Homocysteine
| Label Mnemonic: | HOMCY |
| Epic code: | LAB93 |
| Downtime form: | A-1a Doctor/Provider Orders - Pathology Core and Specialty Care Nursery |
Chemistry
6240 RCP
356-3527
6240 RCP
356-3527
Specimen(s):
Plasma
Collection Medium:
 |
| Plasma Separator Tube 4.5 mL |
Alternate
Collection Media:
Call laboratory for additional acceptable specimen collection containers.
Minimum:
Adults - 3 mL whole blood in a light green top tube
Pediatrics - ONE Microtainer®
Pediatrics - ONE Microtainer®
Delivery Instructions:
Mix well and place on wet ice. Keep on ice and deliver to
laboratory immediately.Testing Schedule:
24 hrs/day, 7 days a week, including holidays.
Turn Around
Time:
1 hour (upon receipt in laboratory)
Reference Range:
< 10 μmol/L Patients with end stage renal disease may have elevated levels of cystathionine which may cause a significant positive interference in the homocysteine assay.
Test
Limitations:
Homocysteine plasma levels are dependent on B-Vitamin status. The AHA
target for those with cardiovascular or other risks is < 10
micromol/L.
(Circulation 1999;99:178-182.)
Cystathionine is measured with homocysteine, but in the general population the cystathionine level (0.065 to 0.03 umol/l) has a negligible effect. In very rare, end stage renal disease patients with severe metabolic disturbances, cystathionine levels may rise dramatically and cause greater than 20% interference. Refer to the SPECIFICITY section of the package insert for cross-reactivity data of this drug. Drugs, such as methotrexate, carbamazepine, phenytoin, nitrous oxide, or 6-azauridine triacetate may affect plasma concentration of homocysteine. The mechanism of action affects different parts of the metabolic pathway of homocysteine. Serum concentrations can be up to 10% higher than EDTA plasma concentrations.
Hemolysis: No significant interference up to an H index of 500 (approximate hemoglobin concentration: 500 mg/dL).
Lipemia: No significant interference up to an L index of 500 (approximate triglycerides concentration: 1000 mg/dL). Note there is poor correlation between turbidity and triglyceride concentration.
Icterus: No significant interference up to an I index of 20 (approximate conjugated and unconjugated bilirubin concentration: 20 mg/dL).
Cystathionine is measured with homocysteine, but in the general population the cystathionine level (0.065 to 0.03 umol/l) has a negligible effect. In very rare, end stage renal disease patients with severe metabolic disturbances, cystathionine levels may rise dramatically and cause greater than 20% interference. Refer to the SPECIFICITY section of the package insert for cross-reactivity data of this drug. Drugs, such as methotrexate, carbamazepine, phenytoin, nitrous oxide, or 6-azauridine triacetate may affect plasma concentration of homocysteine. The mechanism of action affects different parts of the metabolic pathway of homocysteine. Serum concentrations can be up to 10% higher than EDTA plasma concentrations.
Hemolysis: No significant interference up to an H index of 500 (approximate hemoglobin concentration: 500 mg/dL).
Lipemia: No significant interference up to an L index of 500 (approximate triglycerides concentration: 1000 mg/dL). Note there is poor correlation between turbidity and triglyceride concentration.
Icterus: No significant interference up to an I index of 20 (approximate conjugated and unconjugated bilirubin concentration: 20 mg/dL).
CPT Code:
83090
See Additional Information:
Specimens Requiring Immediate Delivery
Specimens Requiring Immediate Delivery