Kidney Function Test: Kidney function test are normally performed to assess renal function. These are simply estimated by using a blood sample or/and urine analysis. In several medical conditions such as diabetes as well as in elderly persons, there is a need to estimate or monitor the renal function test. The following are describing the various type of kidney functions test.
Clearance Tests
Estimation of the rate of clearance for the substance which is already present in the blood is mostly preferred for the assessment of kidney function. There are two compounds namely urea and creatinine that are present in blood as well as in urine and can be used for assessment of kidney function. A decrease in the concentration of these compounds in urine reflected the high concentration of these compounds indicates a renal problem.
The rate of creatinine clearance is 145 ml/min which is marginally higher than the glomerular filtration rate (125 ml/min) because creatinine is secreted by the renal tubule. While the clearance rate for the area is 75 ml/min while is comparatively lower than GFR due to being partially reabsorbed by the renal tubules. The rate of creatinine production and elimination is equal i.e. 1: 1 ratio, so any fluctuation/difference in the reading can be used for interpretation and conclusion of results Creatinine estimation is a widely used laboratory test for assessment or detection of renal impairment. This test is useful for the early detection of impairment before the clinical manifestation likely to produce.
Urea Clearance Test/Blood Urea Nitrogen
Urea Nitrogen is the end product of protein metabolism and its rate of clearance is lesser than GFR due to its partial reabsorbed by renal tubules. Further urea clearance is also influenced by the protein contents of the diet. Due to this reason, urea clearance is not much sensitive than creatinine clearance for assessing kidney function. The normal range of urea clearance is 12 to 2o gm/24 hours in urine. Lower values of urea clearance indicate the insufficient concentration of protein in the diet or renal problem. As such the urea clearance fall below the level of 50% of normal then only the blood urea level is found to detect thus the creatinine clearance is a better indicator for the assessment of renal function.
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