Clinical evaluation of serum testosterone, along with serum LH, assists in evaluation of hypogonadal males. Major causes of lowered testosterone in males include hypogonadotropic hypogonadism, testicular failure, hyperprolactinemia, hypopituitarism, some types of liver and kidney diseases, and critical illness. Increased serum testosterone levels in females may be indicative of polycystic ovary syndrome and adrenal hyperplasia, among other contitions. The clinical manifestations of excess testosterone include infertility, hirsutism, amenorrhea and obesity.