Heparin-induced thrombocytopenia laboratory findings: Difference between revisions
Jump to navigation
Jump to search
Tarek Nafee (talk | contribs) No edit summary |
Tarek Nafee (talk | contribs) |
||
| Line 3: | Line 3: | ||
==Overview== | ==Overview== | ||
A variety of laboratory tests can be used to aid in the diagnosis of HIT. A complete blood count is always necessary and will show low platelet | A variety of laboratory tests can be used to aid in the diagnosis of HIT. A [[complete blood count]] is always necessary and will show low [[Platelet count|platelet coun]]<nowiki/>t. A high value of the PF4 IgG optical density can suggest HIT. Confirmatory testing is done with the serotonin release assay (SRA), heparin-induced platelet aggregation (HIPA) assay, or other functional assay. These confirmatory tests have high specificity. | ||
==Lab tests== | ==Lab tests== | ||
The most sensitive lab tests are: | The most sensitive lab tests are: | ||
* Complete blood count (CBC): This will show a low [[platelet]] count, (also known as [[thrombocytopenia]]). There is no specific threshold below which HIT is diagnosed, but the typical standard is a decrease in platelet count by approximately 50% or more. | * [[Complete blood count]] (CBC): This will show a low [[platelet]] count, (also known as [[thrombocytopenia]]). There is no specific threshold below which HIT is diagnosed, but the typical standard is a decrease in platelet count by approximately 50% or more. | ||
* Anti-heparin-PF4 IgG: This is a test that employs enzyme-linked immunosorbent assay (ELISA) to detect antibodies against the heparin-PF4 complex. The higher the optical density (OD), the stronger the antibody titer and the higher the likelihood of HIT. | * Anti-heparin-PF4 IgG: This is a test that employs enzyme-linked immunosorbent assay (ELISA) to detect antibodies against the heparin-PF4 complex. The higher the optical density (OD), the stronger the antibody titer and the higher the likelihood of HIT. | ||
| Line 19: | Line 19: | ||
===Serotonin release assay (SRA)=== | ===Serotonin release assay (SRA)=== | ||
* The gold standard is the serotonin release assay (SRA) where antibodies from the patient’s serum result in release of carbon-14 radiolabeled serotonin attached to platelets from a normal patient. | * The gold standard is the serotonin release assay (SRA) where antibodies from the patient’s serum result in release of carbon-14 radiolabeled serotonin attached to [[Platelet|platelets]] from a normal patient. | ||
===Heparin-induced platelet aggregation (HIPA) assay=== | ===Heparin-induced platelet aggregation (HIPA) assay=== | ||
| Line 26: | Line 26: | ||
===Solid-phase immunoassay (SPI)=== | ===Solid-phase immunoassay (SPI)=== | ||
* The SPI is an enzyme-linked immunosorbent assay (ELISA) that tests for the presence or absence of heparin-PF4 complexes. | * The SPI is an [[Enzyme linked immunosorbent assay (ELISA)|enzyme-linked immunosorbent assay]] (ELISA) that tests for the presence or absence of heparin-PF4 complexes. | ||
* As it does not determine whether the antibodies are functionally significant, it is best used in conjunction with one of the two prior tests. <ref>{{cite journal |author=Harenberg J, Huhle G, Giese C, Wang L, Feuring M, Song X, Hoffmann U |title=Determination of serotonin release from platelets by enzyme immunoassay in the diagnosis of heparin-induced thrombocytopenia |journal=Br J Haematol |volume=109 |issue=1 |pages=182-6 |year=2000 |pmid=10848798}}.</ref> <ref>Hirsh J, Dalen JE, Deykin D, Poller L. Heparin: mechanism of action, pharmacokinetics, dosing considerations, monitoring, efficacy, and safety. Chest 1992; 102:337S-351S. PMID 1327666</ref> <ref>Walenga JM, Bick RL. Heparin-induced thrombocytopenia, paradoxical thromboembolism, and other side effects of heparin therapy. Med Clin North Am 1998; 82:635-58. PMID 9646784</ref> <ref>Fabris F, Luzzatto G, Stefani PM, Girolami B, Cella G, Girolami A. Heparin-induced thrombocytopenia. Haematologica 2000 Jan; 85:72-81. PMID 10629596</ref> | * As it does not determine whether the antibodies are functionally significant, it is best used in conjunction with one of the two prior tests. <ref>{{cite journal |author=Harenberg J, Huhle G, Giese C, Wang L, Feuring M, Song X, Hoffmann U |title=Determination of serotonin release from platelets by enzyme immunoassay in the diagnosis of heparin-induced thrombocytopenia |journal=Br J Haematol |volume=109 |issue=1 |pages=182-6 |year=2000 |pmid=10848798}}.</ref> <ref>Hirsh J, Dalen JE, Deykin D, Poller L. Heparin: mechanism of action, pharmacokinetics, dosing considerations, monitoring, efficacy, and safety. Chest 1992; 102:337S-351S. PMID 1327666</ref> <ref>Walenga JM, Bick RL. Heparin-induced thrombocytopenia, paradoxical thromboembolism, and other side effects of heparin therapy. Med Clin North Am 1998; 82:635-58. PMID 9646784</ref> <ref>Fabris F, Luzzatto G, Stefani PM, Girolami B, Cella G, Girolami A. Heparin-induced thrombocytopenia. Haematologica 2000 Jan; 85:72-81. PMID 10629596</ref> | ||
