Blue Cross and Blue Shield of Maryland is seeking 1982 rate increases ranging from 30 to 49 percent for elderly policyholders not covered by group plans, and its counterparts in Virginia and the District of Columbia expect to soon follow suit, company officials said yesterday.

The rate increase requests for policyholders age 65 and over are largely a reaction to the Reagan administration's cutback in Medicare coverage, and appear to be part of a national trend, the officials said. In Maryland, lobbyists for the aged say the increases would have a "very grave impact" on the life styles of the elderly.

"It would not be surprising to see at least a third of our plans make rate increase requests before the end of the year," said Duane Carlson, vice president of the Blue Cross Blue Shield Association in Chicago, which represents 111 companies around the country. "Of course this affects us because it is going to cost us more to provide coverage for older Americans."

Other insurance companies have filed similar requests in Maryland, but none would affect as many people as the proposal by Blue Cross and Blue Shield, which is the largest health insurer in the state, according to Maryland Insurance Commission spokesman Byron Roberts.

Medicare coverage has been steadily reduced over the last five years, but the 1982 cutbacks are by far the largest. Medicare patients, who now pay the first $204 of costs for each 60-day hospital stay, will have to pay $260 starting in January. Blue Cross plans in most states will cover the difference.

In Maryland, a spokesman said, the change will cause the company to lose $12 million in 1982 unless state officials grant the rate increase. Company officials in Virginia and in the District said they face the same problem, and expect to propose rate increases for elderly policyholders effective Jan. 1. They said they will not make their requests public until later this month.

The District-based company, known as Metropolitan Washington Blue Cross Blue Shield, covers persons living in Montgomery and Prince George's counties as well as residents of Alexandria, Arlington and Fairfax.

Blue Cross and Blue Shield plans for Medicare patients vary from state to state. In Maryland, there are two plans for individuals who buy their policies directly, rather than through a group plan. The company is seeking rate increases in both of them, said company spokesman Nicholas Greaves.

Maryland's "65 Program," used by 94,000 people, covers only the hospital costs that Medicare requires elderly persons to pay themselves. The company is seeking to raise its monthly rates from $14.80 this year to $19.20, or 29.7 percent, starting in January. The rates were increased 36 percent this year.

The 48.8 percent request comes in the far more comprehensive Preferred Medicare Supplemental Program, used by 27,000 people. It offers the "65 program" plus substantial additional coverage. The company wants to raise those rates from $33.74 to $50.20 a month, Greaves said.

James Chmelik, assistant director of the state Office on Aging, said that increase alone would consume almost half of the increase that the average Maryland widow will get in her Social Security check this year -- from $313.60 to $348.70 a month.

"Many of these people are going to have to make a decision between insurance and other things -- things like paying rent or basic living costs," he said.