Urine Volume, Color, and Odor

A healthy adult produces between 750 and 2500 ml of urine in a 24 hour period, at an average rate of approximately 25 to 30 ml/hr. Children void smaller quantities than adults, but the total volume voided is greater than adults in proportion to their body size. The amount voided over any period is directly related to the individual's fluid intake, temperature, climactic conditions, and amount of perspiration. Polyuria refers to an increase in the volume of excreted urine. Polyuria is a physiologic response to increased fluid intake, diuretic medications, hypothermia, nervousness or anxiety, large-volume intravenous fluid infusion, or disease conditions such as diabetes mellitus, diabetes insipidus, or renal disease. Oliguria is a term that refers to a decreased urinary output. Anuria refers to a total lack of urine production.

The normal color of urine ranges from light yellow to dark amber, depending on the concentration of solutes in the urine. Urechrome is the name of the pigment that gives urine its characteristic yellow color. Many medications cause the urine to change color. If a patient is taking medications that cause urinary color changes, such as the urinary antiseptic pyridium, which turns the urine a deep orange color, the nurse should make sure the patient knows what color change will occur. The nurse should indicate on the laboratory requisition slip if a patient is taking a medication known to produce a color change in the urine. Foods such as beets or rhubarb may also cause color changes in the urine. Purulent matter gives urine a cloudy appearance, and blood in the urine produces urine that is smoky looking. Bilirubin turns the urine a dark orange that foams on shaking. Nurses may find it useful to consult laboratory or pharmacy manuals and references for a list of drugs that commonly cause urinary color changes.

Urine that has been standing for a period of time at room temperature has a distinct odor. After urine is voided from the bladder, bacteria split urea molecules in the urine into ammonia. If a freshly voided specimen has a foul odor, this may indicate that bacteria are converting urea to ammonia within the bladder, a sign of a urinary tract infection. An unusual or disagreeable odor in freshly voided urine may also be due to drugs or certain foods. For example, asparagus produces a distinct smell in the urine. In some infants, metabolic abnormalities produced by genetic deficits can cause unusual urinary odors.

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The characteristic ammonia smell of standing urine is caused by the splitting of urea by bacteria.