Creatinine normalization is used to adjust for what condition in urine testing?

• A. Urine color
• B. Temperature
• C. Urine dilution
• D. pH

Answer: (C)

Creatinine normalization adjusts for how concentrated or dilute urine is. Creatinine is produced at a fairly steady rate by muscle metabolism and is excreted in urine at a relatively constant rate, so its urine concentration serves as a reliable proxy for urine dilution. By expressing a drug metabolite level relative to creatinine (for example, per creatinine amount), you reduce the impact of hydration differences on the measured concentration, allowing more accurate comparisons between samples. Urine color, temperature, and pH do not reliably reflect dilution and can vary for reasons unrelated to how concentrated the urine is, so they aren’t used for this purpose.