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PRINCIPLE OF THE METHOD
STABILITY AND STORAGE
All reagents should be stored at 2-8 . Unopened Homocysteine Biochemical Assay is an enzymatic reagents are stable until the expiration date on the label. TOTAL HOMOCYSTEINE BIOCHEMICAL ASSAY KIT
method which measures total homocysteine in plasma. Once opened, store tightly capped at 2-8 and use Bound HCY is reduced to free HCY which then within 30 days. Reconstituted reagent 1 should be
INTENTED USE
Epidemiological studies have investigated the catalyzed by recombinant methionine α,γ-lyase (HCY used within 48 hours.
relationship between HCY levels in blood and CVD. A enzyme) to produce H2S. The H2S subsequently reacts Homocysteine Biochemical Assay Kit is an in vitro meta analysis of 27 epidemiological studies, including with a chromophore, and the product is measured SPECIMEN COLLECTION AND PREPARATION
assay for the quantitative determination of total more than 4000 patients, estimated that a 5 µM optically at 660nm. The optical density is proportional to z Fresh EDTA-plasma free from homolysis or turbidity increase in HCY was associated with an odds ratio for is recommended for homocysteine determination. coronary artery disease (CAD) of 1.6 for men and 1.8 z Overnight fasting is recommended before blood is INTRODUCTION
for women. Peripheral arterial disease also showed a KIT COMPOSITION
Over 1 million of Americans died of cardiovascular 1. Reagent 1 Buffer: Tris buffer 9mL×10 z Place all specimens on ice after collection and prior disease (CVD) such as heart attack or stoke. It was to processing, and separate plasma from the blood long thought that CVD is related to the increased level Certain patient groups with anemia and/or asthenia also 3. HCY Enzyme: Methionine α,γ-lyase 10vials cells by centrifugation for up to 6 hours. of cholesterol in the blood , but yet 25% patients with demonstrate increased levels of plasma or serum HCY. z The plasma samples may be stored at 2-8 heart attack have no obviously elevated blood Patients with chronic renal disease experience an cholesterol level or other risk factors been observed. excess morbidity and mortality due to arteriosclerotic WARNINGS AND PRECAUTIONS
z The plasma samples should be stored at -20 However, the metabolism of homocysteine (HCY) is CVD. Elevated concentration of HCY is a frequently z For in vitro diagnostic use only. found to be related to the CVD or stoke in recent observed finding in the blood of these patients. z Not to be used internally in humans and animals. Although such patients may lack some of the vitamins z The assay should be performed by the doctor or the PROCEDURE
involved in the metabolism of HCY, the increased levels Homocysteine is a thiol-containing amino acid produced of HCY are mainly due to impaired removal of HCY z Normal precautions for handling laboratory reagents Materials supplied
by the intracellular demethylation of methionine. HCY is Refer to the section entitled “KIT COMPOSITION”. exported into plasma where it circulates mostly in its z Avoid contact with skin and eyes. If the reagents oxidized forms bound to plasma proteins. Smaller Severely elevated concentrations of HCY are found in come in contact with skin or eyes, rinse immediately Materials required but not supplied
amounts of reduced homocysteine and disulfide subjects with “homocystinuria”, a rare genetic disorder with water. Consult a physician if necessary. homocystin (HCY-SS-HCY) are present. Total of the enzymes involved in the metabolism of HCY. z Do not use reagents past the expiration date stated homocysteine (tHCY) represents the sum of all HCY Patients with homocystinuria exhibit mental retardation, species found in plasma and serum. HCY is either early arteriosclerosis and arterial and venous z Do not mix or use reagents from one test kit with Reagent preparation
