How do I differentiate between transient and persistent proteinuria in a primary care setting?

To differentiate between transient and persistent proteinuria in a primary care setting:

• Initially, confirm proteinuria using urine albumin:creatinine ratio (ACR) rather than reagent strips, as ACR is more sensitive and specific for proteinuria detection in adults.
• If the initial ACR is between 3 mg/mmol and 70 mg/mmol, repeat the test on a subsequent early morning urine sample to confirm persistence. Persistent proteinuria is confirmed if the repeat ACR remains elevated (≥3 mg/mmol).
• If the initial ACR is 70 mg/mmol or more, no repeat test is needed as this indicates clinically significant proteinuria.
• Transient proteinuria is suggested if the initial positive proteinuria is not confirmed on repeat testing, indicating a temporary or reversible cause.
• Consider clinical context and exclude factors that may cause transient proteinuria such as fever, exercise, or urinary tract infection before confirming persistence.

This approach aligns with NICE recommendations for proteinuria assessment in primary care and helps distinguish transient from persistent proteinuria effectively.

References: NICE NG203