Hypogonadism can be divided into three forms depending on the cause:
- Primary hypogonadism
- Secondary hypogonadism
- Tertiary hypogonadism
Primary hypogonadism
In primary hypogonadism, the cause lies directly in the gonads. Although the higher-level hormonal centers stimulate the ovaries or testes, these organs produce too few hormones.
A typical congenital primary disorder in men is Klinefelter syndrome. People with this condition have an extra X chromosome instead of the usual XY chromosome set found in men.
Primary hypogonadism also occurs in women with Turner syndrome. Instead of two sex chromosomes (XX), they have only one functional X chromosome.
Similarly, in men, testicular tumors or injuries to the genital area can lead to reduced hormone production. In women, ovarian cancer and/or inflammation in this area can be a possible cause.
Secondary Hypogonadism
Secondary hypogonadism, on the other hand, is caused by a dysfunction of the pituitary gland, which acts as the brain’s central hormonal control center. It secretes follicle-stimulating hormone (FSH) and luteinizing hormone (LH).
These so-called releasing hormones stimulate the gonads to produce sex hormones. Therefore, if there is a deficiency of these releasing hormones, the ovaries and testes produce insufficient amounts of testosterone, estrogen, and progesterone, respectively.
The pituitary gland is an endocrine organ about the size of a hazelnut located in the central nervous system @ bilderzwerg /AdobeStock
A pituitary adenoma is a common condition that can lead to secondary hypogonadism. It is a rare, benign tumor in the head.
Secondary hypogonadism can also develop as a result of congenital disorders, such as Kallmann syndrome, or direct damage to the anterior pituitary lobe.
Tertiary hypogonadism
Tertiary hypogonadism is the rarest form of hypogonadism. It occurs when the cause lies at the level of the hypothalamus.
The hypothalamus is a part of the diencephalon that, like the pituitary gland, releases releasing hormones. However, these hormones do not directly stimulate the gonads; rather, they stimulate the pituitary gland to release FSH and LH.
A deficiency of these pituitary-specific releasing hormones leads to reduced gonadal activity and decreased secretion of sex hormones.
The symptoms are extremely varied and are not limited to the sexual sphere. If there is a lack of testosterone as early as childhood, puberty does not occur.
Doctors also refer to this as eunuchism. Both primary and secondary sexual characteristics fail to develop properly.
Those affected have small testicles and an underdeveloped penis. In addition, body hair is rather sparse. In adulthood, the following symptoms may occur:
- Decreased libido
- Loss of underarm and pubic hair
- Reduced beard growth
- Decreased height
- Spontaneous fractures due to reduced bone density
- Loss of muscle mass and strength
In women, the main symptoms involve irregularities in the menstrual cycle. If the hormonal disorder is present before puberty, affected girls will never get their periods.
Doctors refer to this as primary amenorrhea. Menstruation also fails to occur in adulthood (secondary amenorrhea). Since ovulation does not occur, women with hypogonadism are infertile.
Through a detailed medical history, the treating physician can use specialized questionnaires to identify all symptoms. Often, clues pointing to hypogonadism are already evident at this stage.
A physical examination also reveals findings associated with hypogonadism, such as underdeveloped genitalia or reduced body hair.
However, laboratory tests are essential for establishing a definitive diagnosis.
The doctor measures levels of sex hormones such as:
- testosterone
- Estrogen
- Progesterone
- LH
- FSH
- Sex Hormone-Binding Globulin (SHBG)
If secondary or tertiary hypogonadism is suspected, doctors must also test for organ-specific releasing hormones.
They should always confirm a low hormone level with a second measurement. A temporary decrease may also be caused by other acute illnesses.
If there is a specific suspicion, imaging techniques such as sonography (ultrasound) can also be helpful. These allow the gonads to be visualized and assessed structurally.
A laboratory blood test is necessary for diagnosis @ angellodeco /AdobeStock
Treatment depends on the cause of the hormonal disorder. For example, chemotherapy or radiation therapy is used in cases of tumors.
However, treating the underlying cause is not always possible. To alleviate symptoms, patients are then given hormone preparations in the form of tablets, creams, depot injections, or patches.
Since hormone replacement therapy carries risks, doctors must rule out any potential contraindications before starting treatment.
These include, for example:
- Hormone-dependent tumors
- Hypersensitivity to synthetic hormones or other ingredients in the preparations
- Previous or current liver cancer
The prognosis depends primarily on the underlying cause. If the cause can be effectively treated and patients receive regular sex hormone therapy, secondary sexual characteristics may be restored.
This also helps prevent potential complications caused by the hormone deficiency.
