Key to Mock TOACS

Station No 1 (Analytical Work) (STATIC) A scientist is working on an enzyme method with NADH as the indicator enzyme. Necessary Data: The transmittance of his solution of NADH: 50% Wavelength : 340 nm Light path of the cuvette : 1 cm Task:  Calculate the absorbance of this NADH solution (to two significant decimal points) and write your calculations on the answer paper Key A = 2-Log %T A = 2- Log 50 A = 2- 1.699 = 0.31

Station No 2 (Preparation of Solution) (STATIC) You are provided with 10 ml of 25% glucose stock solution  Task: How will prepare 5 ml of 1% glucose solution out of this stock solution. Key • 25%=25g /dl or 25,000mg/dl • V1C1=V2C2 • V1=? • C1=25000mg/dl • V2=5ml • C2=1000mg/dl • V1=C2V2/ C1 V1= 0.2ml

Station No 3 (Analytical Work) (STATIC)   Suppose the provided electrophoretogram is generated from a Capillary Zone Electrophoresis. Please write answers of following questions on the provided sheet: Which is the point of application of sample (Point 1 or Point 6) Name the fastest protein band (1 or 6). Name the most important driving force in this electrophoresis

Station No 3 (Analytical Work) (STATIC) Suppose this electrophoretogram is generated from a capillary zone electrophoresis (CZE) please answer following questions: Which is cathode end (Point 1 or Point 6) Which is the point of application of sample Point 1 or Point 6 Name the fastest moving protein band 1 or 6 2/21/2019

Movements of Proteins in Capillary Electrophoresis In capillary zone electrophoresis point of application is usually anode (point 1 in the example) Fastest moving band is of gamma globulin towards cathode. The reason of this migration pattern in CZE is that the main driving force in CZE is endosmosis Slowest moving protein here is albumin 2/21/2019

Station No 4 (Handling common lab problems) (STATIC)   The person sitting next to you is Lab Tech In-charge of your Routine lab. He is to show you a report of Plasma Glucose which is very high i.e. 32.2 mmo/L (580 mg/dl). Please listen to the problem he has brought to you and ask any number of questions from him Find the best course of action and then write it on the provided sheet Key Delta check should be done. First ensure proper QC results. Then retrieve previous results of the same patients. Finally call the ward or the patient about the clinical condition.

Station No 5 (Handling common lab problems) (STATIC)   The person sitting next to you is Lab Tech In-charge of your Endocrinology Lab. He is to show you Internal Quality Control data of Serum TSH. He has already analysed a batch of 42 samples for TSH. Level 1: 0.34 mIU/ml (no Westgard rule violated) Level 2: 3.2 mIU/ml (no Westgard rule violated) Level 3: 11.6 mIU/ml (+3SD Westgard rule violated) Please listen to the problem he has brought to you and write your course of action on the answer sheet. You may ask any number of questions from the technologist. Key Delta check should be done. First ensure proper QC results. Then retrieve previous results of the same patients. Finally call the ward or the patient about the clinical condition.

Station No 7 (Handling common lab problems) (STATIC)   The person sitting next to you is Lab Tech In-charge of your Lipid Lab. Please listen to his problem and suggest a solution. Problem: In your lab HDL-Cholesterol is measured by direct method while LDL-Cholesterol is measured by Friedwald`s Equation except in cases with high triglycerides which are analysed using ‘Direct LDL-C’ kits. Your technician has informed you that the stock of kits for ‘Direct HDL-C’ has finished. How will you handle this problem? Please write solution of the problem on the answer sheet. You may ask any questions from the technologist. Key Calculat HDL-C after performing LDL-C direct assay.

Station No 8 (Calculation of Derived Indices) (STATIC)   Please calculate the derived indices in the data given and write your answer on the answer sheets along with the formulae used. Creatinine Clearance Urinary Creatinine: 8.5 mmol/L Serum Creatinine : 98 µmol/L Urinary Volume: 1440 ml Please calculate Creatinine Clearance HOMA –IR Plasma Glucose Fasting: 6.8 mmol/L Serum Insulin: 18.3 mIU/L Please calculate HOMA-IR

Station No 8 (Calculation of Derived Indices) (STATIC)   Key Creatinine Clearance ml/min = 86.73 Urinary Creatinine/serum creatinine x volume of urine/1440 = 86.73 HOMA-IR Serum Insulin x Serum Glucose (F) / 22.5 = 5.5

Station No 9 (Lab Safety) (STATIC)   As a duty Registrar you have entered in your lab on a Sunday morning. Please observe your duty Lab Technologist keeping in mind the OSHA Regulations. Please write these observations on the answer sheet without talking to the technologist. Key Not using gloves No white coat Mouth pipetting Wearing open shoes etc

Station No 10 (Instrument Handling) (Interactive) Please see this instrument and answer questions of the examiner.

Station No 12  Acceptability of Random Error In a Serum ALT Assay (Around 40 U/L) Total Allowable Error (TEa) for ALT : 20% i.e. 8 U/L Allowed Swrun for ALT : 2 U/L (25% of (TEa) Allowed swday for ALT : 2 U/L (25% of (TEa) Allowed (stot) for ALT : 2.6 U/L (33% of (TEa) In this example: swrun and swday : 1.7 and 1.8 U/L which is  < 25% of TEa In this example: stot : 2.6 U/L which is  < 33% of TEa So RE is acceptable!!!!!

Station No 13 One outlier is present Difference plot is used for initial evaluation of results in comparison of method experiments

For methods that are not expected to show one-to-one agreement, for example enzyme analyses having different reaction conditions, the graph should be a “comparison plot” Displaying the test result on the y-axis versus the comparison result on the x-axis.

Station No 14 Determine upper reportable range of the Assay A sample with a true value of 500 mg/dl would, on average, be observed to be 470 mg/dL due to the systematic error from non-linearity. In addition, that value could be ±30 mg/dL due to random error, (CV: 3%; SD: 15 mg/dl) i.e., the expected value would be in the range from 440 to 500 mg/dL for a sample with a true value of 500 mg/dL. Given that the CLIA criterion for the allowable total error is 10%, which is 50 mg/dL at a level of 500 mg/dL, the errors that would be observed at 500 mg/dL could be larger than the allowable error, thus the reportable range should be restricted to a lower concentration. A sample with a true value of 400 mg/dL would, on average, be observed to be 390 mg/dL due to the systematic error from non-linearity. Addition of the random error of 24 (2SD: 12 x 2 mg/dl) gives an expected range from 366 to 414 mg/dL, which means a result might be in error by as much as 34 mg/dL. The CLIA criterion of 10% provides an allowable total error of 40 mg/dL at 400 mg/dL, thus those expected results are correct with the allowable total error (34 mg/dL < 40 mg/dL), thus the reportable range does extend to 400 mg/dL.

Station No 15 (Static) (Lab Statistics)   Task a. Name this curve b. Select the better test for screening of the disease (A or B) Key a. Receiver Operating Characteristics Curve b. Test B, as it has a larger AUC.

Station No 17 (Static) (Lab Statistics) Present Disease Absent TP FP FN TN Positive Test Negative a. TP/(TP+FN) = ? b. TN/(TN+FP) = ?