Characteristics and basic classification
In clinical pathophysiology, all nosological forms of adenohypophyseal pathology are conventionally classified according to several strict criteria. Regardless of the patient's age (pathologies occur in both children and adults), all diseases of this localization are broadly divided into two large groups depending on the functional state of the gland:
- Hyperpituitary forms — conditions characterized by an excess of anterior pituitary function and excessive production of the corresponding hormones.
- Hypopituitary forms — pathologies based on adenohypophyseal insufficiency.
Hypopituitarism: definition and types
Hypopituitarism is defined as a standard form of adenohypophyseal pathology, the essence of which is the deficiency and/or decreased physiological effects of one or more of its hormones simultaneously.
Depending on the extent of functional loss, the main types of adenohypophyseal insufficiency are combined into two key groups:
- Partial disorders.
- Total disorders (panhypopituitarism).
Partial forms
This group of pathologies is characterized by the loss of function of individual adenohypophyseal hormones. The main nosologies of partial hypopituitarism include:
- Pituitary hypogonadism (decreased function related to the regulation of the gonads).
- Pituitary obesity.
- Pituitary dwarfism, also known in medical terminology as nanism.
- Adiposogenital dystrophy.
- Pituitary hypocortisolism, which is classified as secondary adrenal insufficiency.
- Pituitary hypothyroidism (secondary hypothyroidism).
Total forms (panhypopituitarism)
Unlike partial disorders, total forms are characterized by the complete (total) loss of all adenohypophyseal functions. This severe group of pathologies includes:
- Pituitary cachexia (often referred to in clinical practice as Simmonds' disease).
- Postpartum hypopituitarism (Sheehan's syndrome).
- General hypothalamic-pituitary insufficiency.
Clinical features
A most important rule of endocrinology and pathophysiology states: “pure” partial isolated forms of adenohypophyseal insufficiency are practically non-existent in practice.
As a rule, a patient develops a combined deficiency of several hormones simultaneously. Nevertheless, the symptoms are always dominated by the signs of deficiency of a single tropic function. It is this leading syndrome that will determine the entire clinical presentation of the disease encountered by the physician.
Briefly: answers to topical questions
What are the main causes of Sheehan's syndrome development?
The main causes of Sheehan's syndrome are massive postpartum or post-abortion hemorrhages. The hemorrhage leads to acute infarction or necrosis of the pituitary gland, as well as intravascular thrombosis. Ischemia is additionally promoted by the physiological postpartum decrease in ACTH secretion.
Which specific hormones does the adenohypophysis produce?
The adenohypophysis produces the following hormones:
- Follicle-stimulating hormone (FSH).
- Luteinizing hormone (LH).
- Adrenocorticotropic hormone (ACTH, corticotropin).
- Growth hormone (GH / somatotropic hormone).
- Thyroid-stimulating hormone (TSH, thyrotropin).
- Prolactin (lactogenic, lactotropic hormone).
- Melanocyte-stimulating hormone.
What is the difference between Cushing's disease and Cushing's syndrome?
The difference between Cushing's disease and Cushing's syndrome lies in the localization of the primary lesion and the ACTH level.
| Sign | Cushing's disease | Cushing's Syndrome |
|---|---|---|
| Genesis | Central (pituitary adenoma) | Peripheral (adrenal tumor or hyperplasia, ectopic ACTH production) |
| ACTH level | High | Low (via negative feedback mechanism) |
| Pathogenesis | Pituitary adenoma hypersecretes ACTH, which secondary hyperstimulates the adrenal cortex | Autonomous hormone hypersecretion by the primary lesion in the adrenals themselves |
To memorize total forms of hypopituitarism, use the mnemonic SSH: Simmonds (cachexia), Sheehan (postpartum), Hypothalamic-pituitary insufficiency.
Class and exam questions
What determines the clinical picture in combined adenohypophyseal lesions?
In combined deficiency, the clinical picture is determined by the leading syndrome—the dominant signs of deficiency in any single tropic function.
Are there any absolutely pure partial forms?
No, pure isolated partial forms of adenohypophyseal insufficiency are practically non-existent. Combined deficiency is most commonly observed.
What are the alternative names for hypophyseal hypothyroidism and hypocorticism?
Pituitary hypothyroidism is called secondary hypothyroidism, and pituitary hypocorticism is called secondary adrenal insufficiency.
What else to study on this topic
- Mechanisms and causes of hyperpituitary states
- Pathogenesis of Simmonds' disease (pituitary cachexia)
- Etiology of Sheehan's syndrome in the postpartum period
- Clinical manifestations of adiposogenital dystrophy
- Features of diagnosing secondary adrenal insufficiency
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