In the original manuscript, it was shown to be more accurate than the Cockcroft-Gault and Jelliffe equations using actual body weight, which is an unfair comparator. This equation was developed in the late 1980’s for the purposes of estimating renal function in obese (BMI ≥ 30 m 2) patients. Don’t use the Salazar-Corcoran equation for obese patients.Currently, the National Kidney Foundation recommends MDRD/CKD-EPI for evaluating the progression of renal function, and C-G for dosing medications. Although the Cockcroft-Gault equation is less accurate than newer methods (MDRD and CKD-EPI) for estimating renal function, drug manufacturers typically use the older C-G method to determine renal adjustments of medications. Cockcroft-Gault is still the best equation for renally adjusting medications.The following are the top 10 facts that every clinician should know about creatinine clearance: A standard blood test is used to measure creatinine levels in your blood (serum creatinine).Evaluating renal function for the purposes of drug dosing is a common task for clinical pharmacists, but a number of misconceptions have developed over the past forty years as the process of evaluating renal function has improved. Your doctor may ask you not to eat (fast) overnight before the test.įor a creatinine urine test, you may need to collect urine over 24 hours in containers provided by the clinic.įor either test, you may need to avoid eating meat for a certain period before the test. If you take a creatine supplement, you'll likely need to stop use. What you can expectįor a serum creatinine test, a member of your health care team takes a blood sample by inserting a needle into a vein in your arm.įor a urine test, you’ll need to provide a single sample in the clinic or collect samples at home over 24 hours and return them to the clinic. Results from creatinine in blood or urine are measured and interpreted in many ways, including the following: Serum creatinine levelĬreatinine usually enters your bloodstream and is filtered from the bloodstream at a generally constant rate. The amount of creatinine in your blood should be relatively stable. An increased level of creatinine may be a sign of poor kidney function. The typical range for serum creatinine is: Serum creatinine is reported as milligrams of creatinine to a deciliter of blood (mg/dL) or micromoles of creatinine to a liter of blood (micromoles/L). The measure of serum creatinine may also be used to estimate how quickly the kidneys filter blood (glomerular filtration rate). The formula for calculating GFR takes into account the serum creatinine count and other factors, such as age and sex.īecause of variability in serum creatinine from one person to another, the GFR may provide a more accurate reading on kidney function. A GFR score below 60 suggests kidney disease. The range of scores below 60 may be used to monitor treatment and disease progression. Creatinine clearanceĬreatinine clearance is a measure of how well the kidneys filter creatinine out of the bloodstream for excretion in urine.Ĭreatinine clearance is usually determined from a measurement of creatinine in a 24-hour urine sample and from a serum sample taken during the same time period. However, shorter time periods for urine samples may be used. Accurate timing and collection of the urine sample is important.Ĭreatinine clearance is reported as milliliters of creatinine per minute per body surface area (mL/min/BSA).
The typical range, by age, for creatinine clearance in women is as follows: The typical range for men, 19 to 75 years old, is 77 to 160 mL/min/BSA. Standard measures have not been determined for older adults. Results lower than the typical range for your age group may be a sign of poor kidney function or conditions that affect blood flow to your kidneys. Albumin/creatinine ratioĪnother interpretation of urine creatinine count is called the albumin/creatinine ratio. Healthy kidneys generally don't filter it out of the blood, so there should be little to no albumin found in the urine.Īlbumin/creatinine ratio describes how much albumin is in a urine sample relative to how much creatinine there is. The results are reported as the number of milligrams (mg) of albumin for every gram (g) of creatinine. Results indicating a healthy kidney are:Ī higher than typical result may be a sign of kidney disease. In particular, the result may indicate a complication of diabetes called diabetic nephropathy, or diabetic kidney disease.
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