Federal Realty Investment Trust elected Steven J. Guttman yesterday to be a managing trustee, repalcing Samuel J. Gorlitz, who will become one of five trustees.

Gorlitz, a co-founder of the Washington-based REITZ 17 years ago along with Daniel M. Lyons, said he planned to continue his interest in the trust.

Gorlitz told an annual meeting of stockholders that the plans to open an office for real estate consulting. He said that he and Lyons, both former State Department ecomomists, had been partners and business associates for 25 years.

Guttman, 32, who had been serving as chief operating officer since 1976, said that the trust's assets increased by nearly $10 million in 1978 with the acquisition of three shopping centers wiht more than 400,000 square feet of leaseable space and now stand at $40 million. One, Pimmit Hills in the Falls Church area, will be expanded and renamed Tyson Station later this year. The other reccently acquired properties are in Dover, Del., and Springfield, III.

Federal Realty properties now include 13 moderately sized shopping centers with a total of 1.8 million square feet of space and five apartment projects with a total of 1,074 rental units.

Guttman also told a stockholders' meeting that Federal Realty has contracts to buy six other shopping centers, probably later this year, from Amterre Development Inc. and has an option on a seventh. The properties are in Southeastern Pennsylvania and New Jersey. They have more than a million square feet of space and are valued at more than $16 million, he added.

In reviewing the Federal Realty portfolio, Guttman said that the large holdings in shopping centers are a "hedge against inflation" and that apartments have a potential value for future condominium conversion beyond the book value of $10,000 a unit.

Federal Realty owns the Continental (360 units) in Suitland, the Rollingwood (282) in Silver Spring, the Pines (182) in Gaithersburg, the Park Maple (137) in Takoma Park and the Broadfalls (113) in Falls Church.

With Lyons and Guttman now actively running Federal Realty as managing trustees, FRIT also has four relected trustees, in addition to Gorlitz. They are Arnold M. Kronstadt, Donald H. Misner, Robert A. Philipson and William C. Yowell. After serving for 17 years, Henry J. Fox did not seek re-election.

Federal Realty's report on its first quarter cash flow showed a 26 percent increase in revenue to $2.2 million and a net cash flow of $491,253 from operations, up 6 percent. However, net operating income declined 11 percent to $349,594, and pershare income fell 17 percent to 24 cents. CAPTION: Picture 1, Samuel J. Gorlitz; Picture 2, Steven J. Guttman: change at Federal Realty.