Androgens in Health and Disease.pdf - E Library

Chapter 22/Androgens in Primary Care 425
Fig. 1. (E) Dysfunction of Sertoli cells leads to abnormal spermatogenesis, decreased inhibin B
secretion, and isolated elevation of circulating FSH and LH levels.
Table 3
Common Causes of Primary Hypogonadism
Prepubertal onset (small testes)
Klinefelter’s syndrome (XXY males)
Postpubertal onset (normal testes)
Mumps orchitis (usually does not cause hypogonadism if prepubertal)
Autoimmune orchitis
Trauma
Testicular irradiation or surgery
Summary of the Evaluation of Gonadal Axis
When male hypogonadism is being considered, clinicians should order a serum total
testosterone (or calculated free and bioavailable testosterone when this assay has been
validated in the primary care setting) plus serum LH and FSH levels (Fig. 2). If the patient
has primary hypogonadism with low serum testosterone plus elevated gonadotropins, no
further work-up is necessary. If the patient has a pattern suggesting secondary hypogonadism
(low serum testosterone plus low or normal gonadotropins), the laboratory assessment
should be repeated. Any acute systemic illness may suppress the gonadal axis and
cause a biochemical profile identical to secondary hypogonadism. Thus, it would be best
to repeat the gonadal assessment when the man has been healthy for some period of time.