Urinary apo(a) excretion is not altered by changes in glomerular filtration rate and renal plasma flow in healthy males.

: Lipoprotein(a) (Lp(a)) is an independent risk factor for atherosclerotic disease. However, information concerning the site of Lp(a) catabolism and breakdown is scarce. Several studies have shown that, in renal insufficiency, plasma Lp(a) levels are elevated, and that after normalisation of kidney function they return to normal. We have recently shown that fragments of apo(a) are found in the urine of healthy individuals. Despite this evidence that apo (a) is excreted into the urine, the mode of excretion of apo(a) remains unclear. Since it has been reported that intravenous infusion of somatostatin can reduce glomerular filtration rate (GFR) and renal plasma flow (RPF), we analysed urinary apo(a) excretion in ten healthy volunteers receiving somatostatin infusions. The infusion of somatostatin led to reversible changes in GFR and RPF. Apo(a) excretion was constant in all 10 individuals over the entire time course when normalised for creatinine. There was a highly significant correlation between plasma Lp(a) levels and urinary apo(a) values. Changes in renal plasma flow and glomerular filtration rate did not alter urinary apo(a) excretion. We conclude that a constant amount of apo(a) is excreted into urine, depending on plasma Lp(a) levels, and that urinary apo(a) excretion is not altered by changes in GFR and RPF in healthy males.