Home
HelpTest ID P50B Oxygen Dissociation, P50, Erythrocytes
Useful For
Identifying hemoglobin variants associated with polycythemia or cyanotic and hypoxic disorders
Profile Information
| Test ID | Reporting Name | Available Separately | Always Performed |
|---|---|---|---|
| PINT | P50 Interpretation | No | Yes |
| P50P | Oxygen Dissociation P50 | No | Yes |
| CTRL | P50 Shipping Control Vial | No | Yes |
Testing Algorithm
See Diagnostic Approach to Suspected Erythrocytosis in Special Instructions.
Special Instructions
Method Name
Hemox-Analyzer Measures and Plots O2 Saturation
Reporting Name
Oxygen Dissociation P50, RBCSpecimen Type
ControlWB Sodium Heparin
Specimens must arrive within 72 hours of draw.
A whole blood sodium heparin specimen and a control specimen are required.
Forms: If not ordering electronically, complete, print, and send a Benign Hematology Test Request Form (T755) with the specimen (http://www.mayomedicallaboratories.com/it-mmfiles/benign-hematology-test-request-form.pdf)
Patient:
Container/Tube: Green top (sodium heparin)
Specimen Volume: 5 mL
Collection Instructions:
1. Immediately refrigerate specimens after draw. Keep at refrigerated temperatures 2 to 8° C. Do not freeze. Freezing causes sample lysis, and tests will not be performed on hemolyzed specimens.
2. Send specimen in original tube. Do not aliquot.
3. Rubber band patient specimen and control vial together. Control must accompany the patient sample at all times to ensure the reliability of testing results.
4. Be sure specimen and control are stored and transported together at refrigerate temperature, carefully following proper handling and shipping instructions.
Additional Information: Patient's age and sex are required.
Normal Shipping Control:
Container/Tube: Green top (sodium heparin)
Specimen Volume: 5 mL
Collection Instructions:
1. Draw a control specimen from a normal (healthy), unrelated, nonsmoking person at the same time as the patient.
2. Label clearly on outermost label normal control.
3. Immediately refrigerate specimen after draw. Keep at refrigerated temperatures 2 to 8° C. Do not freeze.
4. Send specimen in original tube. Do not aliquot.
5. Rubber band patient specimen and control vial together. Control must accompany the patient sample at all times to ensure the reliability of testing results.
Specimen Minimum Volume
1 mL
Specimen Stability Information
| Specimen Type | Temperature | Time |
|---|---|---|
| Control | Refrigerated | 72 hours |
| WB Sodium Heparin | Refrigerated | 72 hours |
Clinical Information
Abnormal oxygen affinity is demonstrated in the presence of some hemoglobin variants:
-High oxygen affinity causes erythrocytosis
-Low oxygen affinity causes cyanosis and/or low oxygen saturation.
Increased oxygen affinity of hemoglobin, reflected in a low p50, left-shifted oxygen dissociation curve, and loss of normal sigmoidal configuration, are characteristic of many hemoglobin variants that are responsible for polycythemia. Measurement of oxygen affinity is an important method for diagnosis of these disorders.
Reference Values
≥12 months: 24-30 mm Hg
Reference values have not been established for patients who are <12 months of age.
Cautions
To ensure valid results, the specimen must be ≤72 hours old.
The shipping control specimen is required to adequately interpret these cases, as temperature extremes can impact the integrity of the specimen and give falsely altered results.
Resulting Cautions:
P50 results will be reported if the shipping control is normal. The shipping control is necessary for ensuring valid results. If the specimen is compromised, such as during transport, this often results in an abnormal result in both the control and specimen.
If the shipping control is abnormal and the p50 results are within normal range, the results will be reported; however, a comment will be added to the report indicating that the shipping control was not entirely satisfactory.
The test will be cancelled if the patient specimen and shipping control are both abnormal.
Day(s) Performed
Monday through Sunday
Report Available
1 dayPerforming Laboratory
Mayo Medical Laboratories in Rochester
Test Classification
This test was developed and its performance characteristics determined by Mayo Clinic in a manner consistent with CLIA requirements. This test has not been cleared or approved by the U.S. Food and Drug Administration.CPT Code Information
82820