Suburban Bancorporation, holding company for Suburban Trust Co. of Hyattsville and Thurmont Bank, yesterday reported an 11 per cent increase in fourth-quarter profits but a 5 per cent decline for the full year.

Virginia National Bank-shares, meanwhile, reported a sharp fourth-quarter gain in profitability and innounced that total assets of the Norfolk-based bank holding company have topped $2 billion for the first time.

At Suburban, fourth-quarter earnings totaled $2.9 million (65 cents a cents) compared with $2.6 million (60 cents) a year earlier, not counting gains or losses from selling securities. Profits for the full year dipped to $10.3 million ($2.36 a share) compared with $10.9 million ($2.49) in 1975.

Holding company president Robert F. Tardio said the final quarter gains resulted partially from lower interest costs, including a 68 per cent reduction in the average level of higher-cost certificates of deposit from the same period in 1975.

Lower profits for the full year were due mainly to lower commercial loan volume and interest rates and higher non-interest expenses. Total assets were $928 million on Dec. 31 compared with $949 million a year earlier but loan volume rose 9.6 per cent to $537 million.

Virginia National Bankshares reported operating profits in the fourth quarter of $3.3 million (74 cents a share), up 37 per cent from $2.4 million (54 cents) in the 1975 period.

For the full year, VNB operating profits showed a modest gain of 3.5 per cent to $12.5 million ($2.78) from $12.1 million (2.69), while net income (counting securities transaction) rose by 7.3 per cent to $12.3 million ($2.74) from $11.5 million ($2.55).

Chairman W. Wright Harrison said that the past year was "difficult," with earnings adversely affected by recession, Loans in default and real state held for resale totaled about $45 million on Dec. 31, down 14 per cent from $52 million a year earlier, Harrison said.

Citizenz Bank and Trust Co. of Maryland reported 1976 operating profits of $6.5 million ($6.53 a share) compared with $6.2 million ($6.21) a year earlier. Deposits on Dec. 31 were $391 million, a gain of $25 million over the end of 1975. The Riverdale-based bank operates 44 offices and will open three more in the near future in Townson, Pikesville and White Flint Mall on Rockville Pike.

Arlington Trust Co., which operates 15 offices in Fairfax and Arlington counties, reported 1976 profits of $2.4 million ($6.89 a share) compared with $2.27 million ($6.52) in 1975. Deposits rose to $225 million from $208 million.

McCormick & Co., the Baltimore spice manufacturer, reported a decline in fourth-quarter profits and a slight gain for the full year, ended Nov. 30.

Fourth-quarter net income was $4.6 million (88 cents a share) vs. $5.9 million ($1.14) as sales rose to $97.4 million from $81.7 million. For the year, profits totaled $11.6 million ($2.22) on sales of $304 million vs. profits of $11.1 million ($2.14) and sales of $251.3 million in 1975.

First Maryland Bancorp a Baltimore-based bank holding company whose principal subsidiary is First National Bank of Maryland, reported that 1976 profits were the second highest in the firm's 170-year history. Not counting securities transaction, earnings totaled $10 million ($3.37 a share) compared with $10.3 million ($3.45) in 1975; net income rose slightly to $3.38 a share from $3.37.

Ryland Group, a homebuilder based in Columbia reported a 91 per cent gain in profits last year to $4.7 million ($1.80 a share) compared with $2.5 million (97 cents) in 1975. Fourth-quarter profits were $1.3 million (51 cents) vs. $974,000 (38 cents).