metabolised to cysteine or to methionine. In the vitamin thromboembolism(8). Drugs such as methotrexate, Reagent 1 should be prepared freshly before use. B6 dependent transsulphuration pathway HCY is carbamazepine, phenytoin, nitrous oxide and z Reagents contain sodium azide as a preservative. z Open a foil bag which contains one vial of HCY irreversibly catabolized to cysteine. A major part of HCY penicillamine interfere with the HCY metabolism and Sodium azide may form explosive compounds in Enzyme and one vial of Reducing reagent. Draw out is remethylated to methionine, mainly by the folate and metal drain lines. Flush drains with large amount of the vial of Reducing reagent and add about 2mL cobalamin-dependent enzyme methionine synthase. Reagent 1 Buffer into it. Replace the stopper HCY accumulates and is excreted into the blood when z Additional safety information concerning storage and immediately and gently mix by inversion several these reactions are impaired(4-5). The elevated handling of this kit is provided within the Material times. Let it stand for 1 minute. Transfer the concentration of homocysteine in the blood is reconstituted solution back to the original Reagent 1 considered an independent risk factor of CVD. buffer bottle. Recap and gently mix the reconstituted solution by inversion several times. Take 2mL recommended for monitoring the kit performance. The 3. Nygard O, Nordrehaug JE, Refsum H, et al. Plasma reconstituted solution back to the vial of Reducing range of acceptable control limits should be established homocysteine levels and mortality in patients with reagent. Replace the stopper immediately and rinse by individual laboratories. The currently acceptable coronary artery disease. N Engl J Med 1997; 337: the vial by inversion several times. Transfer the rinsed solution back to the reconstituted solution. 4. Ueland PM. Homocysteine species as components Draw out the vial of HCY Enzyme and add about LIMITATIONS OF THE PROCEDURES
of plasma redox thiol status. Clin Chem 1995; 2mL reconstituted solution into it. Replace the z Follow the suggested procedure will result in the stopper immediately and gently mix by inversion confident determination, especially the plasma 5. Finkelstein JD, Methionine metabolism in mammals. several times. Let it stand for 1 minute. Transfer the sample preparation and the Reagent 1 preparation. reconstituted solution back to the original Reagent 1 z Hemolytic, icteric or lipemic samples may interfere 6. Boushey CJ, Beresford SAA, Omenn GS, et al. buffer bottle. Recap and gently mix the reconstituted LOWER LIMIT of DETECTION
Quantitative assessment of plasma homocysteine solution by inversion several times. Take 2mL The lower limit of detection of this methods is estimated as a risk factor for vascular disease. JAMA 1995; prepared R1 back to the vial of HCY Enzyme. PERFORMANCE CHARACTERISTICS
Replace the stopper immediately and rinse the vial The following performance data was obtained using a 7. Bostom AG, Lathrop L. Hyperhomocysteinemia in by inversion several times. Transfer the rinsed FUNCTIONAL SENSITIVITY
end-stage renal disease: prevalence, etiology, and solution back to the prepared R1. Let it stand for 10 The functional sensitivity of this methods is estimated to potential relationship to arteriosclerotic outcomes. minutes. Mix the prepared R1 well prior to use. Avoid DILUTION LINEARITY
foaming during the preparation. The fresh prepared 8. Malinow MR. Plasma homocysteine and arterial CORRELATION of METHODS
occlusive disease: a mini-review. Clin Chem 1995; z The prepared R1 is stable within 48 hours. Once
past 48 hours, discard the remaining R1.
9. Ueland PM, Refsum H, Stabler SP, et al. Total homocysteine in plasma or serum: methods and Assay procedure
clinical applications. Clin Chem 1993; 39: 1764- An example of standard protocol automated application: Formosa Biomedical Technology Corp.
PRECISION
5F, Front Building, No.201, Tunghwa N. Road, Taipei, Parameter for Hitachi 917 is available on request. No.3, Longquan Road, Longtan, Jiaoxi, Yilan, Taiwan The tHCY levels are calculated and printed by the REFERENCE
1. McCully KS. Homocysteine and vascular disease. QUALITY CONTROL AND REFERENCE RANGE
2. Selhub J, Jacques PF, Bostom AG, et al. A quality control program is recommended for all clinical laboratories. The analysis of control material in both concentrations and extracranial carotid-artery normal and abnormal ranges with each assay is stenosis. N Engl J Med 1995; 332: 286-291.

Source: http://www.fbc.com.tw/j2fbs/fbc_en/medical/download/HCY_20060223.pdf