Hypopituitarism
A complex syndrome marked by metabolic dysfunction, sexual immaturity, and growth retardation (when it occurs in childhood), hypopituitarism results from a deficiency of the hormones secreted by the anterior pituitary gland. The disorder is also known as panhypopituitarism and dwarfism.
Panhypopituitarism refers to a generalized condition caused by partial or complete failure of the gland to produce all six of the vital hormones: corticotropin, thyroid–stimulating hormone (TSH), luteinizing hormone (LH), follicle–stimulating hormone (FSH), growth hormone (GH), and prolactin. Partial hypopituitarism and complete hypopituitarism occur in adults and children.
Pediatric pointerIn children, partial hypopituitarism and complete hypopituitarism may cause dwarfism and pubertal delay.
Total loss of all hormones is fatal unless treated, but the prognosis is good with adequate replacement therapy and correction of the underlying causes.
Causes
The most common cause of primary hypopituitarism is a tumor. Other causes include congenital defects (hypoplasia or aplasia of the pituitary gland); pituitary infarction (most commonly from postpartum hemorrhage); partial or total hypophysectomy by surgery, irradiation, or chemical agents; and, rarely, granulomatous disease such as tuberculosis. Occasionally, primary hypopituitarism has no identifiable cause.
Secondary hypopituitarism stems from a deficiency of releasing hormones produced by the hypothalamus. The process may be idiopathic or may result from infection, trauma, or tumor.
Complications
Any combination of deficits in the production of the six major hormones may occur. If the process is an evolving one (due to a hypothalamic destructive lesion), additional hormonal deficiencies may occur over time. Hypopituitarism can result in GH deficiency, TSH or corticotropin deficiency, and gonadotropin and prolactin deficiency. Pituitary apoplexy is a medical emergency. (See Identifying pituitary apoplexy.) The patient’s inability to cope with minor stressors can lead to high fever, shock, coma, and death. In secondary hypopituitarism, damage to the posterior pituitary from infection, trauma, or tumor is occasionally extensive enough to cause diabetes insipidus.
Assessment
Physical findings depend on the specific pituitary hormones that are deficient, the patient’s age, and the disorder’s severity. Typically, clinical features develop slowly and don’t become apparent until 75% of the pituitary gland is destroyed. Assessment findings related to specific hormonal deficiencies include the following:
GH deficiency. Physical signs of GH deficiency may not be apparent in neonates, but by age 6 months, growth retardation is obvious. In children, inspection reveals chubbiness from fat deposits in the lower trunk, short stature, delayed secondary tooth eruption, and delayed puberty. Growth continues at less than half the normal rate—sometimes extending into the patient’s 20s or 30s—to an average height of 4″ (1.2 m), with normal proportions.
Inspection of adults with GH deficiency finds more subtle signs such as fine wrinkles near the mouth and eyes.
Gonadotropin (FSH and LH) deficiency. In females, history discloses amenorrhea; dyspareunia related to reduced vaginal secretions; infertility; and reduced libido. Inspection may reveal breast atrophy, sparse or absent axillary and pubic hair, and dry skin. Males report weakness, impotence, and reduced libido. Inspection may show decreased muscle strength, testicular softening and shrinkage, and retarded secondary sexual hair growth.
TSH deficiency. Patients may report cold intolerance, constipation, increased or decreased menstrual flow, and lethargy. Children will have severe growth retardation despite treatment. Inspection may show dry, pale, puffy skin and slow thought processes. Palpation may detect bradycardia.
Corticotropin deficiency. Patient history discloses fatigue, nausea, vomiting, anorexia, and weight loss. During inspection, you may note depigmentation of the skin and nipples. Vital signs during periods of stress may reflect fever and hypotension.
Prolactin deficiency. Patients commonly report absent postpartum lactation, amenorrhea, sparse or absent growth of pubic and axillary hair, and symptoms of thyroid and adrenocortical failure.
Panhypopituitarism. All six pituitary hormones are at least partially deficient. This may result in a host of mental and physical abnormalities, including lethargy, psychosis, orthostatic hypotension, bradyardia, and anemia.
