Hundreds of waste substances and fluid are excreted from the body via the kidneys. Because of this urine tests for particular by-products can provide information about a wide range of conditions. Occasionally urine tests are necessary to complement far more commonly used blood tests. Frequently urine tests are used to examine kidney function, or liver and kidney function(s). This may be part of an assessment before starting treatment with medications that are potentially toxic to the kidneys and/or liver, or to monitor such treatment schemes.
In the context of an oral and maxillofacial surgery clinic only few urine tests are commonly used.
Urine glucose test
Normally there is no glucose carried in urine. Testing urine for glucose used to be the standard screening test for diabetes. It is less accurate than the corresponding blood test which nowadays is the standard test for diabetes. Under normal circumstances glucose is only detected in urine when there are very high levels of glucose in the blood, when even healthy kidneys cannot filter out the excessive amounts. Therefore glucose in urine most commonly indicates untreated diabetes. There may, however, be rare kidney conditions where glucose is released by the kidneys even if blood glucose levels are low or normal (renal glycosuria; a malfunction of the renal tubules, part of the filtering components in the kidneys).
24h urea and/or creatinine urine test
This test requires you to collect your urine over a period of 24h. You may be given a container. The test determines the total amount of urea and/or creatinine that is excreted over this period of time and normally complements a previous blood test [diagnosis-tests-blood-biochem-level3] for urea and/or creatinine.
Creatinine is a waste product from muscle metabolism. High levels of creatinine may indicate a range of kidney conditions, muscular dystrophy or some autoimmune conditions that lead to muscle weakening. A diet very high in protein may also account for high creatinine levels in urine.
Urea is the main water-soluble waste product from the kidneys excreted into urine. Urea is the end product of protein metabolism. Abnormal amounts of urea can indicate kidney problems or may arise from too high or too low dietary protein intake.
Bence Jones protein
The Bence Jones protein is not normally found in urine. A urine test looking for this protein may follow an immunoglobulin (Ig) blood test with irregular results.
Presence of the Bence Jones protein, also known as IgM, in urine suggests multiple myeloma, a malignancy of the blood plasma cells. The neoplastic myeloma plasma cells (mostly in bone marrow) produce this particular type of Ig protein, but no other functional Igs as would be necessary for a healthy immune system. The test is used to diagnose multiple myeloma and to monitor the condition, as well as potential kidney failure.
High levels of IgM in urine may also be related to a rare form of lymphoma, a malignancy of the lymphocytes which then produce large quantities of IgM.