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SYNOPSIS OF DISSERTATION Dr. MADHURI. M.C DEPT OF BIOCHEMISTRY ST JOHN’S MEDICAL COLLEGE BANGALORE 1 RAJIV GANDHI UNIVERSITY OF HEALTH SCIENCES, BANGALORE KARNATAKA. ANNEXURE II PROFORMA FOR REGISTRATION OF SUBJECTS FOR DISSERTATION 1 NAME AND ADDRESS OF THE CANDIDATE DR. MADHURI.M.C DEPARTMENT OF BIOCHEMISTRY ST. JOHN’S MEDICAL COLLEGE JOHNNAGAR, SARJAPUR ROAD, BANGALORE-560034, INDIA 2 NAME OF THE INSTITUTION ST. JOHN’S MEDICAL COLLEGE JOHNNAGAR, SARJAPUR ROAD, BANGALORE-560034, INDIA 3 COURSE OF STUDY AND SUBJECT MD BIOCHEMISTRY 4 DATE OF ADMISSION 9-7-2013 5 TITLE OF THE TOPIC “A comparative study of Estimated GFR versus measured Creatinine Clearance in reference population of Indian Origin”. 2 6. Brief resume of the intended work: 6.1 NEED FOR THE STUDY The Cockcroft-Gault (CG), Modification of Diet in Renal Disease (MDRD) and CKD-EPI Chronic Kidney Disease Epidemiology formulae have not been validated in Indian population. There is limited literature available on the performance of estimated GFR (eGFR) formulas in Indian population based on age group. Hence, this study is aimed to compare the diagnostic performance of eGFR formulas, and measured creatinine clearance in reference population of Indian origin. 6.2 REVIEW OF LITERATURE The Glomerular filtration rate (GFR) is considered to be the most reliable measure of the functional capacity of the kidneys and is often thought of as indicative of the number of functioning nephrons. As a physiological measurement, it has proved to be the most sensitive and specific marker of changes in overall renal function. 1 A low or decreasing GFR is a good index of chronic kidney disease. Since the total kidney GFR is equal to the sum of the filtration rates in each of the functioning nephrons, the total GFR can be used as an index of functioning renal mass.2 A decrease in GFR precedes kidney failure in all forms of progressive kidney disease. Monitoring changes in GFR can delineate progression of kidney disease. The level of GFR is a strong predictor of the time to onset of kidney failure as well as the risk of complications of chronic kidney disease. Additionally, estimation of GFR in clinical practice allows proper dosing of drugs excreted by glomerular filtration to avoid potential drug toxicity. Glomerular filtration rate cannot be measured directly. If a substance in stable concentration in the plasma is physiologically inert, freely filtered at the glomerulus, and neither secreted, reabsorbed, synthesized, nor metabolized by the kidney, the amount of that substance filtered at the glomerulus is equal to the amount excreted in the urine. The fructose polysaccharide inulin has each of the above properties and has long been considered an ideal substance to estimate GFR. The amount of inulin filtered at the glomerulus equals the GFR multiplied by the plasma inulin concentration: GFR × Pin. The amount of excreted inulin equals the urine inulin concentration (Uin) multiplied by the urine flow rate (V, volume excreted per unit time). Since filtered inulin = excreted inulin: (1) GFR×Pin=Uin×V 3 (2) GFR= Uin×V Pin The term (Uin × V)/Pin is defined as the clearance of inulin and is an accurate estimate of GFR. The inulin clearance, in mL/min, refers to that volume of plasma per unit time that is cleared of inulin by renal excretion. Inulin clearance is widely regarded as the gold standard for measuring glomerular filtration rate. Inulin clearance measurements in healthy, hydrated young adults (adjusted to a standard body surface area of 1.73 m2) have mean values of 127 mL/min/1.73 m2 in men and 118 mL/min/1.73 m2 in women with a standard deviation of approximately 20 mL/min/1.73 m2. 3Among adults, numerous studies suggest that glomerular filtration rate is lower at older ages. After age 20 to 30 years, GFR decreases by approximately 1.0 mL/min/1.73 m2 per year with substantial interindividual variation even among “healthy” individuals.4,5 Whether this average decline with aging is optimal in terms of predicting the risk of complications of decreased kidney function and mortality is unknown. Rationale for Alternative Measures The classic method of inulin clearance requires an intravenous infusion and timed urine collections over a period of several hours making it costly and cumbersome. As a result a number of alternative measures for estimating GFR have been devised. The urinary clearance of exogenous radioactive markers (125I-iothalamate and 99mTcDTPA), provide excellent