Hypopituitarism is a clinico-laboratory symptom complex that reflects a decrease in the functional activity of peripheral endocrine glands caused by an imbalance in the process of hormone production by the adenohypophysis.
It is necessary to distinguish such concepts as panhypopituitarism (complete cessation of the production of all hormones in the anterior pituitary gland) and partial hypopituitarism, in which the isolated production of one of the six major hormones of the adenohypophysis is disturbed.
Causes of hypopituitarism
The disease "hypopituitarism" can arise under the influence of a variety of etiological factors, but there are only three main pathogenetic mechanisms of the development of this symptom complex. The degree of impaired productive function of the pituitary gland directly depends on the extent and location of the destructive focus in its structure.
The first etiopathogenetic mechanism consists in reducing the production of hypothalamic hormones, which have a stimulating effect on the production of pituitary hormones. Thus, all pathologies accompanied by functional hypothalamus deficiency inevitably provoke the development of secondary hypopituitarism (tumor, infectious, traumatic damage). Under these conditions, the production of the growth hormone and gonadotropic hormones suffer most.
The second mechanism of pathogenesis is due to insufficient intake of pituitary hormones into the "tropic organs", provided the synthesizing function of the pituitary gland is completely preserved. As a rule, traumatic damage to the hypothalamic-pituitary system plays the most important role in the development of this path of development of hypopituitarism.
The third etiopathogenetic mechanism develops as a result of tumor damage to the pituitary gland at the cellular level, as a result of which most of the glandular tissue of the pituitary is replaced by a tumor substrate, thereby creating conditions for a sharp inhibition of hormone production.
Transient hypopituitarism can be observed after a viral infection in severe form, accompanied by toxic damage to the structures of the brain.
In women who have experienced complicated births , accompanied by thromboembolism and profuse postpartum hemorrhage, postpartum hypopituitarism is often observed.
Among the etiological factors that directly participate in the development of signs of secondary hypopituitarism, it should be considered:
- use of surgical interventions in the hypothalamus and pituitary gland;
- exposure to high doses of ionizing radiation on the pituitary gland;
- tumor lesion of the glandular tissue of the pituitary gland in the form of primary lesion and metastasis;
- Acute circulatory disturbance in the projection of the pituitary gland as a result of loss of a large amount of circulating blood during the period of delivery (the production of thyreotropic and adrenocorticotropic hormones is significantly reduced);
- traumatic effect on the skull region of varying severity (accompanied by dissociation of excessive production of prolactin against a background of a sharp decrease in the production of the remaining hormones of the pituitary gland);
- "empty Turkish saddle" with subsequent increase in the production of prolactin;
- pituitary diseases, accompanied by massive infiltrative changes;
- disorders of the hypothalamic-pituitary system of a functional type in the syndrome of malabsorption, severe diabetes mellitus , anorexia of the neurogenic nature , renal insufficiency (accompanied by ischemic necrosis of the anterior lobe of the pituitary gland). This decrease in the level of tropic hormones is a reversible process and in order to completely recover the patient, in some cases it is only necessary to carry out etiotropic therapy;
- physiological dysfunction of the hypothalamic-pituitary system during puberty and with excessive physical activity of young people (the level of estradiol in the blood is lowered);
- prolonged use of narcotic drugs is accompanied by a violation of the secretion of testosterone;
- Hyperprolactinemia , as an inhibitory factor in the development of hypopituitarism.
There are also congenital types of hypopituitarism caused by genetic aberrations and anomalies in the development of the structures of the hypothalamic-pituitary system. These predisposing factors provoke the development of signs of hypopituitarism immediately after the birth of the child. Fortunately, hypopituitarism in children is extremely rare.
In a situation where it is not possible to reliably establish the primary or secondary nature of the pituitary lesion, the conclusion is "idiopathic hypopituitarism".
Symptoms of hypopituitarism
The most important fact is that a typical clinical symptom complex of hypopituitarism is formed only when the percentage of normally functioning pituitary cells does not exceed 10%, therefore, this pathology should be classified as a slow-progressive disease.
In a situation where gonadotropin production suffers, the diagnosis of hypopituitarism does not cause difficulties for an experienced clinician. If these changes are of an innate nature, then the child from an early age can have signs of hypopituitarism, which consist in lagging behind the age of the bone age, the formation of the eunuchoid type of build, and in adolescence, there is a significant lag in sexual development.
Secondary hypopituitarism, accompanied by a disruption in the production of gonadotropins in the adult period, is reflected in the form of a sudden and progressive decrease in potency, the erasing of secondary phenotypic traits (a decrease to the complete absence of hair in the projection of the axillae and pubis, a decrease in the size of the scrotum, diffuse atrophy of muscle tissue in the body followed by its replacement by fat). Women of reproductive age with signs of hypopituitarism complain about a decrease in sexual desire, dysmenorrhea, the appearance of pain during sexual intercourse due to thinning of the tissues of the external genitalia.
