Insulin-like growth factor-I (IGF-I) has been advocated as a simple and reliable test for confirming the diagnosis of acromegaly and following a patient's response to treatment. We describe an elderly woman admitted to the hospital with altered mental status, congestive heart failure, and arthritis who was noted to have clear features of acromegaly. An IGF-I level was in the normal range, while results of an oral glucose tolerance test were diagnostic of acromegaly. As her medical condition, mobility, and nutrition improved, her IGF-I level increased above the normal range and continued to rise when she was seen as an outpatient. Therefore, illness, physical activity, nutritional status, and advanced age must be considered when interpreting IGF-I levels in patients with known or suspected acromegaly.
(Arch Intern Med. 1994;154:1533-1535)