Renal function generally is assessed by measurement of GFR and urinary albumin
excretion. Other intrinsic kidney functions, such as proximal tubular secretion, typically are
not quantified. Tubular secretion of solutes is more efficient than glomerular filtration and a
major mechanism for renal drug elimination, suggesting important clinical consequences of
secretion dysfunction. Measuring tubular secretion as an independent marker of kidney
function may provide insight into kidney disease etiology and improve prediction of adverse …