What is the Origin of Serum Testosterone Concentration?

The measurement of circulating hormones has been a cornerstone of clinical endocrinology since the development of radioimmunoassay (RIA) techniques in the mid-20th century. The term 'serum' specifies the liquid component of blood after clotting, and 'concentration' denotes the measured quantity per volume. This measurement provides an objective, quantitative assessment of the body's androgenic status.

What is the Mechanism of Serum Testosterone Concentration?

Testosterone is primarily synthesized from cholesterol in the Leydig cells of the testes and the theca cells of the ovaries, with minor contributions from the adrenal glands, regulated by the hypothalamic-pituitary-gonadal (HPG) axis. The serum concentration reflects the balance between hormone production, metabolic clearance by the liver, and binding to transport proteins like Sex Hormone Binding Globulin (SHBG). Accurate measurement of this concentration is the initial step in assessing a patient's hormonal homeostasis.

Serum Testosterone Concentration

Meaning

Serum testosterone concentration is the quantitative measurement of the total amount of testosterone hormone present in a milliliter of blood serum, typically expressed in nanograms per deciliter (ng/dL) or nanomoles per liter (nmol/L). This clinical biomarker is fundamental in endocrinology, reflecting the gonadal and adrenal production of the primary male androgen and a critical hormone for women’s metabolic and bone health. Its value is essential for diagnosing conditions like hypogonadism and polycystic ovary syndrome (PCOS).