Doc: Listen to your thirst to determine fluid needs
Dear Dr. Roach: We are always being told to drink water — the consequence of which, of course, is increased urination. But what about the kidneys? Since they have to perform repeatedly, are they being worn out prematurely?
I am a 62-year-old female. On my past physical, I was told that my bladder had dropped a bit. Does this have anything to do with excessive urination caused by drinking too much water?
Dear R.R.: The kidney is capable of performing its two primary functions — removing waste products and maintaining salt and water balance — under a wide variety of conditions. In fact, healthy kidneys can get rid of 40 liters of water daily. Even so, a high water load causes the kidney to work hard, especially under the now-rare condition of minimal salt intake. Damaged kidneys sometimes cannot handle a high water load.
I often get frustrated with the recommendation to drink a certain quantity of water, most commonly eight cups a day. That is too much for some people, and not enough for others. Listening to your body and drinking when you are thirsty is, in general, a much better approach. There are some instances where drinking more water than you feel you need makes sense: in people with a history of kidney stones, for example. Some older people have inadequate thirst mechanisms, so an extra glass or two of water might be a good idea for them, and won’t cause problems in most people.
Your second question, about a “dropped” bladder, has nothing to do with the kidneys. Descent of the bladder — a type of pelvic organ prolapse — is caused by changes in the pelvic floor, especially in older women who’ve had multiple childbirths.
Dear Dr. Roach: Should I be concerned with blood tests that show MCV, MCH and mono numbers in the high range?
Dear C.P.: “MCV” is “mean corpuscular volume,” and “MCH” is “mean corpuscular hemoglobin” — indicators of the size of red blood cells. The monocyte (“mono”) is a type of white blood cell.
Large red blood cells happen with deficiencies of vitamin B-12 and folic acid. They also come about with many kinds of uncommon and rare blood diseases. Monocyte levels can be high in infections and certain other kinds of blood diseases.
All that being said, the “normal” range from a laboratory is based on a sample of people in the population. By definition, 5 percent of normal, healthy people will have a lab test result that comes out as abnormal. If you get 15 or 20 lab results, there’s a very good chance that at least one will come out abnormal. Lab tests always must be interpreted keeping the whole situation in mind.
Email questions to ToYourGoodHealth@med.cornell.edu.