Compatible cut‐off values for luteinizing hormone and the luteinizing hormone/follicle‐stimulating hormone ratio in diagnostic criteria of the Japan Society of Obstetrics and Gynecology for polycystic ovary syndrome

Aim The abnormal secretion of luteinizing hormone (LH) is one of the typical features of polycystic ovary syndrome (PCOS) and adopted in the diagnostic criteria of the Japan Society of Obstetrics and Gynecology (JSOG). We investigated cut‐off values for LH and the LH/follicle‐stimulating hormone (FSH) ratio in resent two measurement systems for the diagnosis of PCOS. Methods Ninety‐nine controls and 106 patients with PCOS were enrolled. Serum LH and FSH levels were measured using an electrochemiluminescence immunoassay (ARCHITECT) and chemiluminescence immunoassay (ECLusys). We examined the distribution of the measured levels, selected the conversion closest to the standard normal distribution in the control group, and calculated mean + 1 SD values for LH and the LH/FSH ratio as candidates. Cut‐off values coincided with the medians of the candidates in the two assay systems using a regression equation. We calculated the endocrinological abnormality rate in PCOS according to the JSOG criteria by abnormal LH secretion and elevated T. Results Cut‐off values for LH (mIU/mL) and the LH/FSH ratio were 7.1 and 1.21, respectively, in ARCHITECT, and 9.9 and 1.51, respectively, in ECLusys. The detection rates of endocrinological abnormalities in PCOS were 72.2% and 70.6% in the nonoverweight/obese PCOS group and overweight/obese PCOS group, respectively, in ARCHITECT, and 69.4% and 73.5%, respectively, in ECLusys. Conclusion We obtained cut‐off values of LH and the LH/FSH ratio for diagnostic criteria of JSOG criteria for PCOS, that were highly compatible between two major assay systems. These cut‐off values will contribute to the diagnosis of PCOS in Japan and presumably in women of Asian ethnicities.