Test Details
Methodology
Based on the catalytic action of hemoglobin on the oxidation of TMB by hydrogen peroxide; rate measured by spectrophotometry
Result Turnaround Time
3 - 4 days
Turnaround time is defined as the usual number of days from the date of pickup of a specimen for testing to when the result is released to the ordering provider. In some cases, additional time should be allowed for additional confirmatory or additional reflex tests. Testing schedules may vary.
Use
Evaluate hemolytic anemia, especially intravascular hemolysis. Plasma hemoglobin is increased with intravascular hemolysis, ABO incompatible transfusion, traumatic hemolysis, falciparum malaria, burns, and march hemoglobinuria. Increase may occur in some cases of extravascular hemolysis, delayed transfusion reaction, slight increase in sickle cell anemia, and β-thalassemia.
Limitations
High (>20 mg/dL) bilirubin, turbidity, methemalbuminemia, lipemic plasma, and hemolysis during or after venipuncture may cause falsely elevated values in the plasma hemoglobin test (method based on peroxide oxidation of TMB).
Results of this test are labeled for research purposes only by the assay's manufacturer. The performance characteristics of this assay have not been established by the manufacturer. The result should not be used for treatment or for diagnostic purposes without confirmation of the diagnosis by another medically established diagnostic product or procedure. The performance characteristics were determined by LabCorp.
Specimen Requirements
Specimen
Plasma
Volume
1 mL
Minimum Volume
0.1 mL (Note: This volume does not allow for repeat testing.)
Container
Green-top (heparin) tube
Collection Instructions
Recommended procedure for collecting sample without inducing hemolysis: An 18-gauge needle with attached infusion tubing is used. Place the tourniquet lightly around the upper arm. Puncture an antecubital vein with as little trauma as possible. Release the tourniquet and clamp the tubing off as soon as blood return is seen. First collect 3 mL blood in a red-top tube with the rubber top off. Then, collect 5 mL in an anticoagulated tube with the top off. Clamp the tubing, withdraw the needle, and apply a pressure bandage to the site until residual bleeding is stopped. Recap the anticoagulant tube and gently mix three to five times. This specimen is used for the plasma hemoglobin determination. Centrifuge and separate plasma from red cells immediately following collection and transfer plasma to a transfer tube.
Stability Requirements
| Temperature | Period |
|---|---|
| Room temperature | 6 days |
| Refrigerated | 6 days |
| Frozen | 6 days |
| Freeze/thaw cycles | Stable x3 |
Reference Range
<5 mg/dL (if conditions are optimal). Values obtained between 5−15 mg/dL should be interpreted with caution since such variables as suboptimal venipuncture may increase results to this range.
Storage Instructions
Refrigerate at 2°C to 8°C or freeze at -20°C for up to six days.
Patient Preparation
Patient should not exercise just prior to the test.
Causes for Rejection
Traumatic venipuncture causing hemolysis; very icteric or lipemic specimen; specimen not heparinized plasma
LOINC® Map
| Order Code | Order Code Name | Order Loinc | Result Code | Result Code Name | UofM | Result LOINC |
|---|---|---|---|---|---|---|
| 005595 | Hemoglobin, Free, Plasma | 721-1 | 005596 | Hemoglobin, Free, Plasma | mg/dL | 721-1 |
| Order Code | 005595 | |||||
| Order Code Name | Hemoglobin, Free, Plasma | |||||
| Order Loinc | 721-1 | |||||
| Result Code | 005596 | |||||
| Result Code Name | Hemoglobin, Free, Plasma | |||||
| UofM | mg/dL | |||||
| Result LOINC | 721-1 |