Diagnosis and evaluation of hypogonadism.

[kallmann syndrome]

Hypogonadism is defined as defects in gonadal response to gonadotropins or sex hormone biosynthesis . Clinical evaluation and diagnosis of patients is challenging , particularly before puberty . Basal determinations of the gonadotropins luteinizing hormone , follicle-stimulating hormone , the gonadal sex steroids testosterone and /or estrogen and markers of gonadal function including inhibin B and anti-Müllerian hormone are useful , but only at specific ages , thus necessitating combined hormonal tests with meticulous physical examination . GnRH testing can be useful , and may be used in combination with hCG testing to discriminate between isolated hypogonadotropic hypogonadism and constitutional delay of growth and puberty . Urine steroid profiles may be helpful in the diagnosis of androgen biosynthetic defects . Also increasingly important is genotypic screening for genetic or chromosomal abnormalities , together with detailed family and medical histories including antecedent substance abuse , chronic disease , and exposure to chemotherapy or radiotherapy . This chapter explores the diagnosis and evaluation of patients with hypogonadism and reviews the genetic /chromosomal factors involved in the condition .