CHARLOTTE, N.C. (AP) _ A North Carolina hosiery firm has gone to new heights to test its hiking and mountaineering socks - the Andes Mountains.

Thor-Lo, a division of Statesville-based Thornesburg Hosiery Co., was the corporate sponsor of the American Andes Biomedical Research Expedition to several Peruvian mountain peaks - including 22,205-foot-high Mount Huascaron.

While other participants such as NASA and New York University Medical Center conducted physical tests on climbers, Thor-Lo provided socks to be used in its own testing.

''I'm a little tired but I loved it,'' said Michael Shadroui, Thor-Lo's national field coordinator, who returned home last week after climbing 19,000- foot Mount Pisco.

''My previous high climb was 14,000 feet,'' Shadroui said in a telephone interview Tuesday from the company's office. ''The last 5,000 feet was a revelation.''

The expedition, which began June 4 and still is under way, was sponsored primarily by New York University Medical Center. Medical research conducted during the climb included field tests for NASA and Walter Reed Army Hospital.

Among the 17 climbers in the expedition were Dr. William Bernhard, of NYU Medical Center; Col. Thomas Mader, of the Madigan Army Medical Center in Tacoma, Wash.; and Col. Lawrence Mohr, the White House physician.

Areas of study included altitude mountain sickness, hypobaric hypoxia, and brain response time at high altitudes, Shadroui said.

Thor-Lo became involved in the expedition after a conversation six months ago between Bernhard and Jim Thornesburg, president of the privately-held hosiery company, Shadroui said.

Thor-Lo usually tests its products in the field with fitness buffs, hikers, members of the ski patrol and long distance runners, according to Enid Walker, the company's director of communications.

Thornesburg decided the Peruvian expedition was an excellent opportunity to conduct tests on the company's hiking and mountaineering socks. Each climber was given a set of socks for testing of moisture management, abrasion, and thermal quality.

''The temperatures ranged from 85 degrees during the day to sub-zero at nights,'' said Shadroui, who also participated in a barrage of tests conducted by the medical teams.

Results of Thor-Lo's own tests won't be known for some time, Shadroui said, and much of the information will remain secret for competitive reasons. Based on the reaction of his fellow climbers, the company's products apparently held up well under tough conditions.

''Dr. Bernhard said he'd never been on an expedition with fewer foot problems,'' Shadroui said.