The assay of urinary growth hormone in normal and acromegalic adults

OBJECTIVES: To establish a normal range for urinary growth hormone in adults and to investigate the urinary growth hormone levels in patients with acromegaly, comparing these with the serum growth hormone results of a glucose tolerance test. We also studied the molecular identity of the growth hormone recognized by our assay method. DESIGN: Overnight urine samples and, in some cases, timed urine samples taken during the day were obtained from healthy volunteers and acromegalic patients. A standard glucose tolerance test with serum growth hormone measurements was performed on the acromegalic patients. PATIENTS: One hundred and thirty-five normal adults and 33 acromegalic patients were studied. MEASUREMENTS: Urinary growth hormone was measured using a sensitive and precise assay developed previously. RESULTS: In healthy volunteers overnight urinary growth hormone values fell gradually with increasing age, but there was no significant difference between men and women in any decade or between smokers and non-smokers. Sexual intercourse had no detectable effect on the values, but there was a large increase following strenuous exercise. Studies of the diurnal patterns in normal and abnormal adults suggested that it might be possible to diagnose acromegaly on a random urine sample. Gel filtration studies on a urine sample from an acromegalic patient showed a single peak of molecular weight 22,000. Using overnight collections there was clear discrimination between the values given by the normal adults and the acromegalic patients and an excellent correlation between urinary growth hormone levels in acromegalic patients and the mean serum growth hormone in a glucose tolerance test. CONCLUSIONS: In contrast to some other groups we conclude that urinary growth hormone provides a useful, non-invasive screening test for acromegaly, but this conclusion depends crucially on the assay being sensitive and precise at low values.