ABSTRACT
Renal failure is classified into two main categories: acute kidney injury and chronic kidney disease. The causes of renal failure can be classified into prerenal, renal and postrenal. The effects of renal failure result from impairment of the range of normal renal functions, which can be grouped as fluid and electrolyte balance, excretion of waste products of metabolism, and endocrine functions. Many waste products such as urea and creatinine depend on glomerular filtration for their excretion, and they are not reabsorbed as avidly as the electrolytes. Consequently, creatinine and urea accumulate in proportion to the number of nephrons that have been destroyed. Major endocrine functions of the kidney include the control of red cell formation via erythropoietin synthesized in the peritubular cells and the control of arterial blood pressure via the renin–angiotensin system. Renal failure can lead to anaemia and hypertension. In early renal failure, renin is secreted from the juxtaglomerular cells in the ischaemic areas of the kidney.
