A medical laboratory company based in New Jersey said Monday that it was investigating a recent hack that exposed the personal health information of about 34,000 people.

An “unauthorized third party” gained access to names, dates of birth, lab results and, in some cases, telephone numbers on Nov. 26 through a mobile health app that gives patients access to lab results and other information, according to the company, Quest Diagnostics, which is based in Madison, N.J.

The stolen data did not include Social Security or credit card numbers or any other insurance or financial information. All the people affected have been notified, the company said. It also said there was no indication that any of the information had been misused.

The company did not say whether the hack affected individuals in any particular region of the country. The company has locations throughout the United States.