Quest Diagnostics, one of the nation's major providers of diagnostic testing services with approximately $11 billion in revenue in 2025 [1], confirmed on Thursday that patient health information and personally identifiable information were accessed in a cybersecurity breach [1]. The New Jersey-based company disabled access to its Quanum Lab Services Manager (LSM) platform after discovering unauthorized access on Wednesday, with expectations to restore full functionality as soon as Friday [1]. The platform allows certain healthcare providers to order laboratory tests and access results [1].
The company stated it believes some patient data was accessed but is still investigating the specific information involved and how many people may have been affected [1]. As a precaution, Quest temporarily paused access to its Essential Insights and LabHQ systems, although it reported no data was accessed on those systems [1]. Despite these restrictions, Quest emphasized that its core business operations remain unaffected and its ability to serve patients has not been materially disrupted [1]. Healthcare providers who normally use Quanum LSM can continue placing orders through paper requisitions or the company's Quanum eLabs platform, with other electronic ordering systems remaining operational [1].
In response to the incident, Quest said it has stopped the unauthorized access and is working to restore the affected system [1]. The company notified federal law enforcement authorities and enlisted outside cybersecurity experts to assist with its investigation and response, as disclosed in a Thursday SEC filing [1]. Quest is working to identify affected patients and healthcare providers and will issue notifications as required by applicable law [1]. This breach follows a previous cybersecurity incident involving a third-party billing provider; in 2019, Quest disclosed that American Medical Collection Agency had reported unauthorized access to a system containing information associated with approximately 11.9 million Quest patients, though Quest's own information technology systems were not involved in that incident [1]. The company has not disclosed whether the latest breach will result in financial consequences [1].
CONCLUSION
Quest Diagnostics faces a significant cybersecurity incident affecting patient data, though the company reports core operations remain unaffected and expects system restoration by Friday. The breach's ultimate financial and reputational impact will depend on the scope of exposed data and regulatory consequences, with the company's stock likely to face pressure until investigation details and affected patient numbers are disclosed.