Hypopituitarism is a decrease in hormonal secretions from the anterior lobe of the pituitary gland. It can be caused by disorders that affect the pituitary gland or by dysfunction of the hypothalamus, the nerve center that controls the pituitary gland.

The symptoms appear gradually and depend on the deficient hormones. Treatment targets the cause of pituitary hypoactivity, especially in the case of a tumor. At the same time, it consists of replacing the missing hormones with drugs.

Definition

Hypopituitarism is a decrease in hormonal secretions from the anterior lobe of the pituitary gland, the endocrine gland located at the base of the skull.

The hormones secreted by this part of the pituitary gland are as follows:

Pituitary stimulins

They are secreted under the control of hypothalamic factors, and they stimulate their other endocrine glands (adrenals, thyroid, ovaries, testes, etc.)

• Thyroid stimulating hormone (TSH) stimulates the secretion of thyroid hormones
• Corticosteroids (ACTH) controls adrenal secretions (cortisol and androgens)
• Gonadostimulins: follicle-stimulating hormone (FSH) acts on ovarian development and spermatogenesis; Luteinostimulin (LH) is secreted at the time of ovulation, and in men it stimulates the secretion of testosterone.
• Prolactin stimulates lactation and controls the production of progesterone

Growth hormone (STH)

It acts on growth and the various metabolisms (carbohydrates, lipids, proteins) by stimulating them.

Types

This deficit can affect all the secretions of the anterior lobe of the pituitary gland (panhypopituitarism) or only concern certain secretions (dissociated hypopituitarism).

Hypopituitarism is:

• Primary when caused by disorders that affect the pituitary gland
• Secondary when caused by dysfunctions of the hypothalamus, the nerve center that controls the pituitary gland

Causes

Most hypopituitarisms are acquired.

Primary hypopituitarism can be caused by:

• Pituitary gland tumor
• Ischemic infarction or necrosis (death of tissue due to decreased blood supply) of the pituitary gland. Sheehan’s syndrome is necrosis of the anterior lobe of the pituitary gland that occurs after a difficult delivery.
• Inflammatory processes such as meningitis, pituitary abscess or sarcoidosis.

Infiltrating diseases such as hemochromatosis (overload of iron in the body) or Langerhans cell histiocytosis (a condition in which cells called histiocytes multiply in the pituitary gland)

• Iatrogenic causes: irradiation or removal of the pituitary gland, inflammation of the pituitary gland following the intake of monoclonal antimelanoma antibodies
• Autoimmune diseases, in particular lymphocytic hypophysitis.

Secondary hypopituitarism can be caused by:

• Hypothalamus tumors
• Inflammatory processes such as sarcoidosis
• Neurohormonal deficiency of the hypothalamus
• Iatrogenic causes, including surgical section of the pituitary stem (the anatomical structure that connects the pituitary gland to the hypothalamus)
• Trauma: fracture of the base of the skull

Diagnostic

First, the diagnosis is based on blood tests. Since the pituitary gland stimulates other glands, a deficiency of pituitary hormones often results in a decrease in the amount of hormones produced by these other glands. Doctors must therefore suspect pituitary insufficiency in the face of dysfunction in another gland such as the thyroid or the adrenal gland.

The assessment usually begins with measuring the blood levels of hormones produced by the pituitary gland. At the same time, the levels of the hormone produced by the target organs (thyroid, testosterone in men and estrogen in women) are measured.

Hypopituitarism affects men and women of all ages. Symptoms differ from sex to sex, and depending on age.

Symptoms appear gradually, and they depend on which hormones are in deficit.

Growth hormone deficiency (STH)

In children, growth hormone deficiency typically results in overall growth retardation and short stature. Adults sometimes show a lack of energy.

Deficiency of gonadotropins (follicle stimulating hormone and luteinizing hormone)

In premenopausal women, the deficiency of these hormones leads to stopping menstrual cycles, infertility, vaginal dryness and the loss of certain female sexual characteristics.

In men, it causes a decrease in the size of the testes, a decrease in sperm production, erectile dysfunction and the loss of certain male sex characteristics.

In children, the deficiency of these hormones results in delayed puberty.

Thyroid stimulating hormone (TSH) deficiency

Thyroid stimulating hormone deficiency causes insufficient thyroid activity which leads to confusion, intolerance to cold, weight gain, constipation and dry skin.

Adrenocorticotropic hormone deficiency

Corticosteroid-stimulating hormone (ACTH) deficiency causes adrenal insufficiency which manifests as severe fatigue, hypotension, low blood sugar and poor tolerance to stress. The complete lack of production of ACTH by the body can be fatal.

Prolactin deficiency

Prolactin deficiency causes women to have reduced or no milk production after childbirth.

If the cause of hypopituitarism is a tumor, other symptoms may appear:

• Tumors that affect the hypothalamus can cause pituitary hormone deficiencies, and disrupt the centers that control appetite resulting in obesity.
• Tumors that affect the pituitary gland can cause severe headache, stiff neck, fever, visual field changes, and eye movement disturbances.

Treatment targets the cause of pituitary hypoactivity, especially in the case of a tumor. At the same time, it consists of replacing the missing hormones with drugs. Growth hormone is the only pituitary hormone that is substituted. It must be administered by injection. In other cases, it is not the pituitary hormones that are replaced but their target hormones.

• TSH deficiency: administration of thyroxine
• ACTH deficiency: administration of hydrocortisone
• Gonadotropin deficiency: administration of estrogen, progesterone or testosterone

The appearance of an isolated pituitary deficit may precede the development of generalized hypopituitarism. Patients should be monitored for signs of pituitary hormone deficits, and pituitary imaging should be performed regularly to check for the appearance of pituitary tumor.