AcromegalyDz

Synonyms: Gigantism, acromegalia.

ICD-9 Code: 253.0
ICD-10 Code: E22.0

Definition: Acromegaly is caused by overproduction of growth hormone, most commonly by a benign pituitary tumor (pituitary adenoma). Acromegaly may be accompanied by distinct findings in the musculoskeletal system that may contribute to early detection and diagnosis.

Cardinal Findings: Excess growth hormone causes acromegaly in adults and, if the onset is before epiphyseal closure, gigantism in children. Clinically, patients develop distinctive coarse facial features; thickening of the skin; enlarged mandible, hands, and feet; prominent forehead and supraorbital ridging; enlarged tongue and enlarged viscera; hirsutism; oily skin; and excessive sweating. The musculoskeletal complaints result from premature osteoarthritis, kyphosis of the spine, pseudogout, entrapment neuropathies [e.g., carpal tunnel syndrome (CTS)]. Many patients complain of nonspecific arthralgias affecting the shoulder, knees, hips, and spine.

Complications: Increased cardiovascular morbidity and mortality from hypertension, cardiomyopathy, heart failure, or valvular regurgitation. Patients may also develop diabetes (25%), galactorrhea (5%), parathyroid and islet cell adenomas, or sleep apnea.

Diagnostic Tests: Single measures of serum GH are highly variable, even in normal persons. Serum levels of insulin-like growth factor-1 (IGF-1; also known as Somatomedin C)  are more sensitive and cost-effective than serum growth hormone levels.

Imaging: Radiographic findings of the joints may be diagnostic and include generalized widening of the joint spaces because of overgrowth of cartilage. Bone remodeling and spur formation are common. Look for widening/prominence of phalangeal tufts or vertebral “scalloping” (exaggerated posterior vertebral concavity), especially in the lumbar spine. In later stages of the disease, OA is obvious. In some cases, deposition of calcium pyrophosphate within joint tissues can lead to the clinical syndrome of pseudogout. MRI is the modality of choice to assess the sella turcica, and to detect a pituitary tumor.

Therapy: Treatment goals include (1) normalization of growth hormone activity, (2) tumor mass reduction, and (3) preservation of pituitary function. Surgical (transsphenoidal) resection of the pituitary tumor may be followed by radiation therapy. There are several categories of pharmacotherapy, including: 1) somatostatin analogues (octreotide, lanreotide), 2) dopamine agonists (bromocoptine, cabergoline; these are especially useful for patients with tumors that also secrete prolactin and 3) growth hormone receptor antagonist (pegvisomant). These approaches are often successful at normalizing GH activity; they can also be used pre-operatively and/ot post-operatively for patients with operable tumors.

Prognosis: While the disease can be controlled, in most cases the joint findings of acromegaly are not reversed with correction of growth hormone overproduction. One exception is the commonly observed CTS, which may improve after surgical or medical ablation of the pituitary tumor.

BIBLIOGRAPHY

Melmed S. Acromegaly. N Engl J Med 1990;322:966. PMID: 2179724

Clemmons DR. Optimizing control of acromegaly: integrating a growth hormone receptor antagonist into the treatment algorithm. J Clin Endocrinol Metab 2003;88:4759–3767. PMID: 14557452