Which diagnostic step is first recommended for suspected acromegaly?

When considering a diagnosis of acromegaly, measuring IGF-1 (Insulin-like Growth Factor 1) levels is the first and most appropriate step. IGF-1 is a hormone that reflects the levels of growth hormone (GH) released from the pituitary gland and remains elevated in patients with acromegaly due to excessive GH production.

This measurement is crucial because it provides a reliable indication of GH activity, is less susceptible to fluctuations based on time of day or feeding compared to measuring GH alone, and is thus a better initial screening tool. If the IGF-1 level is indeed elevated, it typically leads to further testing, including glucose suppression tests or imaging studies like MRI or CT scans to assess the pituitary gland for potential tumors.

Other diagnostic steps, such as the glucose suppression test, are performed after initial screening if IGF-1 levels indicate a problem. Imaging studies like MRI and cranial CT scans are used later to visualize the pituitary gland and confirm the presence of an adenoma but are not the first step in the diagnostic process.