OBJECTIVES: I. Compare growth hormone (GH) levels at baseline and after glucose suppression measured with both a polyclonal radioimmunoassay and a highly sensitive immunoradiometric assay (IRMA) in patients with acromegaly and normal volunteers.

II. Measure the levels of IGF-I and its binding protein, IGFBP-3, in these cohorts.

III. Determine any correlation between levels of IGF-I and IGFBP-3 and GH suppressibility as assessed by sensitive IRMA.

IV. Determine if patients who demonstrate biochemical features of mild GH excess are at risk for progression to active disease.

PROTOCOL OUTLINE: Blood samples are collected and assessed for growth hormone and IGF-I by polyclonal radioimmunoassay (RIA) and immunoradiometric assay (IRMA). Growth hormone is measured at baseline and 60, 90, and 120 minutes after a 100 g glucose drink. Serum glucose is measured at baseline and at 2 hours post dextrose administration by the glucose hexokinase method.

Clinical scores are determined for headache, perspiration, fatigue, joint pain, and acne.

Exams and tests may be repeated every 6 months for 2 years.

PROTOCOL ENTRY CRITERIA:

--Disease Characteristics--

Diagnosis of acromegaly and treated with transsphenoidal surgery

Biochemically and histologically confirmed growth hormone secreting tumor

OR

Healthy volunteers

--Prior/Concurrent Therapy--

Surgery:

• See Disease Characteristics
• Greater than 6 months since prior surgery

Other: At least 1 month since prior bromocriptine or octreotide

--Patient Characteristics--

Performance status: Ambulatory

Hepatic: No active hepatic disease

Renal: No active renal disease

Other:

• No diabetes mellitus
• No glucose intolerance
• Hypopituitarism allowed if on stable doses of replacement therapy