RENAL FUNCTION ASSESSMENT ASSESSMENT OF GLOMERULAR FUNCTION ASSESSMENT OF TUBULAR FUNCTION

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1 Measured GFR (mgfr mgfr) and Estimated t GFR (egfr egfr) R. Mohammadi Biochemist (Ph.D.) Faculty member of Medical Faculty

2 RENAL FUNCTION ASSESSMENT ASSESSMENT OF GLOMERULAR FUNCTION ASSESSMENT OF TUBULAR FUNCTION

3 ASSESSMENT OF GLOMERULAR FUNCTION NONPROTEIN NITROGEN DETERMINATION Serum Urea Serum Creatinine DETERMINATION OF GLOMERULAR FILTRATION RATE Creatinine Clearance Estimated GFR (egfr) Cystatin C ASSESSMENT GLOMERULAR PERMABILITY Proteinuria Hematuria

4 NONPROTEIN NITROGEN (NPN) UREA (BUN) CREATININE URIC ACID AMMONIA AMINO ACIDS

5 SERUM UREA Produce During Catabolism of Amino Acids In Liver Excreted by Kidneys into Urine

6 UREMIA PRERENAL High Protein Intake, Dehydratation, Decreased Renal Perfusion (Shock, Hemorrhage, Congestive Heart Failure) Drugs (Corticosteoroides, Tetracycline) RENAL Glumerular Disease, Tubular Disease, Renal Failure POSTRENAL Nephrolithiasis, Genitourinary Tumors, Prostate Enlargement

7 BLOOD UREA NITROGEN (BUN) O = C NH 2 NH 2 UREA = 60 BUN = 28 UREA 60 = = 2.14 BUN 28 UREA = BUN X 2.14 BUN = UREA 2.14

8 UREA DETERMINATION CHEMICAL (NONENZYMATIC) METHODS Diacethyl Monoxime Urea + Diacethyl Yellow Diazine Addition of Thiosemicarbazide Pink Color Thosemicarbazide & Fe 2+ O-Phethaldehyde Stability & Increased Intensity

9 SAMPLE Specimens Serum, Urine Urine Diacetyhl Monoxime Method Increasing by Dietary Proteins & Activity Inhibition of Urease by Flouride Interference by Lipidemia, Hemolysis & Icterus Urea Has Relative Stability

10 ENZYMATIC (INDIRECT) METHODS Urea + H 2 O H 2 CO 3 + NH + 4 Nesslerization NH 4+ + Potassium Iodide + Mercury Iodide Yellow-Pink Complex Berthelot Nitroprusside NH 4+ + NaOCL + Phenol Indophenol o Indicator Dye Potentiometry Glutamate Dehydrogenase NH 4+ + α-kg + NADH + H + Glutamate + NAD + + H 2 O

11 CV% OF EQAP : Urea Kit Pa-A PA-M Zi-A Zi-M Ma-A Ma-M El-A Bi-A Ro-A Average EQAP CV% Allowable CV% CCV% Indian CCV%

12 SERUM CREATININE It Is Produced in Muscles and Is Excreted by Kidneys Nonrenal Factors Such as Dehydratation & Protein Catabolism Have No Significant Effect on Serum Creatinine Values But Is Affected By Muscle Mass, Sex, Race, Diet, and Tubular Excretion

13 CREATINIE DETERMINATION CHEMICAL (NONENZYMATIC) METHODS Alkaine Picric Reaction (Jaffe Method) 1) Interference with Proteins, Glucose, Ascorbate, Pyruvate, Acetoacetate, Acetone, Cephalosporins p 2) Using Ion Exchange Resins, Oxidation, Extraction, Acid Blank, Kinetic

14 ENZYMATIC METHODS Creatinase & Creatine Kinase Creatininase Creatinine + H 2 O Creatine CK Creatine + ATP Creatine Phosphate + ADP Pyruvate Kinase PEP + ADP Pyruvate + ATP LDH Pyruvate + NADH + H + Lactate t + NAD +

15 SAMPLE Fasting is not Necessary Increased by Activity Stable Decreased in Urine with ph less than 4.9 Hemolytic & Icterus Serums Are not Recommended

16 CV% OF EQAP : Creatinine Kit Pa-A PA-M Zi-A Zi-M Ma-A Ma-M El-A Bi-A Ro-A Average EQAP CV% Allowable CV% CCV% Indian CCV%

17 For Evaluation of Renal Diseases, Serum Urea & Creatinine Have Low Sensitivity Low Specificity

18 Serum Urea Nitrogen Serum Creatinine Normal Value Prerenal Increasesd Renal Normal Postrenal Increasesd

19 GLOMERULAR FILTRATION RATE (GFR) Is for Evaluation of Functional Nephron Mass Is for Monitoring of Renal Disease Is for Drug Dose Adjusment Is Calculated ated from Clearance a U S (mg/dl) x V U (ml/min) x 1.73 P S (mg/dl) x A

