Test Catalog

Test Id : PLHBB

Plasma Free Hemoglobin, Plasma

Useful For
Suggests clinical disorders or settings where the test may be helpful

Determining whether hemolysis is occurring such as from:

-Transfusion reaction

-Mechanical fragmentation of red blood cells

-Relative comparison to baseline levels in extracorporeal membrane oxygenation and centrifugal ventricular assist device patients to assess pump disruption

Method Name
A short description of the method used to perform the test

Spectrophotometry (SP)

NY State Available
Indicates the status of NY State approval and if the test is orderable for NY State clients.


Reporting Name
Lists a shorter or abbreviated version of the Published Name for a test

Plasma Free Hemoglobin, P

Lists additional common names for a test, as an aid in searching

Plasma Free Hemoglobin

Plasma Hemoglobin

Specimen Type
Describes the specimen type validated for testing

Plasma EDTA

Specimen Required
Defines the optimal specimen required to perform the test and the preferred volume to complete testing

Collection Container/Tube: Lavender top (EDTA)

Submission Container/Tube: Plastic vial

Specimen Volume: 2 mL

Collection Instructions:

1. Centrifuge and transfer plasma to a plastic vial within 2 hours of collection.

2. Results could be falsely elevated due to artifactual red blood cell lysis if not centrifuged within 2 hours of collection.


If not ordering electronically, complete, print, and send a Benign Hematology Test Request Form (T755) with the specimen.

Specimen Minimum Volume
Defines the amount of sample necessary to provide a clinically relevant result as determined by the Testing Laboratory

1.5 mL

Reject Due To
Identifies specimen types and conditions that may cause the specimen to be rejected

Gross hemolysis OK
Gross lipemia OK

Specimen Stability Information
Provides a description of the temperatures required to transport a specimen to the performing laboratory, alternate acceptable temperatures are also included

Specimen Type Temperature Time Special Container
Plasma EDTA Refrigerated (preferred) 20 days
Frozen 30 days
Ambient 4 days

Useful For
Suggests clinical disorders or settings where the test may be helpful

Determining whether hemolysis is occurring such as from:

-Transfusion reaction

-Mechanical fragmentation of red blood cells

-Relative comparison to baseline levels in extracorporeal membrane oxygenation and centrifugal ventricular assist device patients to assess pump disruption

Clinical Information
Discusses physiology, pathophysiology, and general clinical aspects, as they relate to a laboratory test

Hemoglobin is contained within erythrocytes and significant amounts of "free hemoglobin" (outside the red blood cell [RBC]) are not normally present in plasma. This free hemoglobin is also called plasma hemoglobin.


Normal blood draw procedures cause a limited degree of unavoidable disruption and therefore a small amount of free hemoglobin may normally be present. When detectable, the total plasma hemoglobin and a subcomponent, oxyhemoglobin, are both reported.


Significant amounts of free hemoglobin occur in plasma following disruption of the RBC for any reason. This might result from a transfusion reaction or mechanical fragmentation of RBCs due to instrumentation, surgical procedures, or mechanical devices. Patients requiring support from extracorporeal membrane oxygenation or centrifugal ventricular assist devices are commonly monitored for trends in plasma free hemoglobin levels to assess for increasing hemolysis. Sharp spikes in plasma hemoglobin levels can indicate pump disruption. However, plasma hemoglobin can be artifactually increased due to a traumatic blood draw or prolonged exposure to post-draw RBCs. Additionally, bilirubin interferes substantially with the ability to calculate total plasma hemoglobin levels and results may be spurious and unreliable. This is a difficulty frequently encountered in serially tested patients. When this occurs, the oxyhemoglobin level tends to show less interference and will be the only analyte reported in the presence of increased bilirubin (>5 mg/dL). When using trending data, total plasma hemoglobin and oxyhemoglobin levels are not interchangeable and should be compared within their subgroups only.

Reference Values
Describes reference intervals and additional information for interpretation of test results. May include intervals based on age and sex when appropriate. Intervals are Mayo-derived, unless otherwise designated. If an interpretive report is provided, the reference value field will state this.


> or =12 months: 0.0-15.2 mg/dL

Reference values have not been established for patients who are <12 months of age.



> or =12 months: 0.0-12.4 mg/dL

Reference values have not been established for patients who are <12 months of age.

Provides information to assist in interpretation of the test results

An elevation in plasma hemoglobin above the reference range indicates likely intravascular hemolysis due to one of the causes listed in the Useful For section.

Discusses conditions that may cause diagnostic confusion, including improper specimen collection and handling, inappropriate test selection, and interfering substances

Test should not be performed on serum; hemoglobin is liberated from red blood cells during clotting and will falsely increase the result.


Drawing blood specimens for plasma hemoglobin measurement should be done with considerable care to avoid causing hemolysis.


Causes of artifactually increased plasma hemoglobin should be excluded and include: forceful aspiration in sample procurement, cannula malposition (high negative-inflow pressures, inadequate pump speed to blood flow ratio), continuous renal replacement therapy, thrombosis or large hematomas.(1)


Bilirubin is a known interference with this assay. Elevated bilirubin levels significantly interfere with the quantitation of the total plasma hemoglobin. In the presence of elevated bilirubin (>5 mg/dL), only oxyhemoglobin will be reported. Trending data should be compared within analytes (ie, total plasma hemoglobin to total plasma hemoglobin; and oxyhemoglobin to oxyhemoglobin) as these represent different components in the blood. Therefore, in the presence of bilirubin, the trend can only be compared with baseline oxyhemoglobin levels.


