006801:Humans; D015994:Incidence; D007247:Infertility, Female / Q000097:blood* / Q000188:drug therapy* / Q000503:physiopathology; D011247:Pregnancy; D018873:Pregnancy Rate; D011261:Pregnancy Trimester, First; D012017:Referral and Consultation; D013961:Thyroid Gland / Q000187:drug effects / Q000503:physiopathology; D013973:Thyrotropin-Releasing Hormone / Q000097:blood*; D013974:Thyroxine / Q000627:therapeutic use*; D013997:Time Factors
D013973:Thyrotropin-Releasing Hormone; D013974:Thyroxine