measures of GFR6 but are not readily available. The most widely used measures of GFR in clinical practice are based on the 24-hour creatinine clearance or serum creatinine concentration. The use of the serum level of creatinine as an index of GFR rests on three important assumptions: (a) creatinine is an ideal filtration marker whose clearance approximates GFR; (b) creatinine excretion rate is constant among individuals and over time; and (c) measurement of serum creatinine is accurate and reproducible across clinical laboratories. Creatinine excretion by the kidney: Creatinine is freely filtered by the glomerulus, but is also secreted by the proximal tubule. Hence, the amount of creatinine excreted in the urine is the composite of both the filtered and secreted creatinine and can be represented by the following equation: (3) UCr×V=GFR×PCr+TSCr Where TSCr is the rate of tubular creatinine secretion, Dividing by PCr: (4) CCr=GFR+CTSCr Where CTSCr is the clearance of creatinine due to tubular secretion thus, creatinine clearance systematically overestimates GFR. 4 Factors other than the level of GFR can also influence creatinine secretion. Creatinine secretion is inhibited by some common medications, for example, cimetidine and trimethoprim. Creatinine metabolism: The urinary creatinine excretion represents the difference between creatinine generation in the body (GCr) and extra-renal creatinine elimination (ECr): (5) UCr×V=GCr-ECr Substituting into equation 3 and re-arranging for PCr yields the following: (6) PCr = TSCr-ECr GFR It can therefore be inferred that the relationship between serum creatinine and GFR is affected by the generation and extra-renal excretion of creatinine, as well as the filtration and secretion of creatinine by the kidney. Creatinine is mainly derived from the metabolism of creatine in muscle, and its generation is proportional to the total muscle mass. As a result, mean creatinine generation is higher in men than in women, in younger than in older individuals, and in blacks than in whites. This leads to differences in serum creatinine concentration according to age, gender, and race, even after adjusting for GFR. Creatinine measurement: The normal levels of creatinine in the blood are approximately 0.8 to 1.3 milligrams (mg) per deciliter (dL) in adult males and 0.6 to 1.0 milligrams per deciliter in adult females. The traditional assay for measurement of creatinine is the alkaline picrate (Jaffe) method, which detects non-creatinine chromogens in serum (approximately 0.2 mg/dL), as well as creatinine. Urine does not contain non-creatinine chromogens, nor are these compounds retained in chronic kidney disease. Thus, historically, measured creatinine clearance has systematically underestimated true creatinine clearance. By coincidence, the difference between measured and true creatinine clearance is similar in magnitude to the clearance of creatinine due to tubular secretion. Hence, measured creatinine clearance has historically approximated the level of GFR. Creatinine clearance is measured by following equation: Creatinine clearance: U X V x 1.73 (ml/minute) P A U = urine creatinine (mg/dl) V = urine volume / minute i.e., Total volume 24 X 60 P = plasma / serum creatinine (mg/dl) 1.73 = Average body weight A = Body surface area (calculated from Nomogram using subject’s height and weight). 5 The Jaffe reaction, despite its non-specificity for creatinine, is still widely employed as the method of choice for creatinine testing7 due to its speed, adaptability in automated analysis, and cost-effectiveness, and is the oldest methodology continued to be used in the medical laboratory.8 In summary, serum creatinine is affected by the level of GFR and by factors independent of GFR, including age, gender, race, body size, diet, certain drugs, and laboratory analytical methods. Equation used to estimate creatinine clearance: Cockcroft-Gault equation The Cockcroft-Gault9,10 formula was developed in 1973 using data from 249 men 2 with creatinine clearance (CCr) from approximately 30 to 130 mL/m . It is not adjusted for body surface area. CCr= (140-age) x weight x 0.85 if female (72 x SCr) Where CCr is expressed in milliliters per minute, age in years, weight in kilograms, and serum creatinine (SCr) in milligrams per decilitre. Equations used to estimate GFR (eGFR): (i) Modification of Diet in Renal Disease (MDRD) equation and (ii) The Chronic Kidney Disease Epidemiology Collaboration (CKD-EPI) equation Modification of Diet in Renal Disease (MDRD) study or