24-hour urine protein
24-hour urine protein measures the amount of protein excreted in urine over a 24-hour period.
How the test is performed
A 24-hour urine sample is needed. The health care provider will instruct you, if necessary, to discontinue drugs that may interfere with the test.
- On day 1, urinate into the toilet when you get up in the morning.
- Afterwards, collect all urine in a special container for the next 24 hours.
- On day 2, urinate into the container when you get up in the morning.
- Cap the container. Keep it in the refrigerator or a cool place during the collection period. Label the container with your name, the date, the time of completion, and return it as instructed.
Thoroughly wash the area around the urethra. Open a Urine collection bag (a plastic bag with an adhesive paper on one end), and place it on the infant. For males, the entire penis can be placed in the bag and the adhesive attached to the skin. For females, the bag is placed over the labia. Diaper as usual over the secured bag.
This procedure may take a couple of attempts - lively infants can displace the bag, causing the specimen to be absorbed by the diaper. The infant should be checked frequently and the bag changed after the infant has urinated into the bag. The urine is drained into the container for transport to the laboratory.
Deliver it to the laboratory or your health care provider as soon as possible upon completion.
How to prepare for the test
No special preparation is necessary for this test, but if the collection is being taken from an infant, a couple of extra collection bags may be necessary.
How the test will feel
The test involves only normal urination, and there is no discomfort.
Why the test is performed
The test determines the amount of protein that is excreted in the urine in 1 day.
Normally, less than 150 milligrams of protein per day (or 10 milligrams per deciliter) is excreted in the urine. The proteins are derived from plasma and the urinary tract. The most common urine protein in normal individuals is Tamm-Horsfall protein, a glycoprotein that is secreted by distal tubular cells.
Smaller quantities of albumin and globulins are also present in the urine. Most of the filtered proteins are normally reabsorbed by the proximal tubular cells of the kidney.
The normal value is less than 150 mg/day, or less than 10 mg/dl. Normal value ranges may vary slightly among different laboratories.
Note: mg/day = milligrams per day; mg/dl = milligrams per deciliter (of urine)
What abnormal results mean
Increased urinary protein is usually measured when glomerular disease is suspected. The deterioration in the integrity of the glomerulus allows albumin to permeate in large quantities. Glomerular disease, such as nephrotic syndrome may result in urine protein (mostly urine albumin) of greater than 3.5 gm/day. So-called microalbuminuria with urine albumin levels of 30 to 200 mg/day is considered an early sign of diabetic nephropathy.
Renal tubular diseases usually have urine protein levels in the range of 1 to 2 gm/day. In this case, most of the protein is represented by low-molecular weight globulins that would be reabsorbed by normal tubules. Diseases that fall into this category include: pyelonephritis, Fanconi’s syndrome, cystinosis, and Wilson’s disease.
Overflow protein in the urine results from the presence of greater than normal levels of protein in the plasma, as with Bence-Jones proteinuria, which is present in Multiple Myeloma, Waldenstrom’s macroglobulinemia, and some lymphomas. The Bence-Jones protein (quantitative) test detects proteins that are light chains of immunoglobulins.
Additional conditions under which the test may be performed include complicated UTI (pyelonephritis).
Note: gm/day = grams per day; mg/day = milligrams per day
What the risks are
There are no risks.
Healthy people may exceed normal protein excretion levels after strenuous exercise or with dehydration. Some foods may affect protein levels.
Drugs that can cause increased excretion levels include acetaminophen, antibiotics, gentamicin, and non-steroidal anti-inflammatory drugs (when associated with analgesic nephropathy).
by David A. Scott, M.D.
All ArmMed Media material is provided for information only and is neither advice nor a substitute for proper medical care. Consult a qualified healthcare professional who understands your particular history for individual concerns.