DEAR DR. DONOHUE: I suppose when you get older, you can expect lots of things. I am in my mid-80s, and I am having a terrible time sleeping at night. My main complaint is frequent urination. I am up at all hours. I can live with that. My main concern is the ankle swelling I have every morning. Can the swelling and the urination problem be related? - Mrs. V.R.

ANSWER: Let's talk generally about the daytime ankle swelling. That is fluid accumulation. At night, when you lie down, that fluid oozes out of tissue around your ankles and back into blood circulation. The gravity that kept it in the ankles during the day when you were up and around is no longer in the picture. The ankle swelling goes down.The frequency of nighttime urination is related to this redistribution of fluid. The kidneys, recognizing that there is more fluid back in circulation, acts to get rid of it. That's what gets you up.

But I can't leave things here. At your age, one must consider specific contributing factors, such as heart involvement. If it isn't pumping as strongly as it should, the body will retain too much fluid. Again, the pattern of swelling and frequent urination can result. There are today many medicines to restore heart pumping strength, and one of them might be all you need.

I'm giving you only one possible setting for such problems. If you were a man, I would have to include prostate enlargement as a possibility.

-Dr. Donohue welcomes reader mail but regrets that, due to the tremendous volume received daily, he is unable to answer individual letters. Readers' questions are incorporated in his column whenever possible.