Getting to know your institution's HIT assays
| Assay type . | What questions should you ask your coagulation laboratory? . | Why is it important to know? . |
|---|---|---|
| Screening assay(s) | Which assay(s) do we use to screen for HIT? | Many options exist. EIAs are the prototypical immunoassay. Rapid immunoassays also exist. |
| What is the sensitivity and specificity of our assay(s)? | Every assay has unique performance characteristics. Understanding the performance characteristics of an assay is essential in clinical risk prediction. | |
| If we have access to an EIA, tell me more about it: Do we report the OD? Is it IgG specific or not? | The likelihood of HIT increases with a higher OD. Specificity is higher with an IgG-only EIA. | |
| What is the turnaround time of our assay(s)? | Some assays take minutes to run; some take hours. Some labs batch samples so results can take days to return. Knowing when to expect results can help inform management. | |
| Functional assay(s) | Which assay(s) do we use? | Options exist, although fewer than screening assays. SRA is considered the “gold standard,” but others exist, including HIPA and PEA. |
| Do we use laboratory techniques to remove any residual heparin from the sample prior to performing the assay? | Residual heparin can interfere with assay performance. If not removed, additional care must be taken to ensure the sample is collected at least 1 hour after heparin is stopped. | |
| What is the sensitivity and specificity of our assay(s)? | Every assay has unique performance characteristics. Even within assay classes, performance can vary by lab. Understanding the performance characteristics of an assay is essential in clinical risk prediction. | |
| What is the turnaround time of our assay(s)? | Most institutions do not run functional assays in-house. Knowing when to expect results can help inform management. |
| Assay type . | What questions should you ask your coagulation laboratory? . | Why is it important to know? . |
|---|---|---|
| Screening assay(s) | Which assay(s) do we use to screen for HIT? | Many options exist. EIAs are the prototypical immunoassay. Rapid immunoassays also exist. |
| What is the sensitivity and specificity of our assay(s)? | Every assay has unique performance characteristics. Understanding the performance characteristics of an assay is essential in clinical risk prediction. | |
| If we have access to an EIA, tell me more about it: Do we report the OD? Is it IgG specific or not? | The likelihood of HIT increases with a higher OD. Specificity is higher with an IgG-only EIA. | |
| What is the turnaround time of our assay(s)? | Some assays take minutes to run; some take hours. Some labs batch samples so results can take days to return. Knowing when to expect results can help inform management. | |
| Functional assay(s) | Which assay(s) do we use? | Options exist, although fewer than screening assays. SRA is considered the “gold standard,” but others exist, including HIPA and PEA. |
| Do we use laboratory techniques to remove any residual heparin from the sample prior to performing the assay? | Residual heparin can interfere with assay performance. If not removed, additional care must be taken to ensure the sample is collected at least 1 hour after heparin is stopped. | |
| What is the sensitivity and specificity of our assay(s)? | Every assay has unique performance characteristics. Even within assay classes, performance can vary by lab. Understanding the performance characteristics of an assay is essential in clinical risk prediction. | |
| What is the turnaround time of our assay(s)? | Most institutions do not run functional assays in-house. Knowing when to expect results can help inform management. |