Hypo-Gonadism Disorder: Case Study

A nine-year-old boy is brought into a clinic suspected of having a hypo- gonadism disorder. The physician ordered a test of the boys free testosterone after having considered this was the best option compared to testing the total testosterone. The test results came back at 25.0pg/ml reference range 0.1-3.2pg/ml flagged as high for the boy. Several months later a repeated test showed 28.0pg/ml reference range of 50-210pg/ml adult reference range flagged as high. Our paper will go into detail of how testosterone is tested, and relate it to the boy in figuring out what condition he may have.

Testosterone is the main sex hormone in males, and only a small fractioncirculates the blood in a free state. Most testosterone circulates bound to two proteins, sex hormone binding protein (SHBG), and albumin. Total testosterone levels are a combination or SHBG-bound, albumin-bound, and free testosterone. The bioavaible form (form that can bind to receptors) of testosterone includes that bound to albumin and the free fraction. On average albumin holds 54%, SHGB 44% and free 2% so it appears that 56% of testosterone is in the bioavaible state (2).

So with this in mind our first situation concerns SHGB concentrations, which can be influenced by a variety of factors. SHGB concentrations can become decreased by obesity and testosterone treatments, while also becoming increased in aging (5). With almost half of the testosterone bound by SHGB, and with these common conditions in play, its possibly to see how these factors could influence the free testosterone levels. In such circumstances a test of total testosterone may be warranted in the clinical decision-making of this patient.

Free testosterone has been estimated from the serum for some time by dialyzing serum across a semipermeable membrane with the testosterone that crosses in the serum believed to be the unbound portion or free. Most dialysis assays use small tracer amounts of radiolabeled testosterone added to the serum.