Clinical Chemistry Finals PDF

CONCEPT DIAGNOSTICS ONTARIO, CALIFORNIA 91761 USA GLUCOSE OXIDASE REAGENT SET (PHENOL FREE) GLUC...

CONCEPT DIAGNOSTICS ONTARIO, CALIFORNIA 91761 USA GLUCOSE OXIDASE REAGENT SET (PHENOL FREE) GLUCOSE (OXIDASE) REAGENT SET (PHENOL FREE) 3. Use distilled or deionized water where indicated. For the quantitative determination of total glucose in serum. STORAGE AND STABILITY INTRODUCTION Both dry reagent and standard should be stored at 2 - 8° C prior to Glucose is the major carbohydrate present in the peripheral blood. The reconstitution. The reagent may be used until the expiration date oxidation of glucose is the major source of cellular energy in the body. indicated on the package label. The reconstituted reagent should be Glucose determinations are run primarily to aid in the diagnosis and stored in an AMBER container at 2 - 8° C and is stable for thirty (30) treatment of diabetes mellitus. Elevated levels glucose levels may be days when stored as directed. The reagent should be clear and colorless. associated with pancreatitis, pituitary or thyroid dysfunction, renal failure and liver disease, whereas low glucose levels may be associated with REAGENT DETERIORATION insulinoma hypopituitaryism, neoplasms, or insulin-induced The reagent should be discarded if: hypoglycemia.1,2 1. Turbidity has occurred; turbidity may be a sign of contamination. 2. Moisture has penetrated the vial and caking has occurred. Early enzymatic methods for glucose determination involved glucose 3. The reagent fails to meet linearity claims or fails to recover control oxidase to catalyze the oxidation of glucose. Keston modified this values in the stated range. method in the early 1950's using a glucose oxidaseperoxidase enzyme system and o-dianisidine chromogen system.3 Since then various SPECIMEN COLLECTION alternative chromogen systems have been proposed. The Trinder method 1. Test specimens should be serum and free from hemolysis. replaces carcinogenic o-dianisidine with phenol plus 4aminoantipyrine.4 2. Plasma containing citrate, EDTA, heparin or oxalate as an This method is less influenced by interfering substances and does not anticoagulant may not be used. suffer from the many drawbacks of earlier methods. 3. Serum must be separated from the clot promptly since the rate of glucose decrease is approximately 7% per hour in whole blood. PRINCIPLE 4. Glucose in serum or plasma is stable for twenty-four (24) hours The enzymatic reaction sequence employed in the assay of glucose is as when stored 2 - 8° C. follows: Glucose Oxidase INTERFERING SUBSTANCES -D-Glucose + H20 + 02 ---------------------- H202 + D-Gluconic Grossly lipemic or icteric sera will cause false glucose values and require Acid the use of a serum blank. Add 0.02ml (20µl) of patient sera to 3.0 ml Peroxidase distilled water and read against a water blank. Subtract this absorbance H202 + 4-Aminoantipyrine + p-HBS -------------- Iminoquinone + from the patient test absorbance to correct for the lipemia or icterus. H20 Young et al. give a comprehensive review of drug inteferences. 5 -D-Glucose is oxidized by glucose oxidase to produce D-gluconic acid MATERIALS REQUIRED BUT NOT PROVIDED and hydrogen peroxide. The hydrogen peroxide is then oxidatively 1. Pipettes to accurately measure required volumes. coupled with 4-aminoantipyrine and phenol substitute, p-HBS, in the 2. Test tubesrack. presence of peroxidase to yield a red quinoneimine dye. The amount of 3. Timer. colored complex formed is proportional to glucose concentration and can 4. 37° C heating block or water bath. be photometrically measured. 5. Spectrophotometer capable of accurately measuring absorbances at 500nm. REAGENT COMPOSITION When reconstituted as directed, the reagent for Glucose contains the GENERAL INSTRUCTIONS following: The reagent for Glucose is intended for use either as an automated procedure on chemistry instruments or as a manual procedure on a 1. Glucose reagent :(Concentrations refer to the reconstituted reagent) suitable spectrophotometer. Glucose Oxidase 15µlml, Peroxidase (horseradish) 1.2µlml. Mutarotase 4.0 µlml. 4-Aminoantipyrine 0.38 mM.p- PROCEDURE (AUTOMATED) Hydroxybenzene sulfonate 10 mM, and non-reactive ingredients. Consult the appropriate instrument application guide available from us. 2. Glucose standard: (100mgdl -D-glucose). PROCEDURE (MANUAL) WARNINGS AND PRECAUTIONS: 1. Prepare reagent according to instructions. 