EFFECT OF GROWTH-HORMONE AND INSULIN-LIKE GROWTH FACTOR-I ON URINARY ALBUMIN EXCRETION - STUDIES IN ACROMEGALY AND GROWTH-HORMONE DEFICIENCY

Glomerular hyperfiltration is a characteristic feature of acromegaly but it is uncertain whether albuminuria is elevated in this disease. To investigate the role of abnormal growth hormone (GH) and insulin-like growth factor I (IGF-I) levels on urinary protein excretion, we measured the overnight urinary albumin excretion rate (UalbV) and creatinine clearance in 14 acromegalic patients with metabolically active disease (fasting GH > 5 ug/l and IGF-I > 2.2 kU/l), 8 GH-deficient patients and 20 control subjects. The UalbV was higher in the acromegalic patients (median 8.4 (range 4.2-68.2) mug/min) than in the GH-deficient patients (2.0 (0.9-5.9) mug/min, p < 0.001) and control subjects (3.3 (1.0-7.8) mug/min, p < 0.0 1). Five acromegalic patients had UalbV levels above the normal upper normal limit of 10 mug/min. Only one patient with concomitant untreated hypertension had persistent microalbuminuria. Creatinine clearance also was higher in the acromegalic patients (p < 0.0 5) and lower in the GH-deficient patients (p < 0.0 5) than in the control subjects. In 11 of these acromegalic cases, the lowering of GH by 63% and of IGF-I by 48%, following treatment with the somatostatin analogue (N = 10) or spontaneous pituitary infarction (N = 1), reduced the UalbV by 2 9% to 4.9 (3.1-4 5.2) mug/min (p < 0.01). Among the acromegalic patients (25 observations), the UalbV was related to GH (r = 0. 6 1. p < 0.01), IGF-I (r = 0.57, p<0.01) and creatinine clearance (r = 0.54, p < 0.01). In conclusion, circulatory GH and IGF-I levels influence albuminuria. Because persistent microalbuminuria is uncommon in acromegaly, it is unlikely that GH elevation alone predisposes to clinically important glomerular damage.