Test |
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What it Means |
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Normal Levels |
Serum Creatinine |
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Creatinine is a waste product that is made when your body breaks down protein you eat and when muscles are injured. A high serum (blood) creatinine level means kidney damage. Creatinine levels may vary somewhat, even when the kidneys work normally. So, your doctor should check your level more than once before diagnosing CKD (Chronic kidney Disease). Measuring creatinine is only the first step to finding your level of kidney function.
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The normal serum creatinine range for men is 0.5-1.5 mg/dL. The normal range for women is 0.6-1.2 mg/dL. |
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Creatinine Clearance |
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Creatinine clearance is a test sometimes used to estimate filtering capacity of the kidneys. The amount of creatinine in your urine is compared to the amount of creatinine in your blood. Your doctor may test your urine by asking you to collect your urine for 24 hours in a special container.
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Normal creatinine clearance for healthy men is 97-137 mL/min. Normal creatinine clearance for healthy women is 88-128 mL/min
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Glomerular Filtration Rate (GFR) |
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GFR is a more accurate way to measure how well your kidneys filter wastes from your blood. Your GFR gives your doctor an idea of the speed at which your kidneys are failing, and whether you are at risk for complications of kidney disease. GFR can be estimated from serum creatinine, using a formula. |
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Healthy adults have a GFR of about 140*; normal is greater than 90. Children and the elderly usually have lower GFR levels. A GFR less than 15 is kidney failure. *GFR is reported in mL/min/1.73 m2.
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Urine Albumin |
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Inside healthy kidneys, tiny filtering units called nephrons filter out wastes but keep in large molecules, like red blood cells and albumin (protein). Some kidney diseases damage these filters so albumin and other proteins can leak into the urine. Protein—albumin—in the urine can be a sign of kidney disease. Albumin can be measured with a urine dipstick or a 24-hour urine collection to find out how much protein is "spilling" into the urine. Albumin levels can increase with heavy exercise, poor blood sugar control, urinary tract infections, and other illnesses.
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In a 24-hour urine sample, a normal level is less than 30 mg/day. |
Microalbuminuria |
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Microscopic amounts of protein too small to be measured with a standard dipstick test can be an early sign of kidney disease—especially in people with diabetes. Special dipsticks or laboratory tests can find microalbuminuria. The American Diabetes Association guidelines recommend that anyone with type 1 or type 2 diabetes have a test for microalbuminuria at least yearly.
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Urine in healthy people contains less than 150 mg/L of albumin. |
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Blood Urea Nitrogen (BUN) |
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Blood Urea Nitrogen (BUN) is another measure of wastes (urea) in the blood. Urea is produced from the breakdown of protein already in the body and protein in your diet. A high BUN usually means that kidney function is less than normal, but other factors may affect the BUN level. Bleeding in the intestines, congestive heart failure, and certain medications may make the BUN higher than normal. As BUN rises, symptoms of kidney disease may appear, such as a bad taste in the mouth, poor appetite, nausea, and vomiting. In dialysis, BUN is used to measure whether a person is receiving the correct amount of dialysis. Sometimes a low BUN may also mean that you are not eating enough protein |
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The normal BUN level for healthy individuals is 7-20 mg/dL in adults, and 5-18 mg/dL in children. Patients on dialysis have higher BUN levels, usually 40-60 mg/dL. The nephrologist (kidney doctor) and dietitian will help determine whether the BUN is in the correct range
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