1. For in vitro diagnostic use. 2. Label test tubes: blank, standard, control, patient, etc. CAUTION: In vitro diagnostic reagents may be hazardous. Handle 3. Pipette 1.0 ml of working reagent to all tubes and place in 37°C in accordance with good laboratory procedures which dictate heating bath for at least five (5) minutes. avoiding ingestion, and eye or skin contact. 4. Add 0.01ml (10µl) of sample to respective tubes, mix and incubate at 2. Specimens should be considered infectious and handled 37°C for exactly ten (10) minutes. appropriately. 5. After incubation, zero spectrophotometer with the reagent blank. y = 1.02X + 3.1 with a coefficient of correlation of 0.99. Read and record the absorbances of all tubes at 500nm (Wavelength 3. Precision: range:500-520). Final color is stable for at least thirty (30) minutes. Within Run Mean (mgdl) S.D. C.V. * USE MULTI PURPOSE CALIBRATOR TO REPLACE 87 4.2 4.8% STANDARD. 282 5.4 1.9% Run to Run NOTE: Mean (mgdI) S.D. C.V. If the spectrophotometer being used requires a final volume greater 85 3.7 4.3% than 1.5ml for accurate reading, use 0.02ml (20µl) of sample to 287 9.6 3.3% 3.0ml of reagent. Perform the test as described above. REFERENCES PROCEDURAL LIMITATIONS 1. Holvey, D.N. ed.: The Merck Manual of Diagnostic and Therapy, The reagent is linear to 500mgdl. Samples that have glucose values Merck and Co., Inc. Rahyway, N.J. (1972). greater than 500 mgdl should be diluted with water 1:1, reassayed and 2. Cooper, G.R., CRC Crit Rev. Clin Lab. Sci. 4:101 (1973). the results multiplied by 2. 3. Keston, A.S. Colorimetric, "Enzymatic Reagents for glucose." Abstracts of Papers, 129th Meeting ACS, 131C (1956). CALCULATIONS 4. Trinder, P., "Determination of Blood Glucose Using 4- (A = Absorbance) Aminophenazone.".J. Clin. Path., 22:246 (1959). 5. Tietz, N.W., Fundamentals of Clin. Chem., Philadelphia, W.B. A (patient) x Concentration of standard = Concentration of Saunders (1970). A (standard) (mgdl) unknown (mgdl) Revised:07/96. Example: A (patient) = 0.37, A (standard) = 0.28 Concentration of standard = 100mg/dl 0.42 ------  100 = 132 mgdl 0.28 SI UNITS: To obtain results in SI units (mmolL), multiply your result in mgdl by ten (10) to convert dl to liter and divide the value by 180, the molecular weight of glucose. 10 mgdl  ---- = mgdl  0.0556 180 Example: 132mgdl x 0.0556 = 7.34mmolL QUALITY CONTROL It is recommended that controls be included in each set of assays. Commercially available control material with established glucose values may be used for quality control. The assigned value of the control material must be confirmed by the chosen application. failure to obtain the proper range of values in the assay of control material may indicate either reagent deterioration, instrument malfunction, or procedural errors. EXPECTED VALUES 70-105 mgdl6 It is strongly recommended that each laboratory establish its own normal range. PERFORMANCE CHARACTERISTICS 1. Linearity: 500mgdl. 2. Comparison: A comparison between this procedure and one utilizing phenol free produced a regression equation of  TECO DIAGNOSTICS CHOLESTEROL REAGENT SET 1268 N. Lakeview Ave. (PHENOL FREE) Anaheim, CA 92807 1-800-222-9880 INTENDED USE 2. Specimens should be considered infectious and handled For the quantitative determination of total cholesterol in human serum. appropriately. 