Time-resolved fluoroimmunoassay compared with radioimmunoassay of luteinizing hormone.

OBJECTIVE

To determine if fluoroimmunoassay (FIA) of serum luteinizing hormone (LH) is more useful clinically than a conventional radioimmunoassay (RIA) because it has been suggested that FIA closely reflects biological activity.

DESIGN

Comparison of serum LH measurements by RIA and FIA during various perturbations in normal ovulatory women and in women with polycystic ovarian syndrome (PCOS).

SETTING

Normal ovulatory subjects were healthy volunteers and women with PCOS were untreated and newly diagnosed outpatients in our Reproductive Endocrinology/Infertility Clinic, Women's Hospital, at the Los Angeles County+University of Southern California Medical Center.

PARTICIPANTS

Fifty-three normal ovulatory women, ages 20 to 35, and 27 women with PCOS, ages 21 to 35. All were in good health and received no other medications during the study period.

RESULTS

Fluoroimmunoassay of serum LH reflected status of known altered bioactivity better than with a conventional RIA. This was most evident during conditions of gonadotropin suppression and in patients with PCOS. An excellent correlation was found between values of FIA and RIA.

CONCLUSIONS

The measurement of LH by FIA is clinically useful, specifically when a change in biological activity of LH is sought.