Latest revision as of 19:07, 18 August 2017
|
Heparin-induced thrombocytopenia |
|
Differentiating Heparin-induced thrombocytopenia from other Diseases |
|---|
|
Diagnosis |
|
Treatment |
|
Case Studies |
|
Heparin-induced thrombocytopenia laboratory findings On the Web |
|
American Roentgen Ray Society Images of Heparin-induced thrombocytopenia laboratory findings |
|
Heparin-induced thrombocytopenia laboratory findings in the news |
|
Blogs on Heparin-induced thrombocytopenia laboratory findings |
|
Directions to Hospitals Treating Heparin-induced thrombocytopenia |
|
Risk calculators and risk factors for Heparin-induced thrombocytopenia laboratory findings |
Editor-In-Chief: C. Michael Gibson, M.S., M.D. [1]; Associate Editor-In-Chief: Cafer Zorkun, M.D., Ph.D. [2], Aric C. Hall, M.D., [3] Shyam Patel [4]
Overview
A variety of laboratory tests can be used to aid in the diagnosis of HIT. A complete blood count is always necessary and will show low platelet count. A high value of the PF4 IgG optical density can suggest HIT. Confirmatory testing is done with the serotonin release assay (SRA), heparin-induced platelet aggregation (HIPA) assay, or other functional assay. These confirmatory tests have high specificity.
Lab tests
The most sensitive lab tests are:
- Complete blood count (CBC): This will show a low platelet count, (also known as thrombocytopenia). There is no specific threshold below which HIT is diagnosed, but the typical standard is a decrease in platelet count by approximately 50% or more.
- Anti-heparin-PF4 IgG: This is a test that employs enzyme-linked immunosorbent assay (ELISA) to detect antibodies against the heparin-PF4 complex. The higher the optical density (OD), the stronger the antibody titer and the higher the likelihood of HIT.
The most specific tests are:
- Serotonin release assay (SRA)
- Heparin induce platelet aggregation (HIPA) assays
- Solid-phase immunoassay (SPI) (H-PF4 enzyme-linked immunosorbent assay [ELISA])
- Particle gel immunoassay (PIFA)
These specific tests are used for confirmatory testing for HIT after the initial PF4-IgG test is found to be high. The sensitivity of these confirmatory tests, however, is 94% at best.
Serotonin release assay (SRA)
- The gold standard is the serotonin release assay (SRA) where antibodies from the patient’s serum result in release of carbon-14 radiolabeled serotonin attached to platelets from a normal patient.
Heparin-induced platelet aggregation (HIPA) assay
- The HIPA assay is done via a light transmission aggregometer.[1] It is performed by mixing platelet-poor plasma from a patient with suspected HIT with platelet-rich plasma from donors.
- It has a >90% specificity but is limited by low sensitivity.
Solid-phase immunoassay (SPI)
- The SPI is an enzyme-linked immunosorbent assay (ELISA) that tests for the presence or absence of heparin-PF4 complexes.
- As it does not determine whether the antibodies are functionally significant, it is best used in conjunction with one of the two prior tests. [2] [3] [4] [5]
If HIT is suspected it may take hours to days to obtain the laboratory back. In the meantime it may simply be a safer approach to substitute another agent (eg agatroban) for heparin.
Reference
- ↑ Harenberg J, Marx S, Krejczy M, Wehling M (2012). "New anticoagulants - promising and failed developments". Br J Pharmacol. 165 (2): 363–72. doi:10.1111/j.1476-5381.2011.01578.x. PMC 3268190. PMID 21740405.
- ↑ Harenberg J, Huhle G, Giese C, Wang L, Feuring M, Song X, Hoffmann U (2000). "Determination of serotonin release from platelets by enzyme immunoassay in the diagnosis of heparin-induced thrombocytopenia". Br J Haematol. 109 (1): 182–6. PMID 10848798..
- ↑ Hirsh J, Dalen JE, Deykin D, Poller L. Heparin: mechanism of action, pharmacokinetics, dosing considerations, monitoring, efficacy, and safety. Chest 1992; 102:337S-351S. PMID 1327666
- ↑ Walenga JM, Bick RL. Heparin-induced thrombocytopenia, paradoxical thromboembolism, and other side effects of heparin therapy. Med Clin North Am 1998; 82:635-58. PMID 9646784
- ↑ Fabris F, Luzzatto G, Stefani PM, Girolami B, Cella G, Girolami A. Heparin-induced thrombocytopenia. Haematologica 2000 Jan; 85:72-81. PMID 10629596