Not all nighttime urination due to large prostate

DEAR DR. ROACH: I have had nocturia for at least four years. As an example, during a recent, typical night, I had my sleep interrupted five times. The measured urination volume averaged 22 ounces per time. This means, of course, I am dealing daily with notable dehydration.

Two internal medicine docs have shrugged it off. One called it “typical old man syndrome.” (I am a 79-year-old man.)

A urologist checked the physical aspects (pelvic CT, bladder scope and prostate), and found no problems. Then he said, “I can’t help you with your problem.” Also, I understand desmopressin is the only drug sometimes prescribed for nocturia. I asked the urologist about it. He simply said he hadn’t had any luck with desmopressin.

Otherwise, I am healthy, fit and not overweight. I exercise daily.

ANSWER: Urinating at nighttime is one of two general types of problems.

The first category consists of problems with the bladder itself and the collecting system. These generally would be a large number of visits to the bathroom, but small amounts of urine. These kinds of problems often are handled by the urologist, but are not what you are complaining of.

The second type is large amounts of urine at nighttime, called nocturnal polyuria. This can happen in people with heart failure, since the heart is working as hard as it can during the day to keep you going, and it doesn’t have enough flow to provide blood to the kidneys.

At night, during a long rest with no muscle movement, the heart can provide blood to the kidney, and the entire day’s fluid intake comes out at night. This also can happen in people with a lot of fluid in the legs, and in some people with kidney disease as well, for similar reasons.

There are other causes. In diabetics, if the sugar is high at nighttime, some excess sugar and water will be excreted through the kidney. A disease of salt and water balance, diabetes insipidus, can cause a large volume of urine, especially at night. Both Parkinson’s disease and sleep apnea often come with excess urine at night.

However, in your case, none of these seems likely. I often have seen people get into a cycle of increased urination and then overdrinking to compensate, which leads to further urination.

The solution for this is to reduce fluid consumption. You are excreting about three litres during the nighttime alone, and you should try to reduce fluid intake to two litres per day total, with very little taken after 4 p.m.

Doing this slowly allows your kidneys to get used to lower fluid intake and should avoid dehydration (of course, this depends on where you live and what exercise you do).

If this fails, the medication desmopressin (also called ddAVP) is used, but sodium levels need to be followed carefully, and it would be expected to reduce urinating in someone like you from five times per night to three or four.