In orthostatic proteinuria, when is a 24-hour urine collection indicated?

In orthostatic proteinuria, when is a 24-hour urine collection indicated?

• A. Always
• B. Only if the first-morning void is elevated
• C. Never
• D. If proteinuria persists beyond one year

Answer: (B)

Orthostatic proteinuria is a benign pattern in which protein in the urine rises with upright posture during the day and returns to normal when lying down at night. The first-morning urine, collected after a night of recumbency, is typically free of protein. If that morning sample is elevated, it suggests protein excretion is not solely due to upright posture, so a 24-hour urine collection is needed to quantify total daily protein and assess for persistent or non-orthostatic proteinuria. If the morning void is normal, a 24-hour collection is usually not required because the daytime proteinuria can be explained by upright posture consistent with orthostatic proteinuria.

Orthostatic proteinuria is a benign pattern in which protein in the urine rises with upright posture during the day and returns to normal when lying down at night. The first-morning urine, collected after a night of recumbency, is typically free of protein. If that morning sample is elevated, it suggests protein excretion is not solely due to upright posture, so a 24-hour urine collection is needed to quantify total daily protein and assess for persistent or non-orthostatic proteinuria. If the morning void is normal, a 24-hour collection is usually not required because the daytime proteinuria can be explained by upright posture consistent with orthostatic proteinuria.