Normally a creatinine of 90 μmol/L is normal in the elderly. The normal value of blood creatinine is 53~106 μmol/L for adult men and 44~97 μmol/L for adult women in our country.Therefore, the blood creatinine of 90 μmol/L for the elderly is normal. Creatinine is the metabolic end product of creatine in muscle tissue. Creatinine does not bind with protein in the blood and can freely pass through the glomerulus, which is the most commonly used indicator to indirectly reflect the glomerular filtration function. When glomerular filtration is impaired, the body’s serum creatinine may be elevated, suggesting the presence of renal insufficiency. Creatinine 90μmol/L within the normal range can only reflect the kidney excretory capacity is still good, can not completely represent the kidney without disease, such as nephritis, kidney stones, pyelonephritis, etc., these diseases patients blood creatinine can often also be normal. Therefore, in order to clarify whether there are problems with the kidneys, it is necessary to combine with other tests such as routine urinalysis and ultrasound of the urinary system to make a comprehensive judgment. If patients need to improve the kidney function related examination, it is recommended to go to regular hospitals for consultation, and have the examination results prescribed and evaluated by professional doctors.