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First-Morning Void uACR Rationale — ESENeph MCQ

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EasyChronic Kidney DiseaseFirst-Morning Void uACR RationaleESENeph

A 50-year-old man with CKD G3b develops new proteinuria. His nephrologist orders a spot uACR and instructs him to provide a first-morning void sample. Why is first-morning void preferred?

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Correct answer: E — First-morning void reduces the effect of orthostatic (postural) proteinuria and exercise-related albumin excretion that can falsely elevate random samples – it provides the most reproducible and representative uACR measurement

First-morning void uACR is recommended by KDIGO 2024 because: (1) it eliminates orthostatic proteinuria (benign proteinuria from prolonged standing that disappears after recumbency – would falsely elevate afternoon samples); (2) it reduces the effect of exercise-related albuminuria; (3) it provides the most concentrated and representative urine sample; (4) it improves day-to-day reproducibility. If first-morning void is not practical, a random spot sample is acceptable but should be interpreted with awareness of these limitations. Dipstick proteinuria should always be confirmed with quantitative uACR.

Reference: KDIGO 2024 – CKD (Albuminuria Section)