Renal pathology in rats bearing tumour-secreting growth hormone

The effects of growth hormone (GH) on renal structure and function were investigated in rats aged 10-16 weeks bearing a tumour secreting GH. Body weight gain, food intake, urine volume, and urinary excretion of creatinine and urea nitrogen were significantly greater in tumour-bearing rats than in controls. The tumour-bearing rats presented progressive proteinuria, hyperproteinaemia, and hyperlipidaemia. Creatinine clearance was significantly higher in experimental animals during the early experimental stage, but decreased as the glomerular lesions progressed, associated with a rise in serum creatinine levels. The glomeruli became progressively enlarged with degenerative changes of the visceral epithelial cells and capsular adhesions. In advanced stages proteinaceous material invaded the subcapsular space and the capillary lumen collapsed finally leading to glomerulosclerosis. Except for the presence of proteinaceous material and damaged epithelial cells the glomerular lesions resemble those observed experimentally after reduction of renal mass, and in diabetes mellitus. We speculate that the pathological features described are due to effects of persistently high levels of circulating GH on the glomerular cells.