The principal renal function tests are plasma creatinine concentration, estimated glomerular filtration rate (eGFR) calculated from the creatinine concentration result and urinalysis. Impaired filtration rate with or without proteinuria and/or haematuria is suggestive of renal disease. If eGFR is over 60 ml/minute, no further investigations or follow-up are needed, unless other signs suggestive of renal disease are present (haematuria, proteinuria, microalbuminuria in a diabetic patient).