Instrumentation Laboratories Recalls Specific Lots of HemosIL AcuStar HIT-IgG Device Due to Inaccurate Test Results
The FDA announced that Instrumentation Laboratories, also known as Werfen, is removing four specific lots of its HemosIL AcuStar HIT-IgG test from laboratories and distributors. The FDA identified this action as the most serious type of recall because faulty test results could lead to serious injury or death. The medical device is an automated blood test used to help detect antibodies related to heparin-induced thrombocytopenia, a reaction to the blood thinner heparin. Werfen confirmed performance variability showing a negative bias of 20% to 35%, and one customer complaint noted a 47% negative mean bias. This issue can cause a false negative result, which means a doctor might incorrectly think a patient does not have the condition. If a patient with the condition continues to receive heparin, they face a higher risk of dangerous blood clots. As of September 3, 2026, no serious injuries or deaths have been reported from this issue.
What was announced
The U.S. Food and Drug Administration issued a safety alert on October 30, 2026, regarding a recall by Instrumentation Laboratories, which also operates under the name Werfen. The company is pulling four specific lot numbers of its HemosIL AcuStar HIT-IgG(PF4-H) test kits. These lots are B40005, B40006, B38062, and B38063, associated with product numbers 0009800127 and 0009802028.
Werfen asked users to identify and destroy any remaining product from these lots according to facility procedures. They must also record the destruction on a mandatory tracking form. Because of this removal, Werfen expects a supply interruption and instructs laboratories to find alternative testing methods.
What it means
This test is an automated immunoassay, which is a laboratory method that checks blood samples for specific antibodies. Specifically, it looks for IgG antibodies that bind to Platelet Factor 4 when mixed with heparin. Doctors use these results to assess whether a patient has heparin-induced thrombocytopenia, a serious reaction to blood thinners.
Routine quality control checks may fail to catch the defect. Investigation by Werfen showed a systematic negative bias, meaning the test yields lower readings than it should. When results fall below the cut-off value of 1.00 units per milliliter, the device incorrectly labels a sample as negative.
A false negative reading poses severe medical risks. If clinicians believe a patient does not have heparin-induced thrombocytopenia, they may keep administering heparin. Continued exposure to heparin in these patients can trigger dangerous blood clot complications.
What the announcement does not tell us
Werfen stated that its investigation into the root cause of the performance issue is ongoing. The notice does not explain why the defect occurred in these four lots.
It also omits the total number of affected test kits sent to facilities. Healthcare providers are not given a timeline for how long the supply interruption will last or when replacement kits will be ready.
Finally, the document does not direct clinics on whether past patient results must be re-tested. Instead, local facilities and treating clinicians must decide on follow-up steps using their own clinical judgment.
How this was written
This analysis was written with AI from the official announcement below, using only facts that announcement states. The quoted wording is FDA MedWatch Safety Alerts’s own. Always check the original before acting on anything here.
Product performance issue may lead to a false negative result which will delay recognition of heparin-induced thrombocytopenia.
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