Specimen

Plasma

Collection Medium:

Alternate
Collection Media:

Call laboratory for additional acceptable specimen collection 
containers.

Minimum:

Adults - 2 mls whole blood in a light green top tube.
Pediatrics - (2) 0.6 ml heparin microtainers (Lithium or Sodium)

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.

Analytic Time:

1 hour (upon receipt in laboratory)

Reference Range:

< 10 umol/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.

CPT Code:

83090

See Additional Information:
Specimens Requiring Immediate Delivery