Dr. Michael Fulks, MD, comments on earlier research regarding the relative mortality in apparently healthy adults with various urine protein/creatinine ratios.
As we always search for better testing and risk selection, we should not forget that the simplest (and cheapest) of tests such as looking for proteinuria on urinalysis may still offer the best protection. Anything that damages the vascular tree including hypertension, atherosclerosis and diabetes as well as other conditions associated with mortality risk impact the delicate glomeruli with increased leakage of albumin. Although albuminuria can be tested for more specificity, it makes more sense to screen first for any proteinuria (usually because of excess albumin) and only confirm albumin if needed. It is much less expensive to test for proteinuria rather than albuminuria and the latter screening is so sensitive that it often picks up traces of albumin related to exercise, recent viral infection and other temporary causes, all without mortality risk. Clinical screening for albuminuria (microalbuminuria) requires multiple urinalysis weeks apart with a diagnosis of albuminuria made only if repeatedly positive. This is not possible for insurance testing.
The key to risk control is to use the optimal protein/creatinine (p/c) cut-off values for a positive test for proteinuria which is not the commonly used 0.21 mg/mg of creatinine. That cut-off value was chosen years ago simply based on average 24-hour urine volume and protein excretion rather than any mortality and morbidity analysis. The real screening cut-off should be lower, perhaps as low as 0.11 mg/mg based on CRL research looking at non-diabetic applicants with otherwise normal urine specimens and eGFR when looking at mortality adjusted for age and other parameters. For p/c levels between 0.11 and 0.20 mg/mg, the relative mortality was 160%. For 0.21 to 0.50 mg/mg, the relative mortality was 200% for both younger and older applicants. If albuminuria is not confirmed on reflex albumin testing, risk reverts to normal.
For additional detail and help in deciding how best to use the protein/creatinine ratio, take a look at our Journal of Insurance Medicine article on this subject (Urine Protein/Creatinine Ratio as a Mortality Risk Predictor in Non-Diabetics with Normal Renal Function).
Additional research from industry-leading doctors is available on the CRL website linked here.
About the Author
Michael Fulks, MD, Consulting Medical Director, is board-certified in internal and insurance medicine. After leaving practice, he served as a medical director, creating or editing several underwriting manuals and preferred programs. For the past 13 years, Dr. Fulks has consulted for CRL, participating in its mortality research on individual tests and all laboratory test results, BP and build in combination. He is also involved in the development and implementation of automated screening tools for non-laboratory data.