Chronic kidney disease (CKD) often results from hypertension or diabetes. When the kidneys are damaged, the filtration function is blocked, then the wastes and the uremic toxins accumulate in the circulation. Among all uremic toxins, protein-bound toxins such as indoxyl sulfate (IS) are critical to CKD patients. When the glomerular filtration rate decreases, protein-bound toxins become challenging to be cleared in the blood and further damage the renal function and cardiovascular system. Indoxyl sulfate (IS) is a good marker for CKD diagnosis since it directly reflects the glomerular filtration rate. We have a breakthrough in discovering an antibody against the small molecule. And we have launched the CE marked LEADGENE® Indoxyl Sulfate (IS) ELISA Kit.