A letter from a 65-year-old reader says:

"Young people like you might not be interested inthis, but for me it is a serious problem.

"It is necessary for me to visit my doctor every three weeks. Because I am now living on Social Security. I thought that Medicare would be picking up all or most of my doctor bills. I was wrong.

"My doctor charges $15 for an office visit, but Medicare considers $10 to be the 'usual' fee, and it pays only 80 percent of that. So I am reimbursed only $8 for each $15 I pay out.

"I hesitated to mention this to my doctor because from what I hear from my friends, $15 is considered a very reasonable fee these days. Finally, however, I did mention it to him.

"The doctor explained that Blue Shield uses a formula for determining what is usual.' He said that in large part it depends on what the doctor used to charge, how long ago he raised his fees, and so forth.

"The doctor said to me, 'I guess they still have in their "profile" on me the fact that many years ago I charged $3 for an office an office visit. But for heaven's sake, I have been practicing for 40 years, and in that time everything has gone sky high -- my rent, my office help, my medical supplies, everything.'

"Then he added a wry comment that really summed it up. He said, 'My son went into practice last year and began charging $25 a visit. Blue Shield accepted that as his normal fee. He had never charged anything less than $25, so that's his profile and his patients are reimbursed 80 percent of $25 while mine are held to 80 percent of $10.'

"I ask you, Bill, does this make sense to you? Is this system really fair?"

No, young man, it does not make sense to me, but I know how you feel because I am four years older than you and have encountered the same situation.

I was interested to note that the federal government has canceled its contract with D.C. Blue Shield for the processing and payment of Medicare claims here. After Oct. 1, claims will be handled by another firm that will do the work cheaper.

Washington Post staff writer Jack Eisen reported recently that the cancellation will cost Blue Shield about $5 million in fees for processing about $100 million in claims each year.

I doubt very much whether the switch to a new processing firm will mean that claimants will receive a more realistic ruling on what is normal or "usual" in medical fees these days. Don't get your hopes up.

It is clear that the Social Security system must begin taking in more money or paying out less.

But nobody dares suggest another increase in Social Security taxes, and there is little support on Capitol Hill for the suggestion that Social Security deficits be financed from the general fund. So you can see where that leaves us.

I agree that a "profile" formula based on ancient history is not fair, but this is a bad time to be asking for increased reimbursement.

For those who are not required to live on Social Security benefits, Medicare payments based on profiles are not a great hardship. But if I had to live on a Social Security check when I retire, I'm sure that I, too, would be asking: Is this really the most equitable way to deal with this problem?