FLT1 and chronic kidney disease: Since the same group subsequently demonstrated that intravenous heparin injection, which was commonly performed before cardiac catheterization, could result in a significant increase in plasma soluble Flt-1 levels and that such increase after heparin injection was markedly blunted in CKD patients [25], the different results between studies in Germany and Japan could be explained by timing of blood collection and sensitivity of endothelium in response to heparin administration.