Q:1 The substance which is neither absorbed nor secreted in the renal tubules:

1. Pakistan Society Of Chemical PathologistsDistance Learning Programme In Chemical PathologyLesson No 10renal function testsBy Surg Commodore AamirIjazMCPS, FCPS, FRCP (Edin)Professor of Pathology / Consultant Chemical PathologistBahria University Medical &Dental College / PNS SHIFA KarachiDr Lena Jaffery, FCPS (Chem path)Instructor AKU Karachi

2. Albumin Creatinine Inulin Paraminohippuric acid Urea Q:1The substance which is neither absorbed nor secreted in the renal tubules: Best answer: c. Inulin

3. Inulin • Inulin is a substance which is neither absorbed nor secreted and is an exact indicator of GFR • It is not part of normal human metabolism and has to be injected externally

4. 24 hour urinary clearance of that substance Amount of that substance excreted through kidney in one minute Concentration of the substance in urine Ratio of urinary concentration of that substance to urinary creatinine Volume of plasma cleared of that substance in one minute Q:2: Renal Clearance of a substance Best answer: • e. Volume of plasma cleared of that substance • in one minute

5. Renal Clearance of a substance • Clearance of substance is defined as volume of plasma cleared of that substance in one minute (or second). • It is expressed as ml/min or ml/sec

6. Creatinine calculated by Modification of Diet in Renal Disease (MDRD) formula Creatinine clearance Serum creatinine Serum urea Urinary creatinine Q:3The test which is MOST effected by extra-renal conditions in the absence of a renal disease: Best answer: d. Serum urea

7. The test which is MOST effected by extra-renal conditions (without renal disease): • Serum Urea can go upto 60 mg/dl (10 mmol/L) due to increased protein diet • It can go upto 120 mg/dl (20 mmol/L) due to dehydration etc.

8. Q:4The test which gives the poorest indication of glomerular function is:a. Calculation of eGFRb. Creatinine clearancec. Iohexol Clearanced. Serum creatininee. Serum cystanin C Best answer: • d. Serum Creatinine

9. Q:5 The earliest marker of Acute Kidney Injury is:a. Alpha one microglobulinb. Neutrophil gelatinase-associated lipocalinc. Retinol binding proteind. Urinary osmolality gape. Urinary sodium Best answer: b. Neutrophil gelatinase-associated lipocalin

10. Neutrophil gelatinase-associated lipocalin(NGAL) NGAL is a highly predictive biomarker of acute kidney injury (AKI) It as an early marker of AKI  The sensitivity for NGAL to predict AKI is 0.815 (95 % confidence interval, 0.732-0.892) It is similar to troponin for acute myocardial infarction There is evidence for the role of NGAL measurements in a variety of clinical situations leading to AKI e.g. contrast-induced nephropathy, AKI after cardiac surgery or kidney transplantation and AKI in the critical care setting

11. Q:6A patient with severe Acute Kidney Injury (AKI) faces an abrupt decline in renal function. According to one of the staging systems which of the following is the first stage of this failure:a. ESRDb. Failurec. Injuryd. Losse. Risk Best answer: e. Risk

12. Acute Kidney Injury (AKI) The term acute kidney injury (AKI) is used to represent the full spectrum of renal injury, from mild to severe, with the latter having increased likelihood for unfavorable outcomes e.g. loss of function and End Stage Renal Disease (ESRD). (AKI Network 2007)

13. Definition of AKI An abrupt (within 48 hours) reduction in kidney function i.e. an absolute increase in serum creatinine of ≥ 26.4 μmol/L (or 0.3 mg/dL ); a percentage increase in serum creatinine of 50% or more (1.5-fold from baseline); or a reduction in urine output (documented oliguria of less than 0.5 mL/kg per hour for more than 6 hours)

14. RIFLE Criteria of AKI

15. RIFLE Criteria of AKI (cont) Three stages of acute injury : Risk Injury Failure Two outcome measures : Loss of renal function ESRD

16. Q:7Latest definition of Chronic Kidney Disease (CKD) includes presence of kidney damage or decreased kidney function for three or more months. Which of the following is NOT included in the list of indicators of Kidney Damage:a. Albuminuriab. Decreased GFRc. Imaging abnormalitiesd. Kidney transplantatione. Urinary sediment abnormalities Best answer: b. Decreased GFR

17. Chronic Kidney Disease (CKD) The term CKD has replaced all the previously used vague terms like Chronic Renal Failure, “chronic renal insufficiency,” “pre-dialysis,” and “pre-endstage renal disease. A conceptual change in the disease definition. Now NO consideration of the cause of the failure in definition.