CKD-Epidemiology Collaboration (CKD-EPI) equations estimate GFR in ml/min per 1.73 m2 .It estimates GFR adjusted for body surface area[11,12,13]. The "4-variable MDRD," estimates GFR using four variables: serum creatinine, age, ethnicity, and gender. [14] Modification of Diet in Renal Disease (MDRD) formula, 4-variable MDRD: eGFR= 186 × (SCr) −1.154 × Age−0.20 3× [0.742 if female] = ml/min/1.73m2 Serum creatinine (SCr) is expressed in milligrams per decilitre (mg/dl) The CKD-EPI formulae For ‘non-black females’: If Serum creatinine ≤ 0.7 mg/dl o eGFR= 144 × (SCr /0.7)−0.329 × 0.993Age = ml/min/1.73m2 If Serum creatinine > 0.7 mg/dl o eGFR=144 × (SCr /0.7)−1.209×0.993Age = ml/min/1.73m2 6 For ‘non-black males’: If Serum creatinine ≤0.9 mg/dl o eGFR=141 × (SCr /0.9)−0.411 × 0.993Age = ml/min/1.73m2 If Serum creatinine >0.9 mg/dl o eGFR=141 × (SCr /0.9)−1.209 × 0.993Age = ml/min/1.73m2 6.3 OBJECTIVES OF THE STUDY 1. To estimate and compare the (eGFR) estimated GFR using (MDRD) Modification of Diet in Renal Disease, (CKD-EPI) The Chronic Kidney Disease Epidemiology Collaboration formulas and estimated creatinine clearance using Cockcroft- Gault (CG) equation and measured 24hrs creatinine clearance. 2. To quantify the discrepancy, if any, in Glomerular Filtration Rate (GFR) estimated by MDRD and CKD-EPI formulae and estimated creatinine clearance using (CG) with measured 24 hrs urine Creatinine Clearance (Cr Cl). 7. Material and methods 7.1 SOURCE OF DATA The study will be conducted on health care workers, volunteers or kidney donors attending Out Patient Department in St. Johns Medical College Hospital, Bangalore between December 2013- December 2015 will be included for the study. An informed consent will be taken from them. INCLUSION CRITERIA Adult male and female health care workers, volunteers or kidney donors aged between 20 – 30 years of age. EXCLUSION CRITERIA Age < 20 years and > 30 years. Patients with history of chronic kidney disease. Patients with history of Hypertension and Diabetes. Patients with acute renal failure or impairment. Pregnancy. 7 Patients on medication with cephalosporin, aminoglycoside antibiotics, flucytosine, cisplatin, cimetidine, antacids, trimethoprim and diuretics. Patients on dialysis. 7.2 METHOD OF COLLECTION OF DATA 7.2 a. Method of data collection: Informed consent will be obtained from all the subjects who fulfill the inclusion criteria for the study. The following demographic data will be taken from patient or from case records. 1. 2. 3. 4. Age Sex Clinical history Drug history –cephalosporin and aminoglycoside antibiotics, flucytosine, cisplatin, cimetidine and trimethoprim. 5. Medical history – Diabetes mellitus, hypertension, chronic renal diseases, renal failure, and history of dialysis. 6. Anthropometric measurements – height, weight, BMI 7. Diet history 7.2.b. Method of sample collection: After taking informed consent from the volunteers or kidney donors, about 5 ml of whole blood sample will be collected under aseptic precautions. This will be allowed to clot, and then centrifuged for 10 minutes at 3000 rpm. The serum will be separated and analyzed for serum creatinine levels with modified Jaffe reaction. For 24hrs urine sample the subjects will be provided a can for collection of urine and will be given instructions for collecting 24hrs urine sample for urine creatinine estimation by modified Jaffe reaction. 7.2. c. Sample size: 50 Based on the study[15] it was observed that the mean value for 24hr urine creatinine clearance was 97.4 ± 31.5 (ml / min/1.73 m2) and the mean GFR by Cock-Croft Gault was 109.6 ± 27.9 (ml / min/1.73 m2). In order to find a mean difference of 12 ml / min/1.73 m2 with 80% power and 5% level of significance the minimum number of subjects required will be 48. 7.2. d. Type of study: Cross-sectional study 8 7.2.e. Statistical Analysis: Descriptive statistics will be reported using mean and standard deviation (SD) for normally distributed continuous variables, otherwise median and interquartile range. Assumption of normality will be assessed, co-relation coefficient and intra-class corelation will be calculated between measured creatinine clearance (gold standard) and the other estimated GFRs under Bland – Altman plot . P- value < 5 % will be considered as statistically significant. 