Some diseases or conditions require a second morning specimen or a 2-hour or 24-hour urine specimen to evaluate kidney function accurately (see Table 3.2). Substances excreted by the kidney are not excreted at the same rate or in the same amounts during different periods of the day and night; therefore, a random urine specimen might not give an accurate picture of the processes taking place over a 24-hour period. For measurement of total urine protein, creatinine, electrolytes, and so forth, more accurate information is obtained from a long-term specimen. All urine voided in a 24-hour period is collected into a suitable receptacle; depending on the intended test, a preservative is added, the collection is kept refrigerated, or both (Table 3.3).
In a healthcare facility, responsibility for the collection of urine specimens should be specifically assigned.
When instructing a patient about 24-hour urine collections, make certain the patient understands that the bladder must be emptied just before the 24-hour collection starts and that this preliminary specimen must be discarded; then, all urine voided until the ending time is saved.
Do not predate and pretime requisitions for serial collections. It is difficult for some patients to void at specific times. Instead, mark the actual times of collection on containers.
Documentation of the exact times at which the specimens are obtained is crucial to many urine tests.
Instruct the patient to urinate as near to the end of the collection period as possible.
When a preservative is added to the collection container (e.g., HCl preservative in 24-hour urine collection for vanillylmandelic acid [VMA]), the patient must take precautions against splashing or spilling the contents and receiving an acid burn. Provide instructions regarding spillage before the test begins.
The preservative used is determined by the urine substance to be tested for. The laboratory usually provides the container and the proper preservative when the test is ordered. If in doubt, verify this with the laboratory personnel.
Ask the patient to void at the beginning of a 24-hour timed urine specimen collection (or any other timed specimen collection). Discard this first specimen and note the time.
Mark the time the test begins and the time the collection should end on the container. As a reminder, it may be helpful to post a sign above the toilet (e.g., “24-Hour Collection in Progress”), with the beginning and ending times noted.
Collect all urine voided over the next 24 hours into a large container (usually glass or polyethylene) and label it with the patient’s name, the time frame for collection, the test ordered, and other pertinent information. It is not necessary to measure the volume of individual voidings, unless specifically ordered.
Ask the patient to void 24 hours after the first voiding to conclude the collection. Add urine from this last voiding to the specimen in the container.
Storage:
Keep nonrefrigerated samples in a specified area or in the patient’s bathroom.
Refrigerate the collection bottle immediately after the patient has voided or place it into an iced container if refrigeration is necessary.
Because the patient may not always be able to void on request, the last specimen should be obtained as closely as possible to the stated end-time of the test.
Pretest Patient Care
Most 24-hour urine specimen collections start in the early morning at about 7:00 a.m. (0700). Instruct the patient to do the following:
Empty the bladder completely on awakening and then discard that urine specimen. Record the time the voided specimen is discarded and the time the test is begun.
Save all urine voided during the next 24 hours, including the first specimen voided the next morning.
Add the urine voided the next morning (as close to the ending time as possible) to the collection container. The 24-hour test is then terminated, and the ending time is recorded.
Use a urinal, wide-mouth container, special toilet device, or bedpan to catch urine. It is probably easier for women to void into another wide-mouth receptacle first and then to transfer the entire specimen carefully to the collection bottle.
It is most important that all urine be saved in the 24-hour container. Ideally, the container should be refrigerated or placed on ice.
Test results are calculated on the basis of a 24-hour output. Unless all urine is saved, results will not be accurate. Moreover, these tests are usually expensive, complicated, and necessary for the evaluation and treatment of the patient’s condition.
If the laboratory requests an aliquot, record total amount, mix well, and aliquot the requested amount.
Always check with your laboratory as to the preservative needed; different laboratories may have different requirements.
Follow guidelines in Chapter 1 for safe, effective, informed pretest care.
Posttest Patient Care
Review test results; report and record findings. Modify the nursing care plan as needed.
Follow guidelines in Chapter 1 for safe, effective, informed posttest care.
Failure of patient or attending personnel to follow the procedure is the most common source of error.
The patient should be given both verbal and written instructions. If the patient is unable to comprehend these directions, a significant other should be instructed in the process.
If required, the proper preservative must be used.
Instruct the patient to use toilet paper after transferring the urine to the 24-hour collection container. Toilet paper placed in the specimen decreases the actual amount of urine available and contaminates the specimen.
The presence of feces contaminates the specimen. Patients should void first and transfer the urine to the collection receptacle before defecating.
If heavy menstrual flow or other discharges or secretions are present, the test may have to be postponed, or an indwelling catheter may need to be inserted to keep the specimen free of contamination. In some cases, thorough cleansing of the perineal or urethral area before voiding may be sufficient. If in doubt, communicate with laboratory personnel and the healthcare provider who ordered the test.