KFT or Kidney Function Test.pptx

KFT are used for evaluating kidney functions. there are several routine tests such as urea, creatinine and uric acid. Calculation of eGFR is recommended by national kidney organization whenever creatinine serum is measured.

1. Kidney Function Test Prepared by: Mohammad Reza Abdullahi Master of Medical Sciences in Biochemistry Kabul University of Medical Sciences Allied Health Faculty Medical Laboratory Technology Department

2. content Introduction Kidney function Kidney function test Urea Creatinine Uric acid Creatinine clearance eGFR Cystatin C Microalbumin Concentration test Dilution test Urinalysis References Medical Laboratory Technology Department 2

3. Introduction The kidneys are paired, bean-shaped organs located retroperitoneally on either side of the spinal column. The functional unit of the kidney is Nephron. Nephron consist of two major parts: 1) glomerulus, 2) Tubules Medical Laboratory Technology Department 3

4. Con… There are three basic renal process Glomerular filtration Small molecules pass through glomerulus and enter the proximal convoluted tubule. GFR= 125-130 ml/min Tubular reabsorption Many molecules are reabsorbed from the nephron into the capillary Tubular secretion Some substances are actively removed from peritubular capillary plasma to tubular lumen and added to tubular fluid Medical Laboratory Technology Department 4

5. Kidney Functions Elimination of Nonprotein Nitrogen compunds (urea, creatinine and uric acid) Water, electrolyte, and acid-base homeostasis Endocrine function (e.g. synthesize erythropoietin, activate Vitamin D) Metabolic function (gluconeogenesis) Medical Laboratory Technology Department 5

6. Kidney Function Test Urea Creatinine Uric acid Creatinine clearance Estimated GFR Cystatin C Beta 2 microglobulin Microalbumin Urinalysis Concentration test Dilution test test for Glomerular function test for Tubular function Medical Laboratory Technology Department 6

7. Urea Urea is waste product of protein metabolism, it synthesized in liver via urea cycle then it transported by blood to kidney to be excreted in urine. 40 – 60 % of urea is reabsorbed. Blood urea level is not specific indicator for renal dysfunction, because: Its level is affected by dietary protein Other non renal causes such as heart failure may effect on its level. High serum urea seen in: Renal insufficiency, urinary tract blockage, heart failure, dehydration, high protein diet Blood Urea Nitrogen (BUN) can be calculated from urea. (urea/2.14) Medical Laboratory Technology Department 7

8. Creatinine Muscle contains creatine phosphate, a high-energy compound for the rapid formation of adenosine triphosphate ( ATP). This reaction is catalyzed by creatine kinase ( CK). Every day, up to 20% of total muscle creatine spontaneously dehydrates to form the waste product creatinine . Creatinine remain the same in individual and is not reabsorbed. Serum creatinine levels are higher in males than in females. Medical Laboratory Technology Department 8

9. Uric acid Uric acid i s the end product of purine metabolism and excreted in urine. Only 6 % to 12% of the original filtered uric acid is finally excreted . Elevated level of uric acid in blood is one of the markers of kidney dysfunction. High blood uric acid occurs in: gout, renal failure, leukemia, starvation… Medical Laboratory Technology Department 9

10. Creatinine clearance Clearance is defined as the volume of blood or plasma completely cleared of a substance per unit time . Creatinine clearance is derived by mathematically relating the serum creatinine concentration to the urine creatinine concentration excreted during a period of time, usually 24 hours. Crcl = Medical Laboratory Technology Department 10

11. eGFR The National Kidney Foundation recommends that estimated GFR ( eGFR ) be calculated each time a serum creatinine level is reported. eGFR does not require urine sample, so, it should be used more often than traditional creatinine clearance and result in earlier detection of chronic kidney disease (CKD ). There are a number of formulas that can be used to estimate GFR on the basis of serum creatinine levels . Cockcroft-Gault Formula Modification of Diet in Renal Disease Formula CKD-EPI Formula Medical Laboratory Technology Department 11

12. Cystatin C Cystatin C is a low-molecular-weight protein produced at a steady rate by most body tissues. It is freely filtered by the glomerulus, reabsorbed, and catabolized by the proximal tubule. Levels of cystatin C rise more quickly than creatinine levels in acute renal failure. Plasma concentrations appear to be unaffected by diet, gender, race , age , and muscle mass . A rise in cystatin C is often detectable before there is a measureable decrease in the GFR or increase in creatinine. Medical Laboratory Technology Department 12

13. Microalbumin Urine microalbumin measurement is important in the management of patients with diabetes mellitus , who are at serious risk for developing nephropathy over their lifetime. Excretion of 30 to 300 mg of albumin in a 24h urine sample is called microalbuminuria and it is measured using nephelometry or immunoturbidimetry techniques. Medical Laboratory Technology Department 13

14. Concentration Test The patient is allowed no food or water after a meal at 6 PM. The next day at 7 AM, the bladder is emptied and specimen is discarded. A second specimen is collected at 8 AM and the specific gravity is measured . If the specific gravity is more than 1.022, the patient has adequate renal function. Medical Laboratory Technology Department 14

15. Dilution Test The patient is not allowed to drink any water after midnight . Bladder is emptied at 7 AM and a water load is given ( 1200 mL over the next 30 minutes ). Hourly urine samples are collected for the next 4 hours separately. Volume, specific gravity and osmolality of each sample are measured . A normal person will excrete almost all the water load within 4 hours and the specific gravity of at least one sample should fall to 1.003 Medical Laboratory Technology Department 15

16. Urinalysis Urinalysis (UA) permits a detailed, in-depth assessment of renal status with an easily obtained specimen . UA also serves as a quick indicator of an individual’s glucose status and hepatic–biliary function . Routine UA includes assessment of physical characteristics, chemical analyses , and a microscopic examination of the sediment. First morning specimen of urine is preferred. Medical Laboratory Technology Department 16

17. Physical characteristics Medical Laboratory Technology Department 17

18. Chemical Analysis Medical Laboratory Technology Department 18

19. Microscopic examination Medical Laboratory Technology Department 19

20. References Clinical chemistry : principles, techniques, and correlations /[edited by] Michael L. Bishop , Edward P. Fody , Larry E. Schoeff .—8th ed . TIETZ FUNDAMENTALS OF CLINICAL CHEMISTRY /[edited by] Carl A. Burtis , David E. Bruns - 7 th edition Textbook of Biochemistry for Medical Students/ [edited by] DM Vasudevan, Sreekumari S, Kannan Vaidyanathan- 7th ed. Medical Laboratory Technology Department 20

21. Thanks For your attention Medical Laboratory Technology Department 21