NEW YORK (Reuters) - Lab testing company Quest Diagnostics Inc said on Thursday it will cut 400 to 600 jobs by the end of 2013 as part of its effort to reduce costs by $500 million.

The job cuts, which will save $65 million, are part of a restructuring in which the company will have only two divisions, Quest said in a statement. That change is due to take place by January 1, 2013.

The company will take an additional $15 million to $20 million in charges to cover the costs of reducing management layers, which will include the departure of senior leaders.

Quest's growth has slowed in 2012 as the economy and uncertain reimbursements have resulted in fewer lab tests. The company has 42,000 employees.

(Reporting by Caroline Humer; Editing by Jeffrey Benkoe)