Saline depletion, pre-renal failure and acute renal failure

The wide range of diseases that can influence the kidney, either directly or indirectly, all influence water and electrolyte balances according to established 'rules'. There is great scope for helping patients by understanding these rules, and also a great potential to do harm by ignoring them. Careful consideration of simple routine data, and an awareness of the limitations of some indexes and ratios in common use, will usually result in an adequate provisional classification of the patient. This can be used to plan therapeutic trials designed to correct metabolic and electrolytic disturbances, and to organize diagnostic procedures that will establish the cause of any intrinsic renal diseases or the cause of obstructions. Earlier and more frequent use of dialysis and related techniques in management is recommended, as is greater attention to the control of blood glucose, nutrition and electrolyte balance. A general recommendation is that corrections of many deficits should not be excessively rapid.