20 Criteria for Ideal Substance in Clearance Determination Constant Serum Concentration Ready Pass through Glomerular Filtration Barrier Neither Secreted Nor Reabsorbed Easy Measurement

21 INULIN CLEARANCE Inulin Is A Fructosan Inulin Pass Readily through Glomerular Barrier And Has No Secretion & Absorption Is Reference Method Needs Continuous Injection

22 CREATININE CLEARANCE Creatinine production Is Relatively Constant (with 15% Daily Variation) Creatinine Has Tubular Secretion Overstimation Is Increase When GFR Is Low Is Inhibited by Salicylate, Cimetidine, Trimethoprim Needs 24h Urine Collection

23 UREA CLEARANCE Urea production Is Not Relative Constant Urea Has Tubular Absorption Understimation Decrease in GFR Shock, Hemorrhage, Congestive Heart Failure Drugs Corticosteoroides, t id Tetracycline Needs 24h Urine Collection

24 Estimated GFR (egfr) 24h Urine Collection is not needed Is Based on Serum Creatinine Measurment and Correction for Weight, Age, Sex, and probably Race, Body Surface Area (BSA), or Renal Disease

25 Cockcroft Gault (GC) Equation Was Published in 1976 by Cockcroft and Gault Is Based on Serum Creatinine Measurment and Correction for Weight, Age, and Sex egfr = (140 age) x Weight 72 x Serum Creatinine Is Corrected for Female by multiplying 0.85

26 Modification of Diet in Renal Disease (MDRD) Equation Was Developed in 1999 by using patients who had CKD identified by elevated serum creatinine levels Is Based on Serum Creatinine Measurment and Correction for Weight, Age, and Sex egfr = 186 x Serum Creatinine x age x F F Is for Female

27 MDRD Equation In 2005, the Australasian Creatinine Consensus Working Group recommended that an egfr based on the abbreviated MDRD formula be automatically calculated for every request for plasma creatinine in people over 18 years

28 Chronic Kidney Disease Epidemiology Collaboration (CKD-EPI) Was Developed in 2009 by CKD- Epidemiology Collaboration group and intended to be more generalizable across various clinical settings than MDRD equation Weight, diabetes, and transplant were considered as potential variables, but the final equation uses the same variables as the MDRD equation

29 Chronic Kidney Disease Epidemiology Collaboration (CKD-EPI) Developed to match the accuracy of the MDRD equation at GFR < 60 ml/min/1.73m2 and to offer greater accuracy at higher GFR, minimizing the over-diagnosis of CKD with the MDRD equation

30 CKD-EPI Serum Creatinine egfr = a x ( ) c x (0.933) age b

31 Study In Spain Was Made on 84 Nondialyzed Patients t with CKD in the Stage 4 or 5 Results Correlation Mehod (ml/min/1.73m 2 ) coefficient Creatinine Clearance 13.5 ± Classic CG 14.2 ± Corrected CG 12 ± MDRD 12.1 ± In corrected CG, 0.84 is used as correction factor to compensate for the effect of tubular secretion of creatinine and make it closer to glomerular filtration Classic CG equation is better than MDRD equation for estimating GFR in patients with advanced CKD

32 Study In China Was Made on 7832 General Population Mehod MDRD Equation CG Equation Results (ml/min/1.73m 2 ) 78.6 ± ± 21.6 MDRD mean was higher than CG mean This difference is higher in older

33 Study In Pakistan Was Made on 369 outpatients ti t and inpatients t over 20 years Method CG Equation MDRD Equation Correlation coefficient with creatinine clearance when serum creatinine<1.5 mg/dl Correlation coefficient with creatinine clearance when serum creatinine>1.5 mg/dl

34 Study In Iran Was Made on 559 Outpatients Correlation Coefficient with Creatinine Clearance Equation CG MDRD All Ages years years > 60 years CKD-EPI

35 Limitations of egfr Is Not Suitable for GFR > 60 ml/min and < 15 ml/min Is Not Suitable for Children and Older Is Not Suitable for Vegetarians and Who Have Changed Body Mass Is affected by factors affecting on serum creatinine, creatinine excretion, and creatinine measurment

36 CYSTATIN C Is Low Molecular Protein With 12.8 kda and pi 9.2 Is Synthesized By All Nucleated Cells Is Readily Filtrated Its Serum Concentration Depends on Glomerular Filtration and Is Not affected by Diet, Muscle Mass, Sex, Age, and Nonrenal Conditions and Diseases Has More Sensitivity for Early Stage of Renal Disease and in Children and Older Is Not Affected by Interfering Substances

Creatinine (serum, plasma)

Creatinine (serum, plasma) 1 Name and description of analyte 1.1 Name of analyte Creatinine 1.2 Alternative names None 1.3 Description of analyte Creatinine is a heterocyclic nitrogenous compound (IUPAC