If a person has been diagnosed with a kidney disease, several laboratory tests may be ordered to help monitor kidney function. Some of these include:

(1) Blood levels of BUN and creatinine are measured from time to time to see if the kidney disease is getting worse.

(2) The amount of calcium and phosphorus in the blood, blood gases (ABGs), and the balance of serum and urine electrolytes can also be measured as these are often affected by kidney disease.

(3) Hemoglobin in the blood, measured as part of a complete blood count (CBC), may also be evaluated as the kidneys make a hormone, erythropoietin, that controls red blood cell production and this may be affected by kidney damage.

(4) Erythropoietin may be measured directly, although this is not a routine test.

(5) Parathyroid hormone (PTH), which controls calcium levels, is often increased in kidney disease and may be checked to help determine if enough calcium and vitamin D are being taken to prevent bone damage.

(6) Cystatin C is another test that may sometimes be used as an alternative to creatinine to screen for and monitor kidney dysfunction in those with known or suspected kidney diseases.

(7) Both blood and urine beta 2 microglobulin (B2M) tests may be ordered along with other kidney function tests to evaluate kidney damage and disease and to distinguish between disorders that affect the glomeruli and the renal tubules. Normally, only small amounts of B2M are present in the urine, but when the renal tubules become damaged or diseased, B2M concentrations increase due to the decreased ability to reabsorb this protein. When the glomeruli in the kidneys are damaged, they are unable to filter out B2M, so the level in the blood rises. B2M tests may sometimes be ordered to monitor people who have had a kidney transplant, to detect early signs of rejection, and ordered to monitor people who are exposed to high levels of cadmium and mercury, such as with occupational exposure.