Millions of people have or are at risk chronic kidney disease (CKD) but don’t know it. Because kidney disease is usually silent until very late in the process, the National Kidney Foundation (NKF) strongly advocates that people at higher risk for kidney disease be screened. To help primary care doctors and other health professionals better do this, the NKF recently published in the August 2007 edition of the American Journal of Kidney Diseases their position statement on testing for kidney disease.

Screening for Kidney Disease

Screening is critical for early diagnosis, evaluation and treatment of kidney disease. CKD is usually diagnosed by the presence of kidney damage and/or a decrease in the level of kidney function. In the majority of cases, this can be done by checking for protein in the urine (i.e. kidney damage) and/or a low GFR (i.e. decreased function). Because no test is perfect, doctors need to be careful not to over-diagnose kidney disease. This means that these tests should generally be limited to people at higher risk for kidney disease (i.e. have risk factors). Equally important, doctors need to take into account the person’s medical history or clinical situation when interpreting the results.

Checking for Kidney Damage

It is recommended that all health care providers, not just kidney doctors, recognize when their patients are at high risk for kidney damage or disease. Patients at risk should have a small amount of their urine checked for protein or albumin. If none is found, testing should be repeated yearly. If protein is present but likely to have been caused by a temporary condition (e.g. urinary tract infection), it should be repeated after the condition has cleared up. If a reversible condition cannot be found, the urine should be rechecked twice over the next 3-6 months. If two of the three tests show a significant amount of protein is present, a diagnosis of kidney damage can be made and the person treated or referred to a kidney doctor.

Checking for Reduced Kidney Function

Patients at risk for kidney disease or have signs of kidney damage (i.e. blood or protein in the urine) should have their kidney function assessed. Currently the best method is to do estimate the GFR by measuring the amount of creatinine in the blood (i.e. serum creatinine) and then using a specific mathematical formula (i.e. MDRD equation) to adjust for the person’s age, gender, race, and body size. If the person is at risk and the GFR is less than 60 (or 60 mL/min/1.73m²), then the doctor should act. If the GFR is above 60, there aren’t other signs of kidney damage or dysfunction and the person is not at a high risk for developing severe kidney failure, it may prudent to monitor the situation instead of starting treatment or sending them to the kidney doctor. In these cases, it is recommended that the person’s medications be adjusted, substances known to be toxic to the kidney avoided, and the GFR be checked more frequently. If the GFR is or starts to rapidly drop without explanation (i.e. more than 30% within 4 months), then it is appropriate to start treatment or refer to the kidney doctor.

• Symptoms of Kidney Disease
• Tests / Diagnosis For Kidney Disease
• Testing for Protein in Urine
• Glomerular Filtration Rate (GFR)
• Normal GFR Adjusted for Age