Secondary hypothyroidism, its diagnosis and treatment
The concept of diagnosis of secondary hypothyroidism is impossible without explaining the relationship between individual organs of internal secretion in the endocrine system. The hypothalamus and pituitary gland are regulators of the thyroid gland functioning, which is carried out with the help of two kinds of hormones - thyreotropic hormone( TSH) and thyrotropin-stimulating hormone( TRH).All three glands form a single chain, which regulates the work of the entire human body.
Why does secondary hypothyroidism occur?
The hypothalamus controls the pituitary gland by means of thyrotropin-releasing hormone( TRH), and the pituitary gland, in turn, regulates the thyroid gland with the help of thyroid-stimulating hormone. With a lack of hormones T3 and T4, produced by the thyroid gland, the level of thyrotropic hormone immediately increases and, conversely, when they increase, the secretion of TSH by the pituitary gland decreases.
When hypothyroidism occurs in the thyroid gland, there is a decrease in the production of hormones, but the main reason lies in the disruption of the connections between the hypothalamus, pituitary and thyroid gland. That is, in other words speaking, the thyroid gland itself and its diseases are not the causes of the appearance of secondary hypothyroidism.
Causes that may cause a disruption to this connection are as follows:
- Brain trauma( including pituitary gland or hypothalamus).
- Hemorrhage in the brain, the area of which extends to the hypothalamic-pituitary zone.
- Viral, fungal or bacterial involvement of the hypothalamus or pituitary gland. Benign or malignant neoplasms of the brain.
- Disturbance of cerebral circulation.
- Pathology of the adrenal cortex.
- Abnormalities of the brain.
- Massive blood loss, causing necrosis of individual pituitary glands.
- Radiation therapy or chemotherapy after oncological diseases.
Symptoms of a disease
When diagnosed as a secondary hypothyroidism, the symptoms in many cases are similar to the symptoms of primary hypothyroidism, but unlike it, the symptoms appear one after another, causing gradually the entire clinical picture. This is because even with disruption of the connections between the individual glands of internal secretion, the thyroid gland, remaining without proper regulation, continues to produce other hormones.
Since the hypothalamus and pituitary gland secrete many other hormones that control the work of other organs, secondary hypothyroidism shows signs of pathology from the lungs, heart, kidneys and other organs.
So, the symptoms of secondary hypothyroidism are:Pale and dry skin.
Diagnosis and treatment of secondary hypothyroidism
To diagnose, conduct the following methods of examination and diagnosis:
- Ultrasound examination of the thyroid gland. Isotope scintigraphy of the gland.
- Thyroid tissue biopsy.
- Blood test for the level of TTG, TRH and thyroid hormones.
- CT and MRI of the brain.
With the disease "secondary hypothyroidism," the treatment is reduced, first of all, to the detection and treatment of the underlying cause that caused the disruption of the endocrine glands. The brain tumors are removed, the consequences of trauma or hemorrhage are treated, foci of infection are eliminated and so on.
If necessary, substitution therapy is administered, during which the patient takes lifelong synthetic analogues of thyroid hormones( L-thyroxine), which with regular admission can eliminate a large number of symptoms of the disease.