18. Definition of CKD The definition is based on 3 components: An anatomical or structural component (markers of kidney damage, including albuminuria, A functional component (based on GFR) A temporal component at least 3 months’ duration of structural and/or functional alterations.

19. Guidelines for CKD K DOQI : The National Kidney Foundation Kidney Disease Outcomes Quality Initiative (NKF KDOQI) ™ provides evidence-based clinical practice guidelines for all stages of chronic kidney disease (CKD) and related complications KDIGO: Kidney Disease Improving Global Outcomes. This guidelines adds Albuminuria with GFR for staging of CKD.

20. Kidney Damage Kidney damage includes pathologic abnormalities in the native or transplanted kidney. Kidney damage is identified in most cases by the presence of one of the following clinical markers : 1. Albuminuria − In clinical practice, albuminuria is the most frequently assessed marker of kidney damage.Albumin-to-creatinineratio (ACR) in an untimed "spot" urine is the best method to measure it.

21. Kidney Damage (cont) 2. Urinary sediment abnormalities − Urinary sediment abnormalities such as red or white blood cell casts may indicate the presence of glomerular injury or tubular inflammation. 3. Imaging abnormalities − Kidney damage may be detected by the presence of imaging abnormalities such as polycystic kidneys, hydronephrosis, and small and echogenic kidneys. Pathologic abnormalities − A kidney biopsy may reveal evidence for glomerular, vascular, or tubulointerstitial disease. Kidney transplantation − Patients with a history of kidney transplantation are assumed to have kidney damage whether or not they have documented abnormalities on kidney biopsy or markers of kidney damage. .

22. Kidney Damage (cont) 4. Pathologic abnormalities − A kidney biopsy may reveal evidence for glomerular, vascular, or tubulointerstitial disease. 5. Kidney transplantation − Patients with a history of kidney transplantation are assumed to have kidney damage whether or not they have documented abnormalities on kidney biopsy or markers of kidney damage. .

23. Decreased GFR GFR is generally considered to be the best index of overall kidney function Declining GFR is the hallmark of progressive kidney disease. Measured GFR varies in normal individuals by : age sex dietary protein intake Race-ethnicity Threshold defining a decreased GFR is less than 60 mL/min per 1.73 m2 Kidney failure is defined as a GFR <15 mL/min per 1.73 m2 or treatment by dialysis

24. Q:8A 56 years male has following Renal Profile:• Urea 23.6mmol/L (142 mg/dl)• GFR 52.3 mL/min per 1.73 m2• Albumin Creatinine Ratio: 22.4 mg/mmol of creatinineAccording to the latest criteria of CKD staging, the most appropriate stage of the patient is:a. G1 and A1b. G2 and A1c. G3a and A2d. G3b and A2e. G4 and A3 Best answer: c. G3a and A2

25. Staging of CKD The purpose of CKD staging is to: Guide management Risk stratification for progression and complications of CKD. Select appropriate treatments Frequency of monitoring Patient education

26. Staging of CKD (cont) In patients who are diagnosed with CKD using the criteria described above, staging of the CKD is done according to : Cause of disease Six categories of GFR (G stages) Three categories of albuminuria (A stages) (Based on KDOQI and KDIGO guidelines)

27. Staging of CKD (cont) Cause of diseasee.g.: Diabetes Mellitus Drug toxicity Auto-immune diseases Urinary tract obstruction, Kidney transplantation

28. Staging of CKD (cont) GFR — The GFR (G-stages) G1 − GFR >90 mL/min per 1.73 m2 G2 − GFR 60 to 89 mL/min per 1.73 m2 G3a − GFR 45 to 59 mL/min per 1.73 m2 G3b − GFR 30 to 44 mL/min per 1.73 m2 G4 − GFR 15 to 29 mL/min per 1.73 m2 G5 − GFR <15 mL/min per 1.73 m2 or treatment by dialysis

29. Staging of CKD (cont) Albuminuria — The three albuminuria stages are: A1 − ACR < (<3.4 mg/mmol(30 mg/g ) (Normal) A2 − ACR 3.4 to 34.0 mg/mmol(30 to 299 mg/g) (Microalbuminuria) A3 − ACR ≥34.0 mg/mmol(300 mg/g ) (Macroalbuminuria)

30. Q 11:Jeffe`s reaction is used for estimation of creatinine for more than 130 years now but there have been problems with its specificity. a. What is the most important development in analysis of creatinine which has led to marked improvement in its specificity?b. Name THREE enzymaticmethods of creatinine estimation.c. Name Definite Method of Creatinine estimation.

