luteinizing hormone (LH) and follicle-stimulating hormone (FSH) assay, a blood test used in the evaluation of infertility. An LH assay is an easy way to determine if ovulation has occurred. The LH assay and FSH test also are used to determine whether a gonadal insufficiency is primary (a problem with the ovary or testicle) or secondary (caused by pituitary insufficiency resulting in reduced levels of FSH and LH).
