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We have selected the following expert medical opinion based on its clarity, reliability and accuracy. Credit: Sourced from the MSD Manual, Consumer Version; authored by Dr Anuja P. Shah (see below). Please refer to your own medical practitioner for a final perspective, assessment or evaluation.
Most people urinate about 4 to 6 times a day, generally in the daytime. Normally, adults pass between 3 cups and 3 litres (quarts) of urine a day.
Excessive urination can refer to:
Urinary frequency may be accompanied by a sensation of an urgent need to urinate (called urinary urgency). Many people particularly notice polyuria because they have to get up to urinate during the night (nocturia). Nocturia also can occur if people drink too much fluid too close to bedtime, even if they drink no more than normal overall.
Some of the causes of increased urine volume differ from those of too-frequent urination. However, because many people who produce excessive amounts of urine also need to urinate frequently, these two symptoms are often considered together.
The most common causes of urinary frequency are:
The most common causes of increased volume or polyuria in both adults and children are:
Diabetes insipidus causes polyuria because of problems with a hormone called antidiuretic hormone (or vasopressin). Antidiuretic hormone helps the kidneys reabsorb fluid. If too little antidiuretic hormone is produced (a condition called central diabetes insipidus) or if the kidneys are unable to properly respond to it (nephrogenic diabetes insipidus), the person urinates excessively.
People with certain kidney disorders (such as interstitial nephritis or kidney damage resulting from sickle cell anaemia) may also urinate excessively because these disorders also decrease the amount of fluid reabsorbed by the kidneys.
Many people are embarrassed to discuss problems related to urination with their doctor. But because some disorders that cause excessive urination are quite serious, people who urinate excessively should be evaluated by a doctor. The following information can help people know when to see a doctor and what to expect during the evaluation.
In people with excessive urination, certain symptoms and characteristics are cause for concern. They include:
People who have leg weakness should go to the hospital immediately because they may have a spinal cord disorder. People who have fever and back pain should see a doctor within a day because they may have a kidney infection. People who have other warning signs should see a doctor within a day or two. People without warning signs should schedule an appointment as soon as is convenient, usually within a few days to a week, although waiting longer is usually safe if symptoms have been developing over weeks or longer and are mild.
Doctors first ask questions about the person's symptoms and medical history and then do a physical examination. What they find during the history and physical examination often suggests a cause of excessive urination and the tests that may need to be done (see section: Some Causes and Features of Excessive Urination).
Doctors ask about:
Some obvious findings may give clues to the cause of frequent urination. Pain or burning during urination, fever, and back or side pain may indicate an infection. In a person who drinks large amounts of beverages that contain caffeine or who has just started treatment with a diuretic, the diuretic substance is a likely cause. A man who has other problems with urination, such as difficulty starting urination, a weak urine stream, and dribbling at the end of urination, may have a prostate disorder.
Some obvious findings may also give clues to the cause of polyuria. For example, polyuria that starts during the first few years of life is likely caused by an inherited disorder such as central or nephrogenic diabetes insipidus or type 1 diabetes mellitus.
Please note: Features include symptoms and the results of the doctor's examination. Features mentioned are typical but not always present.
Cystitis (bladder infection)
Prostate enlargement (benign or cancerous)
Prostatitis (prostate infection)
Stones in the urinary tract (that do not block the flow of urine)
Urinary incontinence
Diabetes mellitus (if uncontrolled)
Diabetes insipidus, central (rare)
Diabetes insipidus, nephrogenic (rare)
Diuretic use
Drinking too much fluid (polydipsia)
Radiation cystitis (bladder damage caused by radiation therapy) (very rare)
In people who have had radiation therapy of the lower abdomen, prostate, or perineum (the area between the genitals and anus) for treatment of cancer
Spinal cord dysfunction or injury (rare)
Doctors do a urinalysis and often urine culture on most people. The need for other testing depends on what doctors find during the history and physical examination (see section: Some Causes and Features of Excessive Urination). If doctors are not sure whether the person is actually producing more urine than normal, they may collect and measure the amount of urine produced over 24 hours. If people actually have polyuria, doctors measure the blood glucose level. If diabetes mellitus is not the cause of polyuria and no other cause, such as excess intravenous fluids, is clearly responsible, other testing is necessary. The levels of electrolytes and concentration of certain salts (osmolarity) are measured in the blood, urine, or both, often after the person is deprived of water for a time and after the person is given antidiuretic hormone.
The best way to treat excessive urination is to treat the underlying disorder. For example, diabetes mellitus is treated with diet and exercise plus insulin injections and/or drugs taken by mouth. In some cases, people can reduce excessive urination by decreasing their intake of coffee or alcohol. Doctors may also adjust the dosage of diuretics that may contribute to excessive urination.
Older men often urinate frequently because the prostate usually enlarges with age. In older women, frequent urination is also more common because of many factors, such as weakening of the pelvic supporting tissues after childbirth and the loss of oestrogen after menopause. Both older men and older women may be more likely to take diuretics, so these drugs may contribute to excessive urination. Older people with excessive urination often need to urinate at night (nocturia). Nocturia can contribute to sleep problems and to falls, especially if a person is rushing to the bathroom or if the area is not well lit.
Dr Anuja P. Shah
MD
Assistant Professor, David Geffen School of Medicine at UCLA, Los Angeles Biomedical Research Institute at Harbor-UCLA Medical Center.
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