Federal retirees need to be especially careful shopping for health insurance during the current open enrollment period because they have a greater need for health insurance protection than they did when they were younger.

Approximately one in every three retirees will be hospitalized next year, industry statistics indicate. Most retirees will make several visits to doctors in 1986, and the vast majority will be taking some kind of prescription drugs. Added to their special medical problems is the fact that most retirees have less money to spend on premiums or medical care than civil servants.

Between now and Dec. 6 government employes and retirees must pick the health insurance plan they want to cover them for the 1986 year. Premiums next year will drop an average of 8 percent for retirees, so careful shoppers can save hundreds of dollars next year in premiums and out-of-pocket payments by picking the right plan.

On Nov. 4 we listed some of the best insurance buys for the average federal worker, as compiled by Washington Consumer Checkbook magazine. The Checkbook guide ($4.95 at newstands) is especially important for retirees because it has information they cannot readily get from any other source. Federal workers can get copies of insurance plan brochures at the office, but health data is tougher to come by for federal retirees, 100,000 of whom live in this area.

The magazine's "best buy" ratings are based on premiums that workers or retirees would have to pay next year, as well as extra costs for services not covered or covered only in part by the different plans.

For retirees with Medicare coverage, Checkbook recommends that they consider health maintenance organizations (HMOs) that have low premiums and cover prescription drugs, the Blue Cross-Blue Shield standard-option plan, Aetna standard-option plan, the National Alliance of Postal and Federal Employees standard option, Government Employees Hospital Association plan and the Postmasters low-option plan. If they are eligible (former FBI or CIA employes) it also gives high marks to the SAMBA and GEBA plans, to the Foreign Service health plan and the National Association of Postmasters (NAPUS) plan.

For single retirees without Medicare, Checkbook recommends that they consider the Columbia plan, MD/IPA plan, HealthPlus high option, CapitalCare, George Washington University plan, Network plan, Group Health standard option, CHOICE, Kaiser, Group Health high option, HealthPlus standard option, Blue Cross-Blue Shield standard option and Government Employees Hospital Association.

Checkbook estimates that the cost to the retiree next year -- including premiums and out of pocket payments -- will range from $630 for Columbia to $900 for Blue Cross-Blue Shield and GEHA.

Checkbook says that retirees with family plans who don't have Medicare should look at these plans: HealthPlus high option, Columbia, GEHA, Network, Blue Cross-Blue Shield standard option, HealthPlus standard option, MD/IPA, National Association of Letter Carriers plan and CapitalCare. Estimated costs next year, Checkbook says, would range from $1,530 for HealthPlus to $1,790 for the NALC plan.