Evaluation of hormonal testing in the screening for in vitro fertilization (IVF) of women with tubal factor infertility.

PURPOSE

To evaluate the frequency of abnormal prolactin and thyroid stimulating hormone (TSH) test results in ovulatory women with tubal factor infertility who were screened for in vitro fertilization (IVF).

METHODS

Charts were identified from 112 ovulatory women with follicle stimulating hormone (FSH) < 20 mIU/ml who were diagnosed with tubal factor infertility and were screened for IVF with thyroid stimulating hormone (TSH) and prolactin levels. Women previously diagnosed with thyroid disease were subsequently excluded and 98 subjects remained. All subjects were determined to be ovulatory by biphasic basal body temperature (BBT) charts, luteal phase progesterone > 4 ng/ml, or endometrial biopsy revealing secretory endometrium. Results of cycle day 3 serum TSH and prolactin concentrations were recorded. The normal range for each test reflects the geometric mean +/- 2 standard deviations (i.e., 95% interval), as obtained from the reference laboratory. Under this construct, hypothesis tests were performed to determine whether or not our study population was consistent with the reference range of normal hormone levels. Under the null hypothesis (normal levels), we expected 5% of the TSH tests to be abnormal (i.e., high or low levels), and 2.5% of the prolactin tests to be abnormal (i.e., high levels). Exact bionomial confidence intervals and P-values were calculated. We also tested for age trend in the proportion of abnormal results.

RESULTS

Study subjects had an age range of 25-43. In the study group, 4 (0.041) out of the 98 women screened had abnormal TSH levels. Of these four abnormal TSH results, three were elevated (i.e., TSH > 4.6 microIU/ml) and one was low (i.e., TSH < 0.6 microIU/ml). The frequency of an abnormal TSH value was not significantly different from that expected from the reference laboratory normal values (95% CI 0.011, 0.101). Of the 98 subjects, 7 (0.071) had abnormal prolactin levels, which was significantly different from that expected from the reference laboratory normal values (95% CI 0.029, 0.142; P = 0.023). When stratified by age, there was no observed trend of abnormalities for TSH or prolactin levels with increasing age.

CONCLUSIONS

In ovulatory women presenting for IVF with tubal factor infertility, our results show that routine screening with a TSH test does not yield a significantly higher proportion of abnormal results than that expected from the reference laboratory normal values. However, prolactin level screening was found to yield a higher incidence of abnormal tests than expected from the reference laboratory normal values.