Laboratory Corp. of America Holdings (LH) posted a 31% rise in second-quarter profit amid prior-year items as the latest period saw improved margins and higher sales.

Chairman and Chief Executive David King said the company was focusing on maintaining its prices and controlling costs, while building on its position for personalized medicine.

Labcorp, one of the world's largest diagnostic-testing companies, has relied on acquisitions to bolster growth in recent quarters. In June, it agreed to acquire Monogram Biosciences Inc. (MGRM), a maker of products to help guide and improve the treatment of serious diseases.

On Thursday, the company reported earnings of $136.4 million, or $1.24 a share, up from $104.2 million, or 92 cents a share, a year earlier. Excluding restructuring charges and a prior-year bad-debt adjustment, earnings rose to $1.30 from $1.24.

Net sales grew 3.6% to $1.19 billion.

Analysts polled by Thomson Reuters expected per-share earnings of $1.27 on revenue of $1.18 billion.

Operating margins rose to 20.6% from 17%. Labcorp said testing volume increased 2.4%.

The company, which performs routine tests like urinalysis and Pap smears for health-care providers, also projected 2009 results at the high end of its forecast, which excludes Monogram. That deal is expected to close in the third quarter and earnings by 12 cents a share this year.

On Tuesday, Labcorp's main rival, Quest Diagnostics Inc. (DGX), reported its second-quarter profit grew 17% due to improved margins and revenue, leading that company to raise its 2009 earnings forecast.

Labcorp's shares were inactive at $67.81 in premarket trading.

   -By John Kell, Dow Jones Newswires; 212-416-2480; john.kell@dowjones.com