Urinalysis and Body Fluids 6th Edition by Majorie DiLorenzo, Susan Strasinger

Exercise 7

A patient brings a 24-hour timed specimen to the laboratory and reports that he or she forgot to collect a specimen voided during the night.

a. How will this affect the results of a quantitative test for creatinine?

b. What should the patient be told to do?

Step 1 of 2

a.

24-hour timed specimen:

• The collection should be done with an empty stomach

• Collection container, and preservative is provided to the patient

• Day 1- 6am: Patient voids urine, and discard the specimen, collects urine for next 24 hours

• Day 2-6am: Patient voids, and urine is mixed to previously collected urine

• When arrived at laboratory the 24 hour specimen is well mixed, the volume is measured, and recorded

Creatinine concentration changes with diurnal variations. Hence, 24 hour collection is suitable for creatinine measurement.

Therefore, failure to collect the urine at night in 24-hour timed specimen, creatinine concentration results is falsely decreased.