The specific and most common symptom of hypopituitarism of any form is the violation of the olfactory function of varying severity.
With an isolated impairment of the production of growth hormone by the pituitary gland, the adult has a pronounced muscular weakness even after minimal physical activity, accompanied by disturbances in the rhythm of the cardiac activity. In the children's period, these disorders are reflected in the lag in the formation of the skeleton.
Imbalance in the production of thyroid-stimulating hormones in the early childhood significantly affects the mental and physical development of the child, and in young and mature patients these changes are manifested by the symptomatic complex of hypothyroidism (unmotivated weakness, propensity to bradycardia and hypotension , disruption of intestinal function).
Hypopituitarism caused by tumor damage to the pituitary gland is marked by a marked violation of the patient's neurological status in the form of a permanent headache that does not have a clear localization, a violation of the visual function, various degrees of impaired consciousness.
Diagnosis of hypopituitarism
Despite the fact that the severity and specificity of the clinical manifestations of both primary and secondary hypopituitarism, it is not difficult to determine the diagnosis, this pathology belongs to the category of laboratory disorders, therefore, each specific clinical case must be confirmed laboratory and instrumental.
Diagnose the tumor lesion even the smallest size allows the currently available radiation imaging methods. When carrying out radiation diagnosis, it is necessary to evaluate the parameters of the tumor substrate, its location relative to the bone structures of the pituitary fossa and the presence of signs of malignancy.
In the list of the diagnostic algorithm for the research of puerperas with suspicion of having postpartum hypopituitarism, the following measures must necessarily be present: Estimation of estrogenic activity of the ovaries for the study of the smear reaction from the vagina, determination of serum levels of thyroid-stimulating hormones, and indirect signs of anemia in blood test.
The most informative in terms of determining the degree of impairment of the production function of the pituitary gland are laboratory tests of blood with the determination of the concentration of certain gonadotropic hormones in the blood serum both on an empty stomach and after using stimulating pharmacological samples.
So, there are common diagnostic criteria for the insufficiency of a hormone of the pituitary gland. For example, in order to establish gonadotropin deficiency in males, it is sufficient to determine a low level of testosterone below the 200 ng / dL limit. In order to reliably determine the concentration of corticotropin in the blood, it is not enough to perform an analysis on an empty stomach, but it is necessary to perform a stimulating test with Cosintropin in a standard dosage of 250 μg. A corticotropin index of less than 18 μg / dL after the sample is an absolute criterion for hypopituitarism.
A distinctive feature of the diagnosis of patients with hypopituitarism with suspicion of an isolated deficit of growth hormone is its mandatory determination not only in the blood, but also in the urine. And in childhood, it is necessary to perform X-ray of the hands and pelvis for the purpose of determining the bone age.
Treatment of hypopituitarism
To achieve good results of treatment of patients with hypopituitarism in the form of complete recovery and prevention of possible complications of the underlying disease, the initial stage of therapy should be the determination of etiopathogenesis and pharmacological effect on all links of the pathogenesis of the disease.
In a situation where hypopituitarism acts as a consequence of tumor damage to the hypothalamus or pituitary gland, it is first necessary to decide on the appropriateness and acceptability of surgical intervention and subsequent radiotherapy.
The next stage in the treatment of hypopituitarism is the use of adequate "substitution therapy" with the use of drugs, the active ingredient of which is a hormone, the development of which suffers. For example, the gold standard for the treatment of corticotropin deficiency is a substitution therapy with Cortisol, whose daily dose is at least 10 mg with the morning intake of the drug. The pronounced insufficiency of gonadotropins is leveled after prolonged use of testosterone preparations (Sustanon 1 ml 1 r./month intramuscularly). After laboratory confirmation of the failure of thyroid-stimulating hormones, it is advisable for a patient to prescribe L-thyroxin in a minimum daily dosage of 0.1 mg in combination with the use of corticosteroids (Prednisolone 25 mg) in order to prevent the appearance of signs of adrenal insufficiency.
In the case of acute hypopituitarism, provoked by a hemorrhage into the pituitary gland, the patient is in extremely serious condition and needs urgent emergency resuscitation. As first aid drugs in this situation, intravenous infusion of Hydrocortisone in a dose of 100 mg in combination with parenteral administration of saline solutions.
A special feature of the treatment of the postpartum type of hypopituitarism is the replacement therapy for life, since the pathogenesis of this pathology is based on irreversible processes in the pituitary gland.