If bilirubin is above 5 mg/dL, this comment will be added to the report:

Total plasma hemoglobin not reported due to elevated bilirubin interference. Oxyhemoglobin levels are not affected as significantly by bilirubin levels and are more reliable in this setting. If the plasma hemoglobin test is being utilized in a serial fashion, results should be compared within analyte type (eg, oxyhemoglobin to oxyhemoglobin levels for different time points) and using general trends. Because some variability in this test exists, multiple time points should be used to monitor trends and to confirm wide swings in levels. Because pigmented substances may cause nonspecific interference, clinical correlation is required to establish significance of individual test results.

Clinical Reference
Recommendations for in-depth reading of a clinical nature

1. Lubnow M, Philipp A, Foltan M. et al: Technical complications during veno-venous extracorporeal membrane oxygenation and their relevance predicting a system-exchange-retrospective analysis of 265 cases. PloS One. 2014 Dec 2;9(12):e112316

2. Hayes D Jr, McConnell PI, Preston TJ, Nicol KK: Hyperbilirubinemia complicating plasma-free hemoglobin and antifactor Xa level monitoring on venovenous extracorporeal membrane oxygenation. World J Pediatr Congenit Heart Surg. 2014 Apr;5(2):345-347

Method Description
Describes how the test is performed and provides a method-specific reference

Plasma is examined spectrophotometrically at 8 wavelengths ranging from 415 to 700 nm, and calculations are made that permit quantitation of total heme pigments, oxyhemoglobin, total bilirubin, and methemalbumin, comprising all the frequently encountered plasma pigments. Linearity studies have enabled reporting of values to 2000 mg/dL.(Fairbanks VF, Ziesmer S, O'Brien PC: Methods for measuring plasma hemoglobin in micromolar concentration compared. Clin Chem. 1992 Jan;38(1):132-140; Neal JR, Quintana E, Pike RB, Hoyer JD, Joyce LD, Schears G: Using daily plasma-free hemoglobin levels for diagnosis of critical pump thrombus in patients undergoing ECMO or VAD support. J Extra Corpor Technol. 2015 Jun;47[2]:103-108)

PDF Report
Indicates whether the report includes an additional document with charts, images or other enriched information


Day(s) Performed
Outlines the days the test is performed. This field reflects the day that the sample must be in the testing laboratory to begin the testing process and includes any specimen preparation and processing time before the test is performed. Some tests are listed as continuously performed, which means that assays are performed multiple times during the day.

Monday through Sunday

Report Available
The interval of time (receipt of sample at Mayo Clinic Laboratories to results available) taking into account standard setup days and weekends. The first day is the time that it typically takes for a result to be available. The last day is the time it might take, accounting for any necessary repeated testing.

1 to 3 days

Specimen Retention Time
Outlines the length of time after testing that a specimen is kept in the laboratory before it is discarded

7 days

Performing Laboratory Location
Indicates the location of the laboratory that performs the test


Several factors determine the fee charged to perform a test. Contact your U.S. or International Regional Manager for information about establishing a fee schedule or to learn more about resources to optimize test selection.

  • Authorized users can sign in to Test Prices for detailed fee information.
  • Clients without access to Test Prices can contact Customer Service 24 hours a day, seven days a week.
  • Prospective clients should contact their Regional Manager. For assistance, contact Customer Service.

Test Classification
Provides information regarding the medical device classification for laboratory test kits and reagents. Tests may be classified as cleared or approved by the US Food and Drug Administration (FDA) and used per manufacturer instructions, or as products that do not undergo full FDA review and approval, and are then labeled as an Analyte Specific Reagent (ASR) product.

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 US Food and Drug Administration.

CPT Code Information
Provides guidance in determining the appropriate Current Procedural Terminology (CPT) code(s) information for each test or profile. The listed CPT codes reflect Mayo Clinic Laboratories interpretation of CPT coding requirements. It is the responsibility of each laboratory to determine correct CPT codes to use for billing.

CPT codes are provided by the performing laboratory.


LOINC® Information
Provides guidance in determining the Logical Observation Identifiers Names and Codes (LOINC) values for the order and results codes of this test. LOINC values are provided by the performing laboratory.

Test Id Test Order Name Order LOINC Value
PLHBB Plasma Free Hemoglobin, P 87433-9
Result Id Test Result Name Result LOINC Value
Applies only to results expressed in units of measure originally reported by the performing laboratory. These values do not apply to results that are converted to other units of measure.
31970 Total Plasma Hemoglobin 721-1
31971 Oxyhemoglobin 87437-0

Test Setup Resources

Setup Files
Test setup information contains test file definition details to support order and result interfacing between Mayo Clinic Laboratories and your Laboratory Information System.

Excel | Pdf

Sample Reports
Normal and Abnormal sample reports are provided as references for report appearance.

Normal Reports | Abnormal Reports

SI Sample Reports
International System (SI) of Unit reports are provided for a limited number of tests. These reports are intended for international account use and are only available through MayoLINK accounts that have been defined to receive them.

SI Normal Reports | SI Abnormal Reports

Test Update Resources

Change Type Effective Date
Test Changes - Specimen Information 2022-06-09