Tuesday, April 12th, 2011 at
7:24 pm
So just how does the male body produce testosterone? While the number of systems that can impact testosterone production is large in number, the basics are rather simple. Let’s start at the hypothalamus and work our way down.
- The hypothalamus produces gonadotropin-releasing hormone (GnRH)
- This hormone triggers the anterior pituitary gland to produce two other hormones
- These two hormones are luteinizing hormone (LH) and follicle-stimulating hormone (FSH)
- LH stimulates the Leydig cells in the testicles to produce testosterone while FSH regulates the development, growth, pubertal maturation, and reproductive processes of the body and acts synergistically with LH in male reproductive health.
Simple enough, but what happens is one or more of these systems is compromised in some manner? Defects in the hypothalamus or pituitary gland that compromise the release of GnRH (and subsequently FSH and LH) or adversely affect the release of FSH or LH from the anterior pituitary lead to what is known as secondary hypogonadism. A defect in the testicles that causes a reduction or cessation of gonadal response to LH is characterized as primary hypogonadism. There are many causes of both primary and secondary hypogonadism. The link lists only some of the causes. Also check out this link. Hypogonadism that is present absent any of these conditions or any other known conditions that affect male testosterone production comes under the heading idiopathic hypogonadism. This later label correctly describes my own condition.
Typically a doctor will order a test that measures the total serum testosterone. This is a simple blood test that provides a number, usually in the units of nanograms per deciliter (ng/dl). Normal values vary by the lab performing the test on the blood sample, but typically values are from around 300ng/dL to 1000ng/dl. However, caution should be used in using this raw value as an stark indicator of hypogonadism. For some men presenting with low normal values or even normal values symptoms of low testosterone are often seen. Therefore the entire clinical picture is needed to ensure treatment is provided even in the face of so-called normal results. Also, an entire workup of the thyroid function as well as adrenal function is necessary. Any issue with either of these glands can often lead to hypogonadism or mimic they symptoms of hypogonadism. Also, an understanding of any issues with these glands will guide the treating physician in the selected treatment. As an example, long-standing hypothyroidism will impair the absorption of transdermal testosterone due to build-up of mucin in the skin of people. Mucin causes the skin to thicken impairing absorption of transdermal testosterone.
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