Urine volume measurements are part of the assessment for fluid balance and kidney function. The normal volume of urine voided by the average adult in a 24-hour period (with fluid intake of 2000 mL/d) ranges from 800 to 2000 mL; the typical amount is about 1200 mL. The amount voided over any period is directly related to the individual’s fluid intake, the temperature and climate, and the amount of perspiration that occurs. Children void smaller quantities than adults, but the total volume voided is greater in proportion to their body size.

The volume of urine produced at night is <700 mL, making the day-to-night ratio approximately 2:1–4:1.

Urine volume depends on the amount of water excreted by the kidneys. Water is a major body constituent; therefore, the amount excreted is usually determined by the body’s state of hydration. Factors that influence urine volume include fluid intake, fluid loss from nonrenal sources, variations in the secretion of antidiuretic hormone (ADH), and the necessity to excrete increased amounts of solutes such as glucose or salts. Polyuria is marked increase of urine production (>2.5 L/d). Oliguria is decreased urinary output (<400 mL/d). The extreme form of this process is anuria, a total lack of urine production or <50–100 mL in 24 hours.

Children: 500–1400 mL/24 hr or 1 mL/kg/hr

Adults: 800–2000 mL/24 hr or 1–2 mL/kg/hr

1. Collect a 24-hour urine specimen and keep it refrigerated or on ice.

2. Record the exact collection starting time and collection ending time on the specimen container and in the patient’s healthcare record. Discard first voided urine and include the last voided urine.

3. Transfer the specimen container to the laboratory refrigerator when the collection is completed. Complete the proper forms and document accordingly.

4. Ascertain volume by measuring the entire urine amount in a graduated and appropriately calibrated pitcher or other receptacle. The total volume is recorded as urine volume in milliliters (cubic centimeters) per 24 hours.

1. Polyuria (increased urine output) with elevated blood urea nitrogen (BUN) and creatinine levels

   1. Diabetic ketoacidosis

   2. Partial obstruction of urinary tract

   3. Some types of tubular necrosis

2. Polyuria with normal BUN and creatinine

   1. DM and diabetes insipidus

   2. Neurotic states (compulsive water drinking)

   3. Certain tumors of brain and spinal cord

3. Oliguria (50–400 mL in adults, or <15–20 mL/kg in children per 24 hours)

   1. Kidney causes:

      1. Kidney ischemia

      2. Kidney disease due to toxic agents

      3. Glomerulonephritis

   2. Dehydration caused by prolonged vomiting, diarrhea, excessive diaphoresis, or burns

   3. Obstruction (mechanical) of some area of the urinary tract or system

   4. Cardiac insufficiency

4. Anuria (<50 mL in 24 hours)

   1. Complete urinary tract obstruction

   2. Acute cortical necrosis

   3. Glomerulonephritis (acute, necrotizing)

   4. Acute tubular necrosis

   5. Hemolytic transfusion reaction

Pretest Patient Care

1. Explain purpose of test, procedure for urine collection, and interfering factors.

2. Advise patient to avoid excessive fluid intake and to eliminate caffeine and alcohol. Determine the patient’s usual liquid intake and request that intake not be increased beyond this daily amount during testing.

3. Advise the patient to void salty foods and added salt in the diet.

4. Obtain healthcare provider’s approval to withhold diuretics for 3 days before specimen collection, if possible

5. Follow guidelines in Chapter 1 for safe, effective, informed pretest care.

1. Polyuria

   1. Intravenous glucose or saline

   2. Pharmacologic agents such as thiazides and other diuretics

   3. Coffee, alcohol, tea, caffeine

2. Oliguria

   1. Water deprivation, dehydration

   2. Excessive salt intake