Quest Diagnostics confirmed Thursday that hackers accessed patient health information in a cybersecurity breach that forced the medical testing giant to shut down multiple systems, marking the second major security incident for the company in recent years.
Systems Disabled After Unauthorized Access
The New Jersey-based company discovered unauthorized access Wednesday to its Quanum Lab Services Manager platform, which healthcare providers use to order laboratory tests and access patient results. Quest immediately disabled the system and expects to restore full functionality by Friday. The company also suspended access to its Essential Insights and LabHQ systems as a precautionary measure, though investigators found no evidence of data compromise on those platforms.
Quest filed notice with the Securities and Exchange Commission Thursday, stating that patient health information and personally identifiable information were involved in the breach. The company continues investigating which specific data was accessed and how many patients were affected. Federal law enforcement authorities have been notified, and outside cybersecurity experts are assisting with the investigation and response efforts.
Operations Continue Despite Security Threat
The company reported that core business operations remain unaffected and patient service capabilities have not been materially disrupted. Healthcare providers who normally use the compromised Quanum LSM platform can continue placing orders through paper requisitions or the company’s alternative Quanum eLabs platform. Other electronic ordering systems remain fully operational, and Quest does not anticipate testing delays for clients using different platforms.
Quest stopped the unauthorized access and is working to restore the affected system. The company stated it will identify affected patients and healthcare providers, issuing notifications as required by applicable law. Quest declined to comment on potential financial consequences from the breach.
Pattern of Security Vulnerabilities
This incident follows a 2019 cybersecurity breach involving third-party billing provider American Medical Collection Agency, which potentially exposed personal information of approximately 11.9 million Quest patients. The company emphasized that its own information technology systems were not involved in that earlier incident. Quest Diagnostics, one of the nation’s largest diagnostic testing providers, reported approximately $11 billion in revenue for 2025. The company has not disclosed whether this latest breach will result in financial penalties or regulatory consequences.