31. Suggested Answer to Q.9 a What is the most important development in analysis of creatinine which has led to marked improvement in its specificity?  Kinetic method of assay

32. Suggested Answer to Q.9 b Name THREE enzymatic methods of creatinine estimation.  Creatininase (creatinineamidohydrolase) Creatininase & creatinase Creatininedeaminase (creatinineiminohydrolase)

33. Suggested Answer to Q.9 c Name Definite Method of Creatinine estimation. Isotope- dilution mass spectrometry (ID-MS)

34. Q 10:You are working in a tertiary care Pakistani hospital. Your Head of the Department is not a Chemical Pathologist. He is fed-up of getting complaints regarding Creatinine Clearance test. He wants you to give him a presentation regarding this investigation. Please address following questions for this presentation:a. Which renal function is assessed by this test?b. Name other methods which are used for assessment of this function of kidneys.C. What are the problems associated with Creatinine Clearance? d. Can we dispense with Creatinine Clearance test by using some calculated parameters based on serum creatinine? Name two such parameters for adults and one for paediatric population.e. A recently developed test has been suggested to replace Creatinine Clearance. Write two lines about this test (now available in Pakistan, too).

35. Suggested Answer to Q.10 a Which renal function is assessed by this test? Glomerular Function Rate.

36. Suggested Answer to Q.10 b Name other methods which are used for assessment of this function of kidneys.  (Please see following slides) .

37. Glomerular filtration rate(GFR describes the flow rate of filtered fluid through the kidney GFR is a measure of the efficiency with which the kidneys remove waste products from the blood stream Normal GFR is 80-120ml/min Measuring Renal Function

38. A number of methods are used to measure GFR Most involve the kidney’s ability to clear either an exogenous or endogenous marker Estimation of GFR

39. GFR can be calculated by measuring any chemical that has a steady level in the blood, and is freely filtered but neither reabsorbed nor secreted by the kidneys The rate therefore measured is the quantity of the substance in the urine that originated from a calculable volume of blood Calculating GFR

40. For a reliable plasma measurement substance must have reached steady state concentration For a reliable urine collection urine flow must be adequate, collection period long enough and complete bladder emptying achieved Accurate plasma and urine measurement

41. Exogenous Endogenous Markers of GFR

42. Freely filterable at the glomerular barrier Not reabsorbed by the tubules Not secreted by the tubules Present at a stable plasma concentration Criteria for GFR Markers

43. Non radioactive Inulin Iohexol Iodoacetate Diethylenetriaminepentaacetic acid Radioactive Tc-diethylenetriaminepentaacetic acid Cr-ethylenediaminetetraacetic acid I-hippuran I-iodothalamate Exogenous Markers

44. Its use is for monitoring of slowly progressing nephropathies Also to detemine a GFR to set a benchmark against which to monitor deterioration in GFR using an endogenous marker Exogenous Markers

45. Gold standard Metabolically inert sugar Neither reabsorbed nor secreted Provides good estimation of GFR Time consuming Poor specificity of analysis Extrarenal clearance =0.83 ml/min/10kg Inulin Clearance

46. Renal tubular secretion or reabsorption must not contribute to its excretion Plasma protein binding of radionuclide should be negligible Complete bladder emptying essential Measurement of GFR by Urinary Clearance of a Radionuclide

47. Fasting subject is required to drink 500ml of water 1 hour before Takes 200 ml of water every half hour until the end of the study Supine throughout Intravenous loading dose of marker Constant infusion of a given quantity per minute for 3 hour Collect a blood sample and timed urine samples Constant Infusion Technique

48. Fasting subject to drink 5ooml of water 1 hour before Supine throughout Single marker dose is infused at a constant rate over 5 minutes-peristaltic pump Line flushed with saline Venous blood samples are collected at intervals 120,180,240 min Plasma disappearance curve is measured Single Bolus Injection

49. Creatinine Urea Beta2-Microglobulin Retinol-binding protein Alpha1-Microglobulin Cystatin C Endogenous Markers

50. No injection required Only a single blood sample needed Simplifies the procedure for the patient, clinician and laboratory These proteins are entirely eliminated from the circulation Advantages