INCIDENCE AND IMPORTANCE OF THYROID-DYSFU NCTION IN INFERTILE WOMEN PARTICIPATING IN A PROGRAM FOR ASSISTED REPRODUCTION

Within 16 months, successively 227 infertile women (median 32 years) a ttending the unit for assisted reproduction at the Women's University Hospital, were examined for infertility factors. Endocrine cycle-depen dent hormone analysis was carried out in a preceding untreated cycle b efore infertility treatment with in vitro fertilisation/embryo transfe r (IVF/ET), intracytoplasmatic sperm injection (ICSI) or ovarian stimu lation with gonadotropins/homologous intrauterine insemination (IUI). Simultaneously thyroid ultrasound and endocrine thyroid tests includin g total triiodithyronine (TT3), total thyroxine (TT4), thyroglobulin ( TBG), thyroid antibodies and thyroid stimulating hormone (TSH) before and after stimulation with thyroid releasing hormone TRH (200 mu g i.v .), were performed. While the diagnostic cycle was done, 27 patients ( 11.9%) were already on therapy with thyroxine for treatment of mainly subclinical hypothyroidism, suppression therapy of goitre or to preven t redevelopment of goitre after surgery. These women were excluded fro m further analysis. 38 (19.8%) patients of the remaining 192 patients were diagnosed to have subclinical hypothyroidism (Delta TSH <12.5 mu U/ml). 38 (19.8%) patients were hyperthyroid (Delta TSH <2,5 mu U/ml) although only one woman had clinical symptoms of hyperthyroidism. No p atient suffered from clinical hypothyroidism. Already basal TSH were s ignificantly different among the euthyroid, hyperthyroid and subclinic al hypothyroid groups (p < 0.003). 77.1% (n = 148) of the 192 patients included in the evaluation had thyroid ultrasound and dependent on th e result in 18.2% (n = 35) of the women thyroid scintigraphy in the de partment: for nuclear medicine of the university was initiated. The in cidence for goitre was 30.4% (n = 143) in the euthyroid group while in the hyperthyroid group the incidence of 77% was more than two times h igher. Patients with subclinical hypothyroidism had a significantly lo wer incidence of goitre (11.1%; p < 0.01). Moreover, the lowest median (99m)technetium (Tc) uptake in the thyroid scintigraphy (normal < 2.5 %) was in the subclinical hypothyroid patients (2.3%). Smelters had si gnificantly more goitres than non-smokers (37.2 vs. 25.4%; p < 0.04). In the follow-up period (11-27 months) altogether 64 of the 192 patien ts became pregnant. The spontaneous conception rate was 6.3%, whereas 27% of the patients became pregnant mainly after infertility treatment with IVF/ET or gonadotropin stimulation/IUI. There was a tendency tha t in patients classified as subclinical hypothyroid the pregnancy rate is higher in comparison to euthyroid and hyperthyroid patients (36.8% vs. 32.9% and 27.3%), although no statistical difference was achieved . The general recommendation for thyroid hormone substitution therapy in subclinical hypothyroidism and infertility;cannot be upheld. If cli nical hypo- or hyperthyroidism (incidence < 5%) is to be excluded in f emale infertility, determination of basal TSH alone is sufficient.