What creatinine value indicates completeness of a 24-hour urine collection?

• A. < 0.8 g
• B. > 1.2 g
• C. 2.0 g
• D. 0.2 g

Answer: (A)

Urinary creatinine excretion over 24 hours is used to judge whether the collection was complete because creatinine is produced at a relatively constant rate and excreted in urine. In adults, the total daily creatinine excretion typically falls in the range of about 0.8 to 2.0 grams, with exact amounts depending on muscle mass and sex. If the 24-hour collection is complete, the measured creatinine should be within this normal range. Values significantly lower than the lower end (around 0.8 g) suggest that urine was missed or the collection was incomplete, while values within the normal range support completeness.