The correct answer is E. This patient has acromegaly, an excess of growth hormone, evidenced by increased hand and foot size and coarse facial features with a protruding jaw. Other features, such as tooth-space widening and macroglossia, can be present. Impaired glucose tolerance is often present, as is diabetes. Hypertension is present in 1/3 of these patients. Complaints of headache and visual field losses can occur. Patients may have carpal tunnel syndrome. The test of choice for diagnosis is insulin-like growth factor, which is elevated >5 times the normal limit. Another test which can be used for diagnosis is measurement of growth hormone after the administration of 75 g of glucose. In a normal patient, the growth hormone level would be suppressed, but in a patient with acromegaly, the levels remain high (greater than 5 ng/mL).
Cortisol levels (choice A) might be helpful as part of the diagnosis of Cushing syndrome. Cushing syndrome can be associated with insulin resistance, hypertension, and weight gain but doesn't share other features associated with acromegaly.
CT scan of the brain (choice B) would likely reveal a macroadenoma in this patient. A CT scan (or other imaging) should be done to confirm most endocrine disorders only after they are suggested serologically. This is to avoid confusion of incidentally discovered tumors that are unrelated to the patient condition but can certainly lead one down an incorrect course.
Fasting glucose level (choice C) is a useful screening test for diabetes. It is likely that our patient has diabetes secondary to his acromegaly as evidenced by his polyuria and polydipsia. It is appropriate to measure fasting glucose levels in this patient, but it is not the test to diagnose the patient's underlying primary medical problem.
Growth hormone levels (choice D) should not be used as a screening test to diagnose acromegaly, because patients have a normal daily fluctuation of gonadotropin-releasing hormone (GNRH) and growth hormone. Growth hormone levels can also fluctuate with exercise and acute illness. Pregnant and adolescent patients can also have increased levels and not have acromegaly. A lack of the normal nadir may be useful in identifying patients who have acromegaly, because these patients will not have full suppression of growth hormone throughout the 24-hour period.
PEARL: Acromegaly is a condition in which there is abnormal increased release of growth hormone from the pituitary gland. It is associated with increased morbidity and mortality. Clinical presentations of this condition include increased growth noted in the extremities, carpal tunnel syndrome, arthralgias, glucose intolerance or overt diabetes, hypertension, sleep apnea, and colonic polyp (increased risk for colon cancer as a result). The serum insulin-like growth factor (IGF-1) is increased in the serum, and a random measurement of growth hormone in the serum never falls below 0.4 micrograms. An oral glucose tolerance test may be used to confirm this diagnosis. Trans-sphenoidal surgery may be curative to remove the pituitary adenoma. If surgery fails to correct this problem, the patient may be treated with the somatostatin analog octreotide (Sandostatin) or carbegoline (Dostinex) if prolactin secretion is also part of the abnormal pituitary function.
