The significance of a single serum LH measurement in women with cycle disturbances: discrepancies between immunoreactive and bioactive hormone estimates

• Published in: Clinical endocrinology (Oxford) Vol. 37; no. 5; p. 445
• Main Authors: Fauser, B C, Pache, T D, Hop, W C, de Jong, F H, Dahl, K D
• Format: Journal Article
• Language: English
• Published: England 01.11.1992
• Subjects: Adult; Biological Assay; Female; Humans; Immunoradiometric Assay; Luteinizing Hormone - blood; Menstruation Disturbances - blood; Polycystic Ovary Syndrome - blood; Polycystic Ovary Syndrome - diagnosis; Predictive Value of Tests; Testosterone - blood
• ISSN: 0300-0664; 1365-2265
• DOI: 10.1111/j.1365-2265.1992.tb02357.x

We evaluated the significance of single serum LH estimates (as assessed by radiometric assay (IRMA) and Leydig cell in-vitro bioassay (BIO)) for the diagnosis of polycystic ovary syndrome (PCOS) in women with infertility and cycle abnormalities. Hormonal and clinical comparisons between subgroups were made based on classification according to (a) rigid clinical and endocrine (excluding LH) characteristics of PCOS, (b) elevated IRMA-LH concentrations, (c) BIO-LH levels. In addition, androgen modulation of LH biopotency was studied in these patients. Ninety-nine women presenting at our infertility Unit with oligo/amenorrhoea. Of the total study group, 35 women were diagnosed positive as PCOS and 42 showed elevated IRMA-LH levels. Only 51% (n = 18) of PCOS patients showed elevated IRMA-LH levels, and in PCOS significantly higher levels of BIO-LH, androstenedione, oestrone, and BIO/IRMA-LH ratios were found as compared to non-PCOS patients. In the group with elevated IRMA-LH only 43% (n = 18) of subjects were diagnosed as PCOS, and no difference in BIO/IRMA-LH ratios was found. With increasing BIO-LH levels the probability of PCOS rises sharply (P < 0.001), whereas this probability is of only marginal significance (P < 0.06) for IRMA-LH. In the total study group a correlation is observed between serum testosterone (T) levels and IRMA-LH (r = 0.47), and BIO-LH (r = 0.51) concentrations. This correlation is absent comparing serum T and BIO/IRMA-LH ratios (r = 0.15). Results presented in this study indicate that (1) women with infertility and oligo/amenorrhoea classified based on signs of PCOS or IRMA-LH levels, exhibit different clinical and endocrine characteristics, (2) only 51% of PCOS women exhibit elevated IRMA-LH concentrations, and only 43% of women with elevated IRMA-LH were diagnosed as PCOS, (3) IRMA-LH levels are a poor predictor of PCOS, whereas the predictive value of BIO-LH is better, (4) elevated BIO/IRMA-LH ratios in PCOS are dependent on alterations in BIO-LH, rather than IRMA-LH concentrations, and (5) no correlation was observed between serum T levels and BIO/IRMA-LH ratios.