Quest Diagnostics says hackers got into a lab ordering system and patient records were likely exposed. Here is who should pay attention and what to watch for.
Quest Diagnostics, one of the biggest lab testing companies in the country, says someone broke into one of its online systems and that patient records were likely compromised. The company found the problem on October 21, 2026, and told the U.S. Securities and Exchange Commission (SEC) the next day.
The system involved is called Quantum Lab Services Manager. Certain clients, such as medical practices, use it to order tests and look up results. Quest says the incident appears limited to that system. It has not said what kinds of patient information were involved, and it does not yet know how many people are affected.
No hacking group has claimed responsibility so far. Quest says it moved to contain the activity and has put fixes in place to stop more unauthorized access. Outside cybersecurity experts are helping, and federal law enforcement has been notified.
The people most at risk are patients of clinics and practices that use this ordering system. If your doctor sends your blood work or other tests to Quest, it is worth asking whether the office uses it. Quest has not published a list of affected clients.
Quest is huge. It serves about one-third of adult Americans and has around 2,000 patient service centers. But only certain customers use this system, so the breach is unlikely to match its last big one. That one came through a billing vendor between August 2018 and March 2019 and exposed about 11.9 million patients. Quest also says its ability to serve patients and run its business has not been affected.
The alert box above lists the steps. The short version is to watch for a notice, stay alert to scam messages and check your bills and insurance statements. Stolen health details can make a scam call sound believable, so be careful with anyone who mentions your tests.
Quest has temporarily paused access to the system while it investigates. Clients can still order tests and get results by fax, on paper, or through direct connections to their own record systems. The company says it will share more as the investigation moves forward. Until then, the number of patients and the type of data involved remain unknown.
If your doctor uses Quest, watch for a breach notice, check your medical bills and insurance statements, and distrust any message that mentions your lab tests.
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