From the Guidelines
Having 1+ protein in a urine dipstick test but a negative albumin/creatinine ratio warrants further evaluation to determine the cause of the discrepancy, and I recommend repeating both tests in 1-2 weeks, as suggested by the National Kidney Foundation practice guidelines 1. This discrepancy occurs because dipstick tests detect all types of proteins, while the albumin/creatinine ratio specifically measures albumin.
- The protein might be immunoglobulins or other proteins rather than albumin
- You might have had a transient condition like fever, exercise, or dehydration that temporarily increased protein excretion
- There could be a lab error This pattern is generally less concerning than if both tests were positive, but it still warrants follow-up.
- Repeating both tests in 1-2 weeks, ensuring you're well-hydrated and haven't exercised vigorously before the test, can help confirm or rule out the presence of proteinuria
- If the dipstick remains positive, your doctor may order additional tests like urine protein electrophoresis to identify the specific proteins present, as recommended by the National Kidney Foundation 1 While waiting for follow-up, maintain normal hydration and report any symptoms like swelling, foamy urine, or changes in urination to your healthcare provider.
From the Research
Proteinuria and Albuminuria
- Proteinuria is a condition characterized by an excess of protein in the urine, which can be an indicator of kidney damage or disease 2, 3, 4, 5.
- Albuminuria, on the other hand, refers specifically to the presence of albumin, a type of protein, in the urine 2, 4, 5, 6.
Measurement of Proteinuria and Albuminuria
- The protein-to-creatinine ratio (PCR) and albumin-to-creatinine ratio (ACR) are two common methods used to measure proteinuria and albuminuria, respectively 2, 3, 4, 5.
- A spot urine sample can be used to measure PCR and ACR, which can be a convenient and non-invasive alternative to 24-hour urine collection 3, 4, 5.
Comparison of PCR and ACR
- Studies have shown that PCR and ACR are highly correlated, but PCR may be a more sensitive screening test for proteinuria 4.
- ACR, on the other hand, may be a better predictor of long-term renal outcomes in certain conditions, such as IgA nephropathy 5.
- The choice of measurement method may depend on the specific clinical context and the presence of underlying conditions, such as diabetes or hypertension 4, 6.
Clinical Implications
- Proteinuria and albuminuria are important indicators of kidney health, and their measurement can inform diagnosis, prognosis, and treatment decisions 2, 3, 4, 5, 6.
- The use of ACE inhibitors or ARBs is recommended in patients with hypertension and albuminuria, but their utilization may be suboptimal in certain populations 6.