7.3. Does the study involve any investigation or any intervention to be conducted on patients or other humans or animals? If so, please describe briefly. The study requires the following investigations to be done on patients. (a) Serum creatinine (b) Urinary creatinine (c) Creatinine clearance Blood samples will be collected from the subjects by venipuncture observing all safety and aseptic precautions. Blood samples for serum creatinine estimation will be collected in red capped Vacutainer tubes or serum separator tubes and sent for analysis. 24hrs urine sample- For this the patient is asked to collect 24 hours' worth of urine in a special container and submit it for analysis. The serum and urinary creatinine readings will be utilized to measure creatinine clearance. 7.4 Has ethical clearance been obtained from your institution in case of 7.3? YES 8. List of References 1.Burtis C A, Ashwood E R, Bruns D E. Tietz Textbook of Clinical Chemistry and Molecular diagnostics. Chapter 24, Kidney Function Tests.4th edition. Elsevier; 2006:1920-1925. 2. Rose BD: Chapter 3: Renal Circulation and Glomerular Filtration Rate: Clinical Physiology of Acid-Base and Electrolyte Disorders. New York, NY, McGraw Hill, 1984. 3. Smith HW: Comparative physiology of the kidney, in Smith HW (ed): The Kidney: Structure and Function in Health and Disease. New York, NY, Oxford University Press, 1951, pp 520-574. 9 4. Lindeman RD, Tobin J, Shock NW: Longitudinal studies on the rate of decline in renal function with age. J Am GeriatrSoc 33:278-285, 1985. 5. Perrone RD, Madias NE, Levey AS: Serum creatinine as an index of renal function: New insights into old concepts. ClinChem 38:1933-1953, 1992. 6.Perrone RD, Steinman TI, Beck GJ, Skibinski CI, Royal HD, Lawlor M, Hunsicker LG: Utility of radioscopic filtration markers in chronic renal insufficiency: Simultaneous comparison of 125I-iothalamate, 169Yb-DPTA, and inulin.The Modification of Diet in Renal Diseases Study. Am J Kidney Dis 16:224235, 1990. 7. Ahmed, Nessar, Clinical Biochemistry. New York: Oxford University Press. (2011). p. 72. 8. Taylor, E. Howard, Clinical Chemistry. New York: John Wiley and Sons. (1989). pp. 4, 58–62. 9. Gault MH, Longerich LL, Harnett JD, Wesolowski C: Predicting glomerular function from adjusted serum creatinine. Nephron 62:249-256, 1992. 10. Cockcroft DW, Gault MH: Prediction of creatinine clearance from serum creatinine. Nephron 16:31-41, 1976. 11. Levey AS, Coresh J, Greene T, et al. Using standardized serum creatinine values in the Modification of Diet in Renal Disease study equation for estimating glomerular filtration rate. Ann Intern Med 2006; 145:247–254. 12. Levey AS, Stevens LA, Schmid CH, et al. A new equation to estimate glomerular filtration rate. Ann Intern Med 2009; 150:604–612. 13. Phillippa K Bailey, Charles RV Tomson, Sanjay Kinra, Shah Ebrahim, KV Radhakrishna, Hannah Kuper, et al Differences in estimation of creatinine generation between renal function estimating equations in an Indian population: cross-sectional data from the Hyderabad arm of the Indian migration study BMC Nephrol. 2013; 14: 30. Published online 2013 February 4. doi: 10.1186/1471- 236914-30 14. M. Kannapiran, D. Nisha, and A. Madhusudhana Rao, Underestimation of Impaired Kidney Function with Serum Creatinine, Indian J Clin Biochem. 2010 October; 25(4): 380–384. 15. Chung BH, Yu JH, Cho HJ, Kim J-I, Moon IS, et al. (2013) Comparison of Estimating Equations for the Prediction of Glomerular Filtration Rate in Kidney Donors before and after Kidney Donation. PLoS ONE 8(4): e60720. doi:10.1371/journal.pone.0060720. 10 9. Signature of Candidate 10. Remarks of the guide 11. Name and Designation of ( in Block Letters) 11.1 Guide DR. RADHIKA KRISHNASWAMY Associate PROFESSOR DEPARTMENT OF BIOCHEMISTRY ST JOHNS MEDICAL COLEGE, BANGALORE 11.2 Signature 11.3 Head of Department Dr. ANITA R .BIJOOR PROFESSOR AND HOD DEPARTMENT OF BIOCHEMISTRY ST JOHNS MEDICAL COLEGE, BANGALORE 11.4 Signature 12. 12.1 Remarks of the Chairman and Principal 12.2 Signature 11 PATIENT INFORMATION AND CONSENT FORM “A comparative study of Estimated GFR versus measured Creatinine Clearance in reference population of Indian Origin”. Investigator: Institutional address: Dr. MADHURI.M.C St. John’s Medical College and Hospital, Sarjapur road, Koramangala, Bangalore - 560034. Introduction You are requested to take part in a research study -“A comparative study of Estimated GFR versus measured Creatinine Clearance in reference population of Indian Origin”. Serum creatinine will be measured in your blood sample, urinary creatinine in your urine sample and creatinine clearance will be estimated as a part of the study. Before agreeing to participate in this study, you will receive oral and written