Panhypopituitarism - classification, etiology, pathogenesis, and clinical manifestations
Panhypopituitarism is a deficiency of all anterior pituitary hormones, leading to multiple endocrine gland failures.
Classification
- 1 According to onset
- 2 According to extent
Etiology
Pituitary causes (primary)
Tumors:
- Non- functioning pituitary adenoma (most common).
- Craniopharyngioma.
- Metastatic tumors.
Infarction/ischemia:
- Sheehan syndrome (postpartum pituitary necrosis due to severe blood loss).
- Pituitary apoplexy (sudden hemorrhage into a tumor ).
Infections/inflammation:
- Tuberculosis, sarcoidosis.
- Hypophysitis (autoimmune or lymphocytic).
Radiation therapy or surgery.
Hypothalamic causes (secondary)
Tumors (e.g., gliomas).
Infiltrative diseases (sarcoidosis, histiocytosis).
Trauma.
Pathogenesis
- 1 Destruction or compression of anterior pituitary cells → hormone production
stops.
- 2 Failure to stimulate peripheral endocrine glands → secondary deficiencies of:
- Cortisol (via ACTH).
- Thyroid hormones (via TSH).
- Sex steroids (via LH, FSH).
- IGF- 1 (via GH).
- Prolactin usually decreased, but sometimes normal or increased depending on stalk effect.
- 3 Leads to multiple endocrine failures, affecting metabolism, reproduction, and growth.
Clinical manifestations
General symptoms
- Fatigue, weakness.
- Weight loss.
Due to ACTH deficiency
- Secondary adrenal insufficiency:
- Hypotension.
- Hypoglycemia.
- Weakness, nausea.
Due to TSH deficiency
- Secondary hypothyroidism:
- Cold intolerance.
- Bradycardia.
- Dry skin, hair loss.
- Constipation.
Due to LH and FSH deficiency
- In women:
- Amenorrhea or oligomenorrhea.
- Infertility.
- Decreased libido.
- Breast atrophy.
- In men:
- Decreased libido.
- Erectile dysfunction.
- Testicular atrophy.
- Decreased facial and body hair.
Due to GH deficiency
- In children:
- Growth retardation (pituitary dwarfism).
- In adults:
- Decreased muscle mass and strength.
- Increased fat mass.
- Osteoporosis.
- Reduced quality of life.
Due to prolactin deficiency
- Failure of lactation after delivery.
Possible visual symptoms
- From tumor mass effect (e.g., bitemporal hemianopia due to optic chiasm compression).