A proposed end to general revenue sharing and a freeze on Medicaid and welfare grants under President Reagan's 1986 budget would cost Washington area jurisdictions millions of dollars and force them to alter their spending plans.

But the region generally would not suffer budget shocks on specific projects and institutions:

* Expansion of the Metro transit system would be funded at $250 million, in line with the transit authority's request, making the area system one of the few in the country to avoid large cuts in construction funds.

* St. Elizabeths mental hospital would get a $67.5 million federal subsidy, as promised in an agreement with the District government last year to phase out the federal role by 1987.

* Spending for operations at National Airport and Dulles International Airport would be reduced from $35.9 million to $35.4 million, and appropriations for construction would be frozen at $13 million.

* The National Zoo would get a new animal hospital building; a permanent vistors center would be built at Arlington National Cemetery, and construction would move forward on the Smithsonian Institution's Center for African, Near Eastern and Asian Cultures.

* Howard University would have federal funding for academic programs frozen at $129.1 million and for the hospital at $22.1 million. It would lose a $5 million research program and a $2 million endowment grant, however. The federal government generally has funded more than 60 percent of the school's academic programs.

* Gallaudet College would receive $58.9 million for its programs, representing a freeze in funding for most programs and with no construction funds budgeted. Federal appropriations in the past have paid for nearly 80 percent of the programs, including elementary and secondary schools, for deaf students.

The District government had earmarked $17.7 million it expected to get in general revenue sharing for police and fire protection, teachers' pensions, general public assistance for disabled workers, mental health services, and bridge and road repairs. The Reagan plan would eliminate general revenue sharing entirely in 1986.

If the president's controversial 5 percent pay cut goes through, it would affect about 350,000 workers in the Washington area. In addition, it would mean a significant reduction in expected income taxes for local jurisdictions.

D.C. Mayor Marion Barry's proposed budget, released on Friday, had assumed a 4 percent pay increase for federal workers as a significant part of its projection that tax revenues would jump by more than $159 million.

D.C. officials have estimated that just a freeze on federal salaries, compared with a 4 percent increase, would "have a serious effect on the Washington area," costing District residents alone $268.8 million in income.

It would reduce the city's income tax projections by $13 million for fiscal 1986, officials estimated.

Reagan's budget includes a federal payment to the city of $425 million, a freeze at last year's level, which is what the city anticipated.

This represents about 19 percent of the city's projected revenues, down from 20.5 percent during fiscal 1985.

The Reagan budget states that "discussions are occurring" between the city and federal governments on creating a formula for determining the annual federal payment to the District, something city officials have wanted for some time to give them more consistency for budget planning.

At a news conference last week, Barry said that District and federal officials now are in philosophical agreement on the need for a formula but still have not agreed on one.

Currently, the federal government picks up half of the cost of local spending on Medicaid and Aid to Families with Dependent Children (AFDC), but Reagan is proposing that this matching system be replaced with a grant frozen at fiscal 1985 levels in 1986 and allowed to rise by an inflation factor only in future years.

"There would be a great incentive to tighten up the rules" on AFDC eligibility if local governments had to pick up 100 percent of any increase in the AFDC roles, said Audrey Rowe, D.C. commissioner on social services.

"People who are on AFDC would be scrutinized more carefully," Rowe said. Currently, the city's caseload is about 24,000, she said.

With health care costs rising faster than inflation, the Medicaid proposals could put a strain on local governments to continue funding current health services for the poor, according to area officials.

H. Louis Stettler III, Maryland secretary of the budget, said the state could lose between $18 million and $20 million in Medicaid funding if the federal government stopped matching expenditures of local governments.

Maryland receives between $90 million and $100 million in general revenue sharing, which is used to benefit low-income areas, so Baltimore would be harder hit by the elimination of the program than other areas, Stettler said.

Gov. Harry Hughes of Maryland just last month proposed increasing welfare grants by 5 percent, but this proposal relied on the federal government picking up half the tab of the increase, about $8 million a year, said William Ratchford II, director of the state's fiscal services department.

One Virginia state budget analyst said the state would lose an estimated $40 million to $50 million in Medicaid funds alone if the president's plan is enacted.

And a committee in the Virginia Senate yesterday reacted to the president's proposed cutbacks by recommending a special fund to help offset some of the impact. Gov. Charles S. Robb last week identified $12 million in excess state revenues, which the committee would put into the contingency fund.

Federal funds make up about 40 percent of the state's budget.

"We want some protection against what the dreadful federal government is going to do," said Sen. Clive L. DuVal II (D-Fairfax).

The Virginia legislature has been working on a plan to increase the state's assistance program for families with dependent children by 12 1/2 percent, and this was estimated to give the average recipient another $30 a month more. With no federal matching for the increase, either the recipients would get less or the state would have to pick up most of the cost.

The District's fiscal 1986 budget assumes that federal funding for human services would rise by $8.3 million to $284.7 million, mainly for Medicaid and AFDC.

Barry's budget included increases in a number of social services and jobs programs but no tax increases.

This contrasted sharply with other recent years when a weak economy and high unemployment forced him to propose some major cutbacks in programs as well as tax boosts.

This year the city expects an "unprecedented" increase in revenues, largely because of the stronger national economy as well as five years of "discipline" in spending and economic development at the local level.

Reagan's budget documents cited the benefits to the state and local governments of the national economic recovery in the explanation of proposals to freeze or cut back on aid to those governments.

The Reagan plan assumes no funding for a special criminal justice and education initiatives added to the District's budget in fiscal 1984 and 1985 by Sen. Arlen Specter (R-Pa.), chairman of the Senate appropriations subcommittee on the District.

This funded construction projects at the D.C. courts and Lorton Reformatory, salaries for seven more D.C. Superior Court judges, a new educational program for District prisoners, a study of merit pay for teachers, a school truancy program and improvements to the parole board.

To continue the initiatives at the current level would require about $16 million, and the mayor did not include funding for this in his budget.

But Specter is expected to push for inclusion of continued federal funding for the programs, which he has been successful at achieving in the past.

Barry said at his news conference that he was not worried about proposed federal budget cuts, however. He said he would wait to see what Congress does to the president's budget before determining the impact to the city.

"We will make those adjustments" if necessary, and the District now has a more sophisticated system than in the past that allows it to adapt more quickly.

Sharp cuts in funding for low-income housing would affect the District, but the city's budget anticipated a cut of $3.9 million in federal housing funds to $67.4 million.

Under the proposal, funding for development projects of the Pennsylvania Avenue Development Corp. would be cut by $1.1 million to $3.25 million.

The National Capital Planning Commission, the central planning agency for the federal government in the region, would receive a small cut of $66,000 in operating funds to $2.6 million.

The budget includes substantial increases for the House and Senate office buildings and lesser ones for the Capitol buildings and grounds.