When asked how frequently they urinate, many patients, both men and women explain that during the day, they have no problem but at night, their sleep is repeatedly interrupted by the need to relieve themselves of the urgency of a full bladder. This condition is so common it even has a name, “nocturia” the medical term for getting up from sleep to urinate. There are three distinct types of conditions that can lead to this annoying problem.
The first type includes problems involving the lower urinary tract. These problems may involve the muscles, nerves or other tissues of the bladder, urethra or prostate. Normally, the bladder, slowly and comfortably expands as it gradually fills with urine, accommodating itself to its full normal capacity in adults of about 16 ounces, at which point it sends a signal to the brain that it is full and needs to empty.
During sleep, if the bladder signals that it is full even though it contains less then 16 ounces, the patient will awaken from sleep and head to the toilet. The smaller the bladder capacity, the more often will sleep be disturbed. There are several possible causes of the bladder being unable to expand fully or to signal that it is full when it is not and it is the job of the urologist to determine the specific underlying problem.
The second condition that can result in nocturia is an abnormal increase in the volume of urine produced by the kidneys during the sleeping period. The causes of an increased rate of production of urine include excessive drinking, diuretics, caffeine, alcohol, various drugs, and metabolic problems such as diabetes and high blood calcium or potassium levels.
Swollen legs such as might be due to heart failure, peripheral vascular disease, certain medications or a low blood albumin level also contribute to an increased rate of urine production. Whatever the cause, when the patient lies down in bed, the legs go up on the mattress and the fluid that was trapped in the legs by gravity reenters the circulation, gets filtered by the kidneys and is presented to the bladder as urine. Swollen legs may contain several quarts of fluid and the result of course is nocturia. That is why legs, swollen in the evening usually appear less swollen in the morning.
The third category of conditions that can be associated with nocturia are those related to abnormalities of sleep such as shortness of breath, pain from other causes such as arthritis, insomnia due to depression or the use of various drugs. These are not usually urologic problems although they may present with urologic symptoms. So whether nocturia is related to abnormalities of the lower urinary tract, excessive overnight urine production or sleep-related problems, a careful evaluation of the patient is essential to uncover the cause so proper treatment can be given.
Have a question? Call Dr. Okun at 718-241-6767