Washington Real Estate Investment Trust has reported an 8.3 percent increase in fourth-quarter profits and higher earnings for the full year.

The real estate trust earned $795,000 (52 cents a share) in the recent period compared with $730,000 (48 cents) in the last three months of 1977. Rental income from WRIT properties increased 8 percent to $2.5 million, reflecting a 10 percent boost in apartment rentals in D.C. and higher rents from new tenants at a warehouse location in Northern Virginia.

For all of 1978, WRIT earned $2.58 million ($1.70 a share) compared with $2.48 million ($1.66) and rental income increased to $9.3 million from $8.7 million.

WRIT also reported that it renewed the lease for a major distribution center with an 18 percent increase and boosted its dividend rate to 49 cents a share, payable March 30 to owners of record March 5. The new rate combined with an 8-cent boost in December indicates an 8.9 percent increase in the annual payout rate to $1.96 a share.

Capital Mortgage Investors, a real estate investment trust based in Chevy Chase, reported 1978 earnings of $202,366 (12 cents a share), including onetime gains of $2.2 million and after an additional provision of $2.6 million for possible loan losses.

Operating losses for the year were sliced to $2 million from $5.6 million in 1977. The one-time gains reflect exchanges of real estate properaties for cancellation of bank debts.

Government Services Savings and Loan, Inc., of Bethesda, reported record profits for the third quarter ended Dec. 31. Earnings were $694,000 (69 cents) a year earlier. Nine-month profits were up 25 percent to $2.2 million ($2.54 a share) from $1.7 million ($2.03).

President Alexander Boyle said assets were up 9 percent to $319 million and directors approved a quarterly dividend of 12 cents a share, payable Feb. 15 to owners of record Jan. 19.

First Financial of Virginia, a holding company in McLean for Washington-Lee Savings and Loan, reported record profits for the six months ended Dec. 31. Earnings rose 16 percent to $1.16 million ($2.44 a share) from $1 million ($2.11). Directors approved a semi-annual dividend fo 25 cents a share on Jan. 31.