Types of Hypogonadism in Testosterone Deficiency

There are different reasons that will cause a man to be deficient in testosterone. They are classified into three categories. First, we need to understand some basic anatomy and how the body functions, more specifically, the Hypothalmic Pituitary Gonadal (HPG) Axis.

The hypothalmus is located in the brain and sends Gonadotropin-Releasing Hormone (GnRH) to the anterior pituitary gland and tells it to secrete gonadotropins which are, Luteinizing Hormone (LH) and Follicle Stimulating Hormone (FSH).

• LH: Gets sent to the Leydig cells in the testes to produce testosterone. Testosterone then gets sent out in to the body for use.

• FSH: Gets sent to the Sertoli cells in the testes to produce sperm.

When the testes have produced enough testosterone, it will inhibit LH and FSH production in the feedback loop as shown in the image below. When the body needs more testosterone, the HPG Axis will activate again and go through the process of testosterone and sperm production all over again as mentioned above. This process is ongoing.

HPG Axis

There are 3 types of hypogonadism:

1. Primary Hypogonadism (most common): This occurs when FSH and/or LH will be normal or elevated on lab work because the failure is at the testes in the feedback loop of the HPG Axis. So, FSH & LH crank out from the pituitary gland as normal, but the testes are not responding. Causes of this include testicular malfunction, genetic disorders such as Klinefelter Syndrome, testicular cancer or trauma, undescended testicles, and hypothyroidism (low thyroid function).

2. Secondary Hypogonadism: This occurs when FSH and/or LH will be diminished because the failure is at the pituitary gland level. The testes never receive the signal of FSH and LH from the pituitary gland. Causes of this include pituitary adenoma, when the patient is already on testosterone replacement therapy, genetic disorders such as Kallmann Syndrome, certain medications and opiates, obesity, and hypothyroidism (low thyroid function).

3. Tertiary Hypogonadism: This occurs when the hypothalmus does not produce GnRH because the failure occurs at the hypothalmus in the HPG Axis. When failure occurs here, so does the rest of the HPG Axis as a result of a "domino effect." Causes of this is typically due to a head injury.

Signs and symptoms are the same across all of the different types of hypogonadism mentioned above. How it is determined is through blood work and other testing. Signs and symptoms include:

• Low libido

• Decreased energy

• Depression

• Erectile Dysfunction

• Infertility

• Decreased growth of hair on face and body

• Decrease in muscle mass

• Decrease in bone mass

• Increased body fat

• Difficulty concentrating

Treatment for all three types of hypogonadism is Testosterone Replacement Therapy (TRT)! We replace what your body cannot make!