age urine creatinine
QUANTITATIVE LABORATORY TESTING. The first-line test is 24-hour quantitative urine protein excretion. In children, the amount of urinary protein excretion varies by age and body size. The normal amount is less than 4 mg per m 2 per hour or 100 mg per m 2 per day. The mean concentrations and the 5th to 95th percentile values of urine albumin and creatinine as well as the ACR values are presented by sex and age (Table 2. Table 2. Distribution of urine albumin and creatinine concentrations for male and female children in the different age groups. The reference value for the urine albumin/creatinine ratio (ACR) varies between races and has not been previously validated in children. We assessed the ACR reference values and the factors that affect them in a population of healthy Chinese children. A 24-hour urine protein excretion test is often difficult in children. Spot, first-morning urine testing for UPr/Cr is more useful and correlates well with the 24-hour urine collection. Spot, first-morning urine testing should be used in children if the urine dipstick test result is 1+ or more. The presence of protein in urine is a common laboratory finding in children. Although proteinuria is usually benign, the condition can be a marker for a serious underlying renal disease or systemic disorder. 1, 2 When proteinuria coexists with hematuria, the likelihood of clinically significant renal disease is higher. It can be calculated (estimated) by a formula using serum (blood) creatinine level, patient's weight, and age. The formula is 140 minus the patient's age in years times their weight in kilograms (times 0.85 for women), divided by 72 times the serum creatinine level in mg/dL. Creatinine clearance can also be more directly measured by collecting a 24-hour urine sample and then drawing a blood sample. The creatinine levels in both urine and blood are determined and compared. Normal creatinine clearance for healthy women is 88-128 mL/min. and 97 to 137 mL/min. in males (normal levels may vary slightly between labs). Blood urea nitrogen (BUN) level is another indicator of kidney function. The kidneys maintain the blood creatinine in a normal range. Creatinine has been found to be a fairly reliable indicator of kidney function. Elevated creatinine level signifies impaired kidney function or kidney disease. Proteinuria may occur secondary to glomerular or tubular dysfunction. Although a 24-hour urine protein excretion test is usually recommended, it may be impractical in children. A spot, first-morning urine test for protein/creatinine ratio can be useful in this situation. Proteinuria is usually benign, in the form of transient or orthostatic proteinuria. Persistent proteinuria may be associated with more serious renal diseases. The measurement of creatinine can aid in establishing if any of these products were used. Creatinine production and excretion is directly related to muscle mass and is sex and age dependent. Normal random urine creatinine concentrations range from 40-300 mg/dL in males and 37-250 mg/dL in females. Values as low as 17 mg/dL have been observed in rare instances. Certain physiological conditions such as diabetes may result in consistently dilute urine specimens.
For healthy women is 88-128 mL/min. and 97 to 137 mL/min. in males.