Serum Indoxyl Sulfate ELISA Kit (IS)

Full Name: Serum Indoxyl Sulfate ELISA Kit (IS)
Reactivity: Human
Sample Type: Plasma, Tissue Homogenates, Serum, Biological Fluids
Sensitivity: 0.469 ng/ml


Indoxyl sulfate (IS) is a toxin found in patients, with kidney disease (CKD) that builds up in the body due to kidney function. It is produced when the gut bacteria metabolize tryptophan from the diet and is normally eliminated by the kidneys. However, in CKD as kidney function declines IS levels increase, which can be harmful and worsen the progression of the disease.

The concentration of indoxyl sulfate rises as kidney function deteriorates. Can serve as a marker for CKD progression. In stages of CKD, an imbalance in gut bacteria. Weakened intestinal barrier function lead to increased production of IS. As CKD advances further decreased filtration and impaired secretion result in the retention of IS. The levels of indoxyl sulfate are inversely related to the estimated filtration rate.

High levels of IS have been associated with effects in patients with CKD including cardiovascular diseases, bone disorders, inflammation, and poor outcomes. The toxic effects of IS include dysfunction of blood vessel lining cells, calcification within blood vessels, platelet aggregation leading to clotting issues, enlargement of heart muscle cells (cardiomyocyte hypertrophy) inhibition of bone forming cells (osteoblasts) oxidative stress induction and promotion of inflammatory signaling molecules called cytokines. Lowering serum levels of IS through methods such as adsorbents or interventions like prebiotics or probiotics could potentially provide benefits for individuals, with CKD.


Human serum indoxyl sulfate ELISA kit can measure concentrations of IS (indoxyl sulfate , serum indoxyl sulfate) present is plasma, serum, biological fluids or tissue homogenate samples.


All reagents supplied need to be stored at 2 °C – 8 °C, unopened reagents will retain reactivity until expiration date. Do not use reagents beyond this date.

  • One 96-Well Plate: Pre-coated with anti-IS antibody.
  • Standards: Lyophilized recombinant.
  • Sample/Standard Dilution Buffer.
  • Biotinylated-labelled Antibody.
  • Antibody Dilution Buffer.
  • HRP-Streptavidin Conjugate (SABC).
  • SABC Dilution Buffer.
  • TMB Substrate.
  • Wash Buffer (25x).
  • Plate Sealer.
  • Product Instructions.


For this serum indoxyl sulfate ELISA kit, it is recommended that a standard curve is generated for each assay carried out.

Standard Curve: 0, 0.781, 1.562, 3.125, 6.25, 12.5, 25, 50 ng/ml.
Reactivity: Human
Sensitivity: 0.469 ng/ml
Range: 0.781 – 50 ng/ml
Principle: Competitive, Coated with Antigen
Application: Research Use Only.


– Specificity: Highly specific for IS, no cross reactivity or interference between IS and analogues was detected.
– Recovery: Serum (91 – 103%), EDTA Plasma (87 – 105%), Heparin Plasma (91 – 102%).
– Linearity: Serum (85 – 105%), EDTA Plasma (89 – 101%), Heparin Plasma (85 – 94%).
– Precison Intra-Assay: CV < 8%
– Precison Inter-Assay: CV < 10%


  1. Serum indoxyl sulfate is associated with mortality in hospital-acquired acute kidney injury: a prospective cohort study. BMC Nephrol. (2019) 20 (1): 57. Wang W., et al.
  2. Early elimination of uremic toxin ameliorates AKI-to-CKD transition. Clin Sci (Lond). (2021) 135 (23): 2643-2658. Chen J.H., et al.
  3. Serum Concentration of Indoxyl Sulfate in Peritoneal Dialysis Patients and Low-Flux Hemodialysis Patients. Blood Purif. (2019) 48 (2): 183-190. Xie T., et al.
  4. Serum concentrations of free indoxyl and p-cresyl sulfate are associated with mineral metabolism variables and cardiovascular risk in hemodialysis patients. J Nephrol. (2022) 35 (5): 1457-1465. Arcidiacono T., et al.


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