If a fresh urine sample cannot be assayed for creatinine, to what pH should the urine be adjusted?

If a fresh urine sample cannot be assayed for creatinine, to what pH should the urine be adjusted?

• A. 3.0
• B. 5.0
• C. 7.0
• D. 9.0

Answer: (C)

Creatinine in urine remains most stable when the sample isn’t exposed to extreme acidity or basicity. Keeping the urine at around neutral pH minimizes chemical changes or interactions with other urine components that could alter the measured amount by the time the assay is performed. Very acidic conditions (pH 3 or 5) can promote changes in the sample that bias results, while strongly alkaline conditions (pH 9) can also cause interference with the measurement. Neutral pH around 7.0 provides the best balance to preserve creatinine integrity until testing can occur, so that the future assay yields an accurate result.

Creatinine in urine remains most stable when the sample isn’t exposed to extreme acidity or basicity. Keeping the urine at around neutral pH minimizes chemical changes or interactions with other urine components that could alter the measured amount by the time the assay is performed. Very acidic conditions (pH 3 or 5) can promote changes in the sample that bias results, while strongly alkaline conditions (pH 9) can also cause interference with the measurement. Neutral pH around 7.0 provides the best balance to preserve creatinine integrity until testing can occur, so that the future assay yields an accurate result.