Tests to check kidney function in people with Diabetes
People with diabetes who don’t control their blood glucose levels, may develop a chronic complication called Diabetic Nephropathy that consists in irreversible kidney damage. This may culminate in Terminal Chronic Renal Failure and those affected will require dialysis or a kidney transplantation. Fortunately, these kidney damages can be stopped or reversed if detected early, so they won’t pose health problems that may affect your quality of life. As Nephropathy doesn’t show any signs or symptoms in its early stages, it’s important for every person with Diabetes to get a full examination of their kidney function at least once a year.
Sixty percent of people who need dialysis, are people with Diabetes, being Diabetic Nephropathy the leading cause of chronic renal failure. This doesn’t have to keep on happening, because, if people with Diabetes maintain optimal control of the blood glucose levels (glycemia) and Hemoglobin A1c, this will prevent Diabetic Nephropathy and other chronic complications.
Furthermore, if people with Diabetes get checked every year to detect their kidney function, they’ll be able to detect any kidney damage in its initial stage, being able to easily reverse the problem and maintain a good health.
When you check your renal function annually, you need to include at least the following tests, in order to rule out the presence of urine protein and albumin:
- Microalbuminuria: is a test that tells if your kidneys are functioning properly. It can detect very small amounts (traces) of protein in the urine. Normal microalbuminuria values are of 30 micrograms per milligram (mcg/mg) or less. Values above this figure are not considered normal, and your kidneys may have started damaging. At this stage Diabetic Nephropathy could be reversed with the use of a new drug known as Angiotensin II antagonists.
- Proteinuria: this is a urine test that detects if protein levels are high which may indicate irreversible kidney damage. Normal urine protein test values are 0 to 8 mg/dl. For the 24-hour test, the normal level should be less than 150 mg/dl. When people have proteinuria, progression of this damage can be delayed with the use of Angiotensin Converting Enzyme (ACE) Inhibitors.
- Creatinine: Creatinine is the result of the decomposition of Creatine, which is an important muscle component. Creatinine is a blood test that allows us to know how our kidney function is and its normal levels lay between 0.8 and 1.4 mg/dl. In women, these values may vary, because they usually have lower levels than men. Creatinine values of 1.4 mg/dl or more, indicate failure in renal function due to one or more of the following conditions: Diabetic Nephropathy, Eclampsia, Preeclampsia, Pyelonephritis, Muscular Dystrophy, Glomerulonephritis, Acute Tubular Necrosis, Urinary Tract Obstruction, Rhabdomyolysis, Renal Failure and Dehydration.
- Albumin is a blood test used to detect kidney damage. Normal blood albumin values are of 3.4 to 5.4 g/dl (34 to 54g/l). Any level below this range indicates possible kidney damage.
- BUN: The BUN test or blood urea nitrogen, substance formed when protein breaks down, can tell us how our kidneys are functioning. Normal BUN values range between 6 to 20 mg/dl. Elevated levels may indicate kidney damage.
If your doctor observes that any of these tests is off normal values, he needs to refer you to a Nephrologist or kidney specialist, who will perform additional evaluations which may include:
- Glomerular filtration rate: This is a test that measures the degree of creatinine filtration by the glomeruli found in the kidneys. When the kidneys aren’t functioning properly creatinine levels rise in the blood. This test helps us figure out what the filtration degree of the glomeruli is, allowing to predict any damage even before it happens, and if it already exists, it can determine the degree of progress. Normal results vary between 90 and 120 mL/min. Levels below 60 mL/min for three or more months are a sign of chronic kidney disease. GFR results below 15 mL/min immediately indicate chronic renal failure. Older people will have below normal GFR levels because these decrease with age.
- 24-hour urine collection: this is a test used to measure the amount of urine and substances eliminated through it, over a 24-hour period. This test can help diagnose problems such as kidney damage and Diabetes insipidus, and involves a high fluid intake and the use of diuretic medications. Normal values range between 800 and 2000 milliliters per day (with a consumption of 2 liters of liquids per day).
- Electrophoresis analysis of urine proteins: this is a urine test that determines the amount of certain proteins such as albumin and globulins which are expelled through urine. An electrophoresis analysis of urine proteins is performed to determine the cause and amount of these proteins expelled through urine. Normal urinary albumin values lie at 5 mg/dl or less. Urinary albumin values greater than 5 mg/dl may indicate the presence of Diabetic Nephropathy or renal failure, nephrotic syndrome, acute urinary tract infection, acute inflammation, multiple myeloma and amyloidosis.
- Creatinine Clearance: Creatinine clearance is a test that compares blood and urine creatinine levels, and estimate the glomerular filtration rate (GFR). Given that the kidney’s filter tube secretes a small amount of creatinine, this test doesn’t accurately reflect the glomerular filtration rate. Normal test values for creatinine clearance lie between 97 and 137 ml/min in men and 89 to 128 ml/min in women. Values below normal indicate acute renal failure, chronic renal failure, congestive heart failure, acute tubular necrosis, bladder outlet obstruction, glomerulonephritis, renal ischemia, dehydration and shock, among others.
Other important tests your nephrologist may prescribe are: Phosphorus, calcium, bicarbonate, PTH and potassium blood levels, Hemoglobin, Hematocrit, Renal arteriography, Renal scintigraphy and kidney biopsy.
Some of the signs or symptoms that may indicate Diabetic Nephropathy or kidney damage are high blood pressure, leg swelling or edema, weight gain, loss of appetite, body itching, weakness, leg cramps, nausea and vomiting. Unfortunately, these signs and symptoms usually appear when kidney damage is already irreversible, so early renal function detection through screening and testing performed yearly will allow you to address the problem when the damage can be reversed without affecting your quality of life.
On Diabetes Up to Date, we are committed to provide you with all of the necessary knowledge to prevent the dreaded chronic complications associated with poorly controlled Diabetes so you can enjoy a healthy, productive and happy life.