Which bodily substance is primarily tested to measure 17-ketosteroids?

The measurement of 17-ketosteroids is primarily performed using urine samples. This is because 17-ketosteroids are metabolites of adrenal hormones, specifically androgens and corticosteroids, and are excreted in the urine. Urine testing allows for a comprehensive assessment of these metabolites over a period of time, giving a better indication of adrenal function and steroid production.

Blood samples, while useful for some hormone testing, do not provide as comprehensive a view of the excretion of 17-ketosteroids as urine does. Saliva may be used for some hormone assessments but is not the standard for measuring 17-ketosteroids due to lower concentrations and variability. Sweat is not typically evaluated for this purpose, as it is not a reliable source for measuring steroid metabolites. Therefore, urine is the preferred and most effective medium for assessing 17-ketosteroids in clinical practice.