A Simple and Inexpensive Way to Predict Microalbuminuria

Lynda Szczech, MD, MSE


June 16, 2014

The Total Urine Protein-to-Creatinine Ratio Can Predict the Presence of Microalbuminuria

Yamamoto K, Yamamoto H, Yoshida K, et al
PLoS One. 2014;9:e91067

Neglecting Proteinuria: Why?

The data are mounting: Proteinuria at any level is associated with an increased risk for morbidity and mortality.[1] The strength of this association surpasses that of both low-density lipoprotein (LDL) cholesterol and blood pressure.[2] Yet, studies in the general practice setting suggest that proteinuria is measured only a fraction of the time, even in patients who are at highest risk for kidney disease.[3]

Among the contributing reasons is probably a lack of clarity on how proteinuria should be measured. Protein in the urine can be measured using a dipstick, a random specimen, or a 24-hour collection. Furthermore, "protein" can be measured as either total protein or as albumin. With 3 methods of measurement of 2 different analytes, there are 6 different ways that some form of proteinuria can be measured.

Contributing to the difficulties in the widespread interpretation of proteinuria are the different thresholds for considering a test abnormal. Regardless of whether a spot urine or 24-hour collection is used, "abnormal" is roughly > 30 mg of albumin excretion or 250 mg of protein excretion.

Without a conversion factor between the 2 tests, how do you know which test to measure? Do you measure both? If you only measure one, which one do you choose? Do you choose one test for low-risk populations and another for higher-risk populations?

An important answer has now been provided, and it's as simple as multiplying by 3 to convert hemoglobin to hematocrit.


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