3. Use distilled or deionized water where indicated. INTRODUCTION Cholesterol is a fatty substance found in blood, bile, and brain tissue. STORAGE AND STABILITY It serves as a precursor to bile acids, steroids, and vitamin D. The Store the reagent set at refrigerator temperature (2 - 8°C). Store the determination of serum cholesterol is a major aid in the diagnosis and reconstituted reagent at refrigerator temperature (2 - 8C). The classification of lipemias.1 Other conditions such as hepatic thyroid reconstituted reagent is stable for sixty days (60) when stored in an diseases influence cholesterol levels.2 amber bottle at 2 - 8°C.4 Enzymatic methods have replaced older methodologies involving REAGENT DETERIORATION cholesterol esterase, oxidase, and trinders color system. Allain et al. The reagent should be discarded if: developed a total enzymatic technique in which hydrogen peroxide 1. Turbidity has occurred; turbidity may be a sign of during the oxidation of cholesterol is used in conjunction with contamination. peroxidase, 4-aminoantipyrine, and phenol to form a quinoneimine 2. Moisture has penetrated the vial and caking has occurred. dye.3 This reagent employs p-hydroxy benzene sulfonic acid (p-HBS), 3. The reagent fails to meet linearity claims or fails to recover in place of phenol to produce a quinoneimine dye with greater control values in the stated range. absorbance at 520nm and a surfactant to facilitate the completion of reaction. SPECIMEN COLLECTION 1. Test specimens should be serum and free from hemolysis. PRINCIPLE 2. Cholesterol in serum is reported stable for seven days (7) at room The enzymatic reaction sequence employed in the assay of cholesterol temperature (18 - 30°C) and six months (6) when frozen and is as follows: properly protected against evaporation. Cholesterol Esters C. Esterase Cholesterol + Fatty Acids INTERFERING SUBSTANCES Anticoagulants such as fluoride and oxalate will result in false low Cholesterol + 02 C. Oxidase  Cholesten-3-one + H202 values.5 The test is not influenced by hemoglobin values up to 200 mg/dl or by bilirubin levels up to 10 mg/dl. Interference from grossly 2 H202 + 4-Aminoantipyrine icteric and heavily hemolyzed specimens is correctible by use of a serum/plasma blank. + p-HBS H.Peroxidase Quinoneimine + 2 H20 (red dye) MATERIALS REQUIRED BUT NOT PROVIDED 1. Spectrophotometer capable of measuring absorbances at 520 nm. Cholesterol esters are hydrolyzed to produce cholesterol. Hydrogen 2. Test tubes and rack. peroxide is then produced from the oxidation of cholesterol-by- 3. Accurate pipetting/measuring devices. cholesterol oxidase. In a coupled reaction catalyzed by peroxidase, 4. Timer. quinoneimine dye colored red is formed from 4-aminoantipyrine, p- 5. Heating block (37C). HBS, and hydrogen peroxide. The absorption at 520 nm of the solution of this dye is proportional to the concentration of cholesterol GENERAL INSTRUCTIONS in the sample. The reagent for Cholesterol is intended for use either as an automated procedure on chemistry instruments or as a manual procedure on a REAGENT COMPOSITION suitable spectrophotometer. When reconstituted as directed, the reagent for Cholesterol contains the following: PROCEDURE (AUTOMATED) Consult the appropriate instrument application guide available from 1. Cholesterol Reagent: Teco. (Concentrations refer to the reconstituted reagent.) 4- Aminoantipyrine 0.6mM, Sodium Cholate 8.0mM, Cholesterol PROCEDURE (MANUAL) Esterase > 150 U/L, Cholesterol Oxidase > 200U/L, Horseradish 1. Prepare reagent according to instructions on vial label. Peroxidase > 1500U/L, p-Hydroxy benzene sulfonate 20mM, 2. Label test tubes: blank, standard, control, patient, etc. Buffer 125mM, pH 6.8, non-reactive stabilizers, and fillers. 3. Pipette 1.0 ml of reagent to all tubes and pre-warm at 37°C for at 2. Cholesterol Standard: least two (2) minutes. 200mg/dl cholesterol in alcohol. 4. Add 0.01 ml (10 µl) of sample to respective tubes, mix, and return Store at 2 - 8° C and keep tightly capped. to 37°C 5. Incubate all tubes at 37°C for ten (10) minutes. 6. Zero spectrophotometer with the reagent blank at 520 nm. WARNINGS AND PRECAUTIONS (Wavelength range: 500-550 nm). 1. For in vitro diagnostic use. Caution: Pipetting by mouth is not 7. Read and record absorbances of all tubes. recommended for any laboratory reagent.  * TC - MULTI PURPOSE CALIBRATOR MAY BE USED 4. Specificity: Cholesterol Oxidase is not totally specific for TO REPLACE STANDARD. cholesterol. Other analogs of cholesterol (dihydrocholesterol, 7- dehydrocholesterol, 20 hydroxycholesterol, etc.) are also oxidized. N0TE: If the spectrophotometer being used requires a final volume These analogs do not normally occur in any appreciable amounts greater than l.0 ml for accurate reading, use 0.025 m1 (25 µ1) of in serum. sample to 3.0 ml of reagent. Perform the test as described above. REFERENCES PROCEDURAL LIMITATIONS 1. Beaumont, J.L., Crison, L.A., Cooper, G.R., Feifar, Z., The reagent is linear to 500 mg/dl. Frederickson, D.S., and Strasser, T.; "Classification of 1. Samples with values above 500 mg/dl should be diluted 1:1 with Hyperlipidemias and Hyperlipoproteinemias." Standard isotonic saline and re-run. Multiply final results by two (2). Methods of Clinical Chemistry vol. 9, Academic Press, 2. Grossly lipemic serums require a "sample blank." Add 0.02 ml New York, NY (1972). (20 µl) of sample to 2.5 ml saline, mix, and read the absorbance 2. Holvey, D.N., ed. The Merck Manual of Diagnosis and against water. Subtract this value from the patient absorbance to Therapy. Merck and Co., Inc. Rahyway, NJ (1972). obtain the corrected reading. 3. Aliain, C.C., et. al., Clin. Chem. 20:470 (1974). 4. Perlstern, M.T., et al., Micro. Chem. J. 22:403 (1977). CALCULATIONS 5. Young, D.S., et al., Clin. Chem. 21 No. 5 (1975). (A= Absorbance) 6. Naito, H.K., et. al., Clin. Chem. 34:193 (1988). A (patient) x Concentration of standard. Concentration of C509: 12/2017 = A (standard) (mg/dl) patient (mg/dl) Manufactured by: Example: TECO DIAGNOSTICS 1268 N. LAKEVIEW AVE. A (patient) = 0.40, A (standard) = 0.32, ANAHEIM, CA 92807 Concentration of standard = 200 mg/dl. U.S.A. 0.40 x 200 = 250 mg/dl 0.32 QUALITY CONTROL It is recommended that controls be included in each set of assays. Commercially available control material with established cholesterol values may be used for quality control. The assigned value of the control material must be confirmed by the chosen application. Failure to obtain the proper range of values in the assay of control material may indicate reagent deterioration, instrument malfunction, or procedural errors. EXPECTED VALUES6 It is strongly recommended that each laboratory establish its own normal range. RISK CLASSIFICATION TOTAL CHOLESTEROL IN BLOOD (mg/dl) Desirable  200 Borderline 200-239 High  240 PERFORMANCE CHARACTERISTICS 1. Linearity: 500 mg/dl. 2. Comparison: A comparison between this procedure and one utilizing phenol free produced a regression equation of Y = 0.95X + 10.3 with a coefficient of correlation of 0.98. 3. Precision: Within Run Mean (mg/dl) S.D. C.V.(%) 127 3.6 2.8 330 4.9 1.4 Run to Run Mean (mg/dl) S.D. C.V.(%) 130 4.7 3.6 324 8.2 2.5  TECO DIAGNOSTICS TRIGLYCERIDE - GPO 1268 N. Lakeview Ave. Anaheim, CA 92807 LIQUID REAGENT 1-800-222-9880 INTENDED USE 4. Reagent and standard contain sodium azide as a preservative. This For the In Vitro quantitative determination of Triglycerides in serum or may react with copper or lead plumbing to form explosive metal plasma. azides. Upon disposal, flush with large amount of water to prevent azide build up. INTRODUCTION Triglycerides are esters of fatty acids and are hydrolyzed to glycerol REAGENT PREPARATION and free fatty acids. Triglyceride determinations when performed in Triglyceride reagent and standard are provided in a ready-to-use form. conjunction with other lipid assays are useful in the diagnosis of No preparation is necessary. primary and secondary hyperlipoproteinemia. They are also of interest in following the course of diabetes mellitus, nephrosis, biliary STORAGE AND STABILITY obstruction and various metabolic abnormalities due to endocrine Both the Triglyceride reagent and standard must be stored at 2 - 8°C. disturbances. The reagent may be used until the expiration date indicated on the package label when stored as directed. Protect from direct light. Avoid Standard methods for the measurement of triglyceride concentrations microbial contamination. have involved either enzymatic or alkaline hydrolysis to liberate glycerol. This formulation makes use of the enzymatic hydrolysis and REAGENT DETERIORATION quantification since it is specific and not subject to interference by The reagent should be discarded if: phospholipids.1 1. The initial