information about this study. Your participation in this study will be in the form of giving your blood sample and 24 hrs urine sample once during the study period. Purpose of the Study The purpose of this study is to compare and evaluate eGFR equations, estimated creatinine clearance and measured creatinine clearance. Study Procedures If you choose to participate in this study, your blood sample will be collected for estimation of serum creatinine and 24hrs urine will be collected for creatinine clearance measurement. Risks For most people, needle punctures for blood draws do not cause any serious problems. However, they may cause bleeding, bruising, discomfort, infections, and/or pain at the needle site or dizziness. Participation in the study Your taking part in the study is entirely voluntary. You may refuse to take part in the study. Questions If you have any questions regarding this study or your rights, you can contact Dr.MADHURI.M.C, Department of Biochemistry, St. John’s Medical College, Sarjapur road, Koramangala, Bangalore-560034. Ph 080-22065050 12 Confidentiality Your personal health information will be handled by the study doctor and staff in a confidential manner. The health information will be used and disclosed in accordance with the Data Privacy Statement. - The study doctor and staff will use the medical records and information created or collected during the study to conduct the study. - The data will be used for research purposes to support the scientific objectives of this study or to improve the design of future studies. - Study data that does not identify you may be published in medical journals or shared with others as part of scientific discussions. - The medical records may be held and processed on computers. You have the right to see and copy your personal health information related to the research study. However, to ensure scientific integrity of the study, you will not be able to review some of the study information until after the study has been completed. You may cancel your authorization at any time by providing written notice to the study doctor. 13 PATIENT CONSENT FORM ATTACHMENT(1) SIGNATURE PAGE To become part of this study, and to authorize use and disclosure of your personal health information, you or your legal representative must sign and date this page. By signing this page, you are confirming the following: - You have read all of the information in this Patient Information and Consent form, and you have had time to think of it. All of your questions have been answered to your satisfaction. You voluntarily agree to be part of this research study. You may refuse to participate or freely choose to stop being a part of this study at any time. You allow the study doctor to use and disclose your personal health information as described in this document. You agree that the sample can be used for any other related studies. ________________________________________ Signature of Patient ________________________ (dd/mm/yy) _________________________________________ Patients Name _______________________ Hospital Number __________________________________________ Signature of Legal Representative ________________________ (dd/mm/yy) __________________________________________ Name of Legal Representative ________________________ Relationship to Patient __________________________________________ Signature of Impartial witness ________________________ (dd/mm/yy) __________________________________________ Name of Impartial witness I hereby state that the study procedures in details were explained and all questions were fully and clearly answered to the above-mentioned participant / legally acceptable representative. _________________________________________ Name of the investigator ____________________________________________ Signature of the investigator 14 _______________________ (dd/mm/yy) PATIENT INFORMATION FORM ATTACHMENT (2) “A comparative study of Estimated GFR versus measured Creatinine Clearance in potential kidney donors and normal healthy individuals of Indian Origin.” Dr.MADHURI.M.C., P G student, Dept. of Biochemistry, SJMC 1. Name : 2. Age : years 3. Sex : Male Female 4. Weight : Height: Date of birth : 5. Hospital No : 6. Diet Department : : Vegetarian / Non- vegetarian 7. Medical history :- (please mark if yes) Hypertension Diabetes Nephrotic syndrome Dialysis Renal Failure 8. Drug history :- (please specify the drug) Cephalosporin Ciimetidine Aminoglycoside Diuretics Flucytosine Trimethoprim Cisplatin Thiazide diuretics DATE: 15