Comsat Corp. last week said its profits for the third quarter that ended Sept. 30 were up 140 percent over the same period last year.

The satellite communication firm reported profits of $24 million ($1.31 per share) on revenue of $82.6 million. That compares with earnings of $9.8 million (54 cents) on revenue of $72.8 million for the same period last year.

Comsat lost $51.3 million ($2.80) on revenue of $251.5 million for the nine months, compared with a profit of $37.8 million ($2.06) on revenue of $226.4 million the year before.

Included in the 1987 third quarter was income of $10.7 million related to a favorable resolution of a federal income tax issue. Also included was income from discontinued operations of $3.7 million, primarily from the company's earth station business.

The third-quarter revenue increase was primarily attributed to Comsat Video Enterprises, a wholly owned subsidiary, which started to be reported on a consolidated basis in the second quarter of this year.

Citizens Savings Bank of Silver Spring reported an 11 percent rise in third-quarter earnings.

For the quarter ending Sept. 30, profits were $713,000 (36 cents), compared with $640,000 for the same period a year ago.

For the nine months, net income was $2.4 million ($1.21), compared with $2.1 million the previous year. Earnings per share for 1986 are not meaningful because Citizens converted from mutual to stock ownership in December 1986.