absorbance of the reagent against water is greater than 0.500 when measured at 520 nm. PRINCIPLE 2. The reagent fails to meet linearity claims or fails to recover stated The enzymatic reaction sequence employed in the assay of values. Note: A yellow or pink coloration is normal. Triglycerides is as follows: 3. The reagent is turbid or displays evidence of bacterial Triglycerides Lipase  Glycerol + Fatty Acids contamination. Glycerol + ATP Glycerol Kinase  Glycerol-l-phosphate + ADP SPECIMEN COLLECTION 1. Fresh, clear, non-hemolyzed serum from fasting patients is Glycerol- 1-Phosphate + 02 GPO  DAP + H202 recommended. 2. Triglycerides in serum appear stable for three (3) days when stored H202 + 4-AA + DHBS Peroxidase  Quinoneimine Dye + 2H20 at 2 - 8°C.4 3. Prolonged storage of the samples at room temperature is not The present procedure involves hydrolysis of triglycerides by lipase. recommended since other glycerol containing compounds may The glycerol concentration is then determined by enzymatic assay hydrolyze, releasing free glycerol. coupled with Trinder reaction that terminates in the formation of a 4. Blood collection devices lubricated with glycerin (glycerol) quinoneimine dye. The amount of the dye formed, determined by its should not be used. absorption at 520 nm, is directly proportional to the concentration of triglycerides in the samples.2, 3 INTERFERENCES Glycerol in rubber stoppers or in contaminated glassware will elevate REAGENT COMPOSITION triglyceride levels. Lipemic or grossly icteric samples will cause falsely 1. Triglyceride Liquid reagent contains the following: elevated results consequently a patient blank should be run. Samples ATP 0.5 mmol/L, Magnesium acetate 12 mmol/L, 4-Chlorophenol with gross hemolysis or high bilirubin values will produce falsely 3.5 mmol/L, 4-Aminophenazone 0.3 mmol/L, Glycerol Phosphate elevated triglyceride values. A number of drugs and substances affect Oxidase > 4500 UL, Lipase >200,000 UL, Glycerol kinase >250 the measurement of triglyceride.5 UL, Peroxidase >2,000 UL, Buffer (pH 7.4) 50 mmol/L, surfactants, stabilizers, and preservatives. MATERIALS PROVIDED 2. Triglyceride standard contains glycerol with surfactant to yield 200 1. Triglyceride GPO Liquid Reagent mgdl triglycerides as triolein. Sodium azide 0.1% is added as a 2. Triglyceride Standard (200 mgdl) preservative. MATERIALS REQUIRED BUT NOT PROVIDED 1. Spectrophotometer capable of measuring absorbances at 500-550 WARNINGS AND PRECAUTIONS nm 1. For In Vitro diagnostic use. 2. Test tubes and rack 2. Avoid ingestion of reagent as toxicity has not yet been determined. 3. Accurate pipetting devices 3. All specimens and controls should be considered infectious and 4. Constant temperature incubator set at 37° C handled appropriately. 5. Timer GENERAL INSTRUCTIONS 0.946x + 5.373. (Comparison studies were performed according to The reagent for triglycerides is intended for use either as an automated NCCLS Tentative Guideline, EP9-T.) procedure on chemistry instruments or as a manual procedure on a Precision: suitable spectrophotometer. Within-Run Serum 1 Serum 2 AUTOMATED PROCEDURE Mean (mg/dl) 43.0 127.0 Refer to appropriate application manual available. Std. Deviation (mg/dl) 1.19 3.83 C.V. (%) 2.78 3.02 MANUAL PROCEDURE 1. Label tubes: “blank”, “standard”, “control”, “patient”, etc. Run-to-Run 2. Pipette l.0 ml of reagent into all tubes. Serum 1 Serum 2 3. Place all tubes in a 37° C heating block for at least 4 minutes. Mean (mg/dl) 42.3 124.1 4. Add 0.010 ml (10 l) of sample to respective tubes and mix. Std. Deviation (mg/dl) 1.99 4.12 5. Incubate all tubes for five (5) minutes at 37° C. C.V. (%) 4.71 3.32 6. Zero spectrophotometer at 520 nm with reagent blank (Wavelength range: 500-550). REFERENCES 7. Read and record absorbances of all tubes. 1. Searcy, R.L.: Diagnostic Biochemistry, McGraw-Hill, New Note: Final color is stable for sixty (60) minutes at room temperature. York (1969). 2. Fossati, P., Principle, L.: Clin. Chem. 28:2077 (1982). TC - MULTI PURPOSE CALIBRATOR MAY BE USED TO 3. McGowan, M.W, et al.: Clin. Chem. 29:538 (1983). REPLACE STANDARD. 