What are the possible complications of endocrine disorders in McCune-Albright syndrome (MAS)?

Updated: Jan 05, 2021
  • Author: Gabriel I Uwaifo, MD; Chief Editor: George T Griffing, MD  more...
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Hyperthyroidism in MAS can cause severe failure to thrive in infants and young children. Elevated thyroid levels result in a hypermetabolic state with possible weight loss, anxiety, tremor, tachycardia, and sleeplessness. A decreased attention span often results in poor school performance. Osteoporosis can also result from a prolonged hyperthyroid state.

Infantile Cushing syndrome is also associated with severe growth failure, though the weight-for-height percentile deviations are not as significant as those associated with hyperthyroidism in infancy. Infants with Cushing syndrome often have poor muscle tone and may have hypertension and bruise easily. Long-term untreated hypercortisolism also can result in death. Blood pressure, muscle tone, and growth should all improve with adrenalectomy, though some permanent effect on growth potential may occur.

GH excess associated with a somatotroph adenoma leads to gigantism or acromegaly, depending on the age of initial presentation. In addition to the characteristic tall stature and coarse facial features, individuals are at risk for glucose intolerance, hypertriglyceridemia, hypertension, and mild myopathy. The adenoma itself may interfere with the production of other pituitary hormones. Extension of the tumor above the sella can compromise the optic chiasm, resulting in visual field defects, most commonly bitemporal homonymous hemianopsia.

Hypophosphatemia as a result of increased urinary phosphate losses causes severe rickets and short stature. Although phosphate replacement and calcitriol treatment improve growth and heal the rickets, overall growth potential is reduced. Additionally, select patients may develop nephrocalcinosis and loss of renal function over time (iatrogenic sequelae).

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