The evaluation of a patient with suspected acromegaly begins with a determination of the fasting GH level along with a complete assessment of anterior pituitary function (see Chap. 17). Additional testing should include the measurement of serum insulin-like growth factor-I (IGF-I, somatomedin C). Failure of suppression of GH levels to <3 ng/mL after oral administration of glucose can be helpful diagnostically, especially in patients with normal fasting GH or IGF-I levels who appear to be clinically symptomatic. A paradoxical rise in GH levels is seen after the intravenous administration of TRH in half of the patients. This test can be included in the preoperative evaluation.

First-line therapy for patients with acromegaly should be transsphenoidal surgery, especially if a microadenoma or small macroadenoma without invasion of the cavernous sinus is present.30 Medical therapy as a primary treatment modality should be reserved for those in whom surgery cannot be safely undertaken.

In the postoperative evaluation of the patient with acromegaly, the goals are a fasting GH level of <5 ng/mL and normalization of the IGF-I level. The restoration of normal GH dynamics, with a glucose-induced suppression of the serum GH level to <3 ng/mL after an oral glucose load, is desirable; however, in the author’s experience, the absence of such normalization does not necessarily imply residual tumor or recurrence. Importantly, normalization of GH and IGF-I levels may first occur as long as 3 to 6 months after surgery. Thus, if these values are elevated in the immediate postoperative period, a failure of surgery is not inevitable.