4. Wybenga, D.R. And Inkpen, J.A.: Clinical Chemistry: Principles and Techniques. Harper and Row, Hagerstown, MD PROCEDURAL LIMITATIONS 1460 (1974). The reagent is linear to 1000 mgdl (11.4 mmol/L), specimens above 5. Young, D.S. Pestaner, L.C. and Gibberman, V.: Clin. Chem. this limit must be diluted 1:1 with water, reassayed and multiplied the 21:11 (1975). results by two to compensate for the dilution. 6. Sisson, J.A.: Handbook of Clinical Pathology, J.B. Lippincott Co., (1976). QUALITY CONTROL 7. Tiffany, T. O., et. al. Clin. Chem., 20:476 (1974). It is recommended that controls be included in each set of assays. Commercially available control material with established triglyceride T532: 07/2018 values may be used for quality control. The assigned value of the control material must be confirmed by the chosen application. Failure to obtain the proper range of values in the assay of control material may Manufactured by: indicate either reagent deterioration, instrument malfunction, or TECO DIAGNOSTICS procedural errors. 1268 N. LAKEVIEW AVE. ANAHEIM, CA 92807 U.S.A. CALCULATIONS Triglycerides results are expressed as mg/dl A = Absorbance A (patient)  Concentration = Concentration of patient A (standard) of standard (mgdl) (mgdl) Example: 0.24  200 = 154.8 mgdl 0.31 NOTE: To obtain the results in SI units (mmolL) multiply the result in mgdl by 0.0113. EXPECTED VALUES 36 – 165 mgdl6 It is strongly recommended that each laboratory establish its own normal range. PERFORMANCE CHARACTERISTICS Linearity: 1000 mgdl Sensitivity: Based on an instrument resolution of A = 0.001, this procedure has a sensitivity of 1.3 mgdl. Comparison: A group of 91 sera ranging in Triglyceride values from 12 to 1030 mg/dl were assayed by this method and by a similar commercially available reagent. Comparison of the results yielded a correlation coefficient of 0.997 and the regression equation was y =  DIRECT LDL TECO DIAGNOSTICS CHOLESTEROL REAGENT 1268 N. Lakeview Ave. (MANUAL AND AUTOMATED) Anaheim, CA 92807 1-800-222-9880 INTENDED USE For the direct quantitative determination of low density lipoprotein cholesterol SPECIMEN COLLECTION AND STORAGE (LDL-C) in human serum or plasma on automated analyzer For in vitro Serum, EDTA-treated or heparinized plasma are the recommended specimens. diagnostic use only. Patients are not required to fast prior to blood collection. Serum: Collect whole blood by venipuncture and allow to clot. Centrifuge SUMMARY AND EXPLANATION OF THE TEST and remove the serum as soon as possible after collection (within 3 Plasma lipoproteins are spherical particles that contain varying amounts of hours).10 cholesterol, triglycerides, phospholipids, and proteins. The phospholipid, free Plasma: Specimens may be collected in EDTA or heparin. Centrifuge and cholesterol and protein constitute the outer surface of the lipoprotein particle, the remove the plasma as soon as possible after collection (within 3 inner core contains mostly esterified cholesterol and triglycerides. These hours).10 particles serve to solubilize and transport cholesterol and triglycerides in the If not analyzed promptly, specimens may be stored at 2-8°C for up to 5 days. If bloodstream. specimens must be stored for more than 5 days, they may be frozen at –80°C. The relative proportions of protein and lipid determine the density of these plasma lipoproteins and provide a basis for their classification.1 The classes are: INTERFERENCES very low density lipoproteins (VLDL), low density lipoproteins (LDL), and high All interference studies were conducted according to the procedures density lipoprotein (HDL). Numerous clinical studies have shown that the recommended in NCCLS guideline No. EP7-P for interference testing in clinical different lipoprotein classes have varied effects. 2-4 The studies all point to LDL chemistry.12 Hemoglobin at levels up to 400 mg/dl, Bilirubin at levels up to 20 cholesterol as the key factor in the pathogenesis of artherosclerosis and coronary mg/dl and Triglycerides to 1500 mg/dl were found to exhibit negligible artery disease (CAD),2-8 while HDL cholesterol has often been observed to have interference (