An approximation of the function of the kidney can be calculated from the serum creatinine based on the formula of Cockcroft and Gault. This formula is reasonably accurate except in patients with advanced renal impairment where the 24 hour urine collection for creatinine clearance is better. Clinical findings Polyuria and nocturia can be early clinical warning signs of the onset of renal impairment as the classical uraemic symptoms such as fatigue, dysponea, ankle oedema, anorexia, pruritis and inability to concentrate develop only in advanced renal impairment. Specific renal diseases will produce their own symptoms and signs, e.g. abdominal fullness in polycystic kidney disease. However this is outside the scope of this article.
Physical signs are usually non specific in most cases with no physical signs.
Occasionally chronic renal failure may manifest as skin pallor due to chronic anaemia, or as yellowish brown shin discoloration and nail dystrophy due to uraemia. The blood pressure is usually raised. Diabetic patients usually have evidence of diabetic retinopathy and neuropathy. It is particularly important to try to detect any potentially reversible cause of renal failure such as urinary tract obstruction. Conclusion Renal disease can be detected early using simple screening tests.