Physicians learn to routinely monitor kidney indicatorsbecause of how common kidney-function problems are and how serious they can become. Kidney failure can cause a wide range of symptoms. Particularly, when clinicians note signs suchas fatigue (often due to anemia), fluid retention and changes in urinary patterns (or blood in the urine) and note risk factors, such as hypertension, diabetes, or vascular disease, they know to be especially vigilant and to do additional testing.
Urine and blood tests are usually the first-line diagnostics. An unusual amount of a protein called albumin in the urine can be the best initial screening test, as it is a sign that the kidneys are not filtering correctly. The physician and laboratory can also use techniques to estimate the kidney filtration rate.
|Checking the urine for albumin-a simple test-can detect kidney disease at its earliest stage, when intervention is easiest.|
In addition, the doctor will get a blood measurement of serum creatinine and also blood urea nitrogen (BUN), two breakdown products of protein that the kidney should mostly filter out. Concentrations of potassium, calcium, phosphates and red blood cells can also be important indicators, as can blood acidity.
If these signs, risk factors and tests indicate compromised kidney function, the medical team may chose to use ultrasound to see if the kidneys have changed in size or have any obstructions. Sometimes the team will also need to take a small sample (biopsy) of the kidney with a fine needle, especially if the cause of the kidney problem is unclear. (This is normally a simple outpatient procedure requiring local anesthesia only.)
Finally, if the patient’s kidney disease appears to be of acute onset, the kidney disease team may choose to test for urologic obstructions such as kidney Stones or in some cases may perform an angiogram or other radiologic test to look for renal artery narrowing.
Physicians evaluating kidney disease will assign each patient a stage according to the severity of the disease, on 1-5 scale (with 5 being most advanced):
- Stage 1 – kidney damage (protein in the urine) with normal filtration rate.
- Stage 2 – kidney damage with mild decrease in filtration rate.
- Stage 3 – moderate decrease in filtration rate.
- Stage 4 – severe reduction in filtration rate.
- Stage 5 – kidney failure.