The kidneys typically remove all protein from the blood in processing urine. When the kidneys fail to remove all the protein then some may show up in the urine. A trace amount may not be that unusual but higher amounts could indicate one of several different possible ailments affecting the kidneys. At age 6 kidney disease is usually pretty rare. Hopefully this will be only a trace amount that may warrant a follow up test. If a significant amount is found on a urinalysis dipstick then a quantitative urine collection over 24 hours would be needed. If she has ever had an episode with tea colored urine then this could likely indicate periods of blood in the urine. IgA nephropathy is an immune related disease that might act in such a way.
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Anthony Bray MD