One complication of diabetes is diabetic nephropathy. A quick and simple way to check renal function is to draw a blood sample for serum creatinine and BUN tests. These tests should be performed when the patient is diagnosed with diabetes.Although the serum creatinine and BUN tests can quickly reveal the patient’s renal function, serum creatinine is the more sensitive indicator. Many extrarenal conditions, such as dehydration, can elevate the BUN level, but serum creatinine changes little except in renal disease. A normal serum creatinine level for an adult ranges between 0.7 and 1.5 mgjdl (0.6 and 1.2 mg/dl for adults over age 65). A normal BUN level for an adult ranges between 4 and 22 mg/dl (8 and 18 mgjdl for adults over age 65). Elevations in your patient’s serum creatinine and BUN levels require further testing before a physician can make a diagnosis of diabetic nephropathy

Nursing Considerations

Test results are more accurate if your patient fasts for 8 hours beforehand; therefore, try to schedule the test for first thing in the morning, so that most of the fasting time will occur while she is sleeping. Tell her not to eat breakfast.

If your patient is taking ascorbic acid, a barbiturate, or a diuretic, her physician will probably withhold it until after the test because these drugs can raise serum creatinine levels. Note whether your patient is receiving amphotericin B, an aminoglycoside, methicillin, or chloramphenicol. Any of these nephrotoxic drugs could be the source of her renal impairment.

After drawing the blood, send the sample to the laboratory immediately. To prevent hemolysis, which can alter the test results, handle the blood sample gently.

If the BUN level is elevated but the serum creatinine level isn’t, consider possible extrarenal causes before repeating the tests. Also, keep in mind that the amount of creatinine produced in the body is related to muscle mass. Therefore, an athlete with normal renal function may have elevated levels of serum creatinine.

If your patient’s serum creatinine and BUN levels are both high, check them frequently to monitor her renal function. Abnormal renal function coupled with diabetes places your patient at increased risk for endstage renal disease and cardiovascular disease. The frequency of these tests depends on how high the patient’s serum creatinine and BUN levels are and whether she exhibits other signs.