Congress may take action this year to help the District overcome a "shocking" high-school dropout rate, Rep. Julian C. Dixon (D-Calif.), chairman of the House Appropriations subcommittee on the District, said yesterday.

The actual high-school dropout rate is in dispute, with the D.C. schools estimating it at 17 percent and the D.C. Department of Human Services, in a justification of its budget for youth services programs, estimating it at 32 percent after the 10th grade.

"That the DHS figure is a shocking statistic, if true . . . . I'm concerned about it," Dixon said yesterday after a hearing on the District's fiscal 1986 budget. He said when the hearings continue in June he will ask DHS officials how they arrived at the figure.

Dixon said the subcommittee "would like to assist" Superintendent Floretta McKenzie in reducing the dropout rate, and he said he would talk with her first about developing plans for attacking the problem. "I'm not saying just throw more money at it," he added.

The school system recently created an "attendance center," using federal funds appropriated for the current fiscal year, which counsels students with poor attendance records. McKenzie said in testimony Wednesday that that program also will reduce dropouts.

The U.S. Department of Education offers a third estimate of the city's dropout rate, saying it is 44.2 percent, the highest in the country. Those figures were not discussed at yesterday's hearing.

McKenzie has said the Education Department's figures are based on false assumptions and do not take into account students who left school because they moved out of the District. The school system's dropout figures do not include any of those who moved out, because the city cannot track them to see if they are attending school elsewhere, she said.

Dixon, whose subcommittee reviews and can amend the city's budget, said the only other area of concern he sees in the District's fiscal 1986 spending plan is the set-aside of only $5 million toward paying off the accumulated general fund deficit, which stood at $270 million at the end of fiscal 1984.

Congress in the past has insisted on the city's paying off more than that, last year imposing a $20 million level of repayment for fiscal 1985.

In other testimony, Office of Cable Television officials said yesterday that cable construction should begin in early 1986 and cable should be available in some homes in the District by late 1986.