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  5. N Latex Cystatin C Assay

N Latex Cystatin C AssayAssay for Early Detection of Decline in Renal Function

N Latex Cystatin C Assay

N Latex Cystatin C Assay

Renal disease often progresses undetected, because kidney impairment does not cause pain. This is why chronic kidney disease is not diagnosed until patients show symptoms of an advanced stage of the disease. In the early stages of disease, laboratory testing is the most efficient and sensitive way to detect reduction in renal function.1

Cystatin C shows increased sensitivity to renal dysfunction compared to serum creatinine, especially in the early stage of kidney disease characterized by a mild reduction in glomerular filtration rate.

The N Latex Cystatin C Assay:

  • Is suitable for both serum and plasma specimens
  • Has low imprecision (total CV <5%)
  • Runs on the Atellica® NEPH 630 System2, BN™ II System, and BN ProSpec® System

Features & Benefits

Cystatin C is a nonglycated, low-molecular-weight (13 kDa) protein that is synthesized by all nucleated cells. It is produced at a constant rate regulated by a housekeeping gene.3 Cystatin C is freely filtered by the glomerulus, and there is no tubular secretion or any extrarenal elimination. In addition, cystatin C is not affected by muscle mass, diet, gender, or inflammation.

The relevance of determining cystatin C for diagnosis in CKD is included in the international KDIGO (Kidney Disease Improving Global Outcomes) guidelines.4

No tubular secretion; sensitive in the creatinine-blind range3

  • Higher sensitivity in early disease

Independent of age, sex, and muscle mass3

  • Constant relationship between cystatin C and glomerular filtration rate (GFR) at 1 year of age and older
  • Single reference range: 0.62–1.11 mg/L in children and adults ranging in age from 1 to 78 years
  • Sensitive detection of declining GFR with aging
  • Reliable in patients with spina bifida, paralysis, amputations, etc.

High correlation to GFR reference methods3; high correlation to GFR decline

  • High reliability and accuracy

Increased sensitivity compared to creatinine in liver disease patients5 or by creatinine intake. Cystatin C levels may be influenced by high-dose steroid therapy or thyroid dysfunction.

No analytical interferences known

 

Technical Details

Assay characteristics

Assay principle

Latex-enhanced immunonephelometry

Sample type

Serum, lithium-heparinized plasma

Sample Volume

30 uL

Time to First Result

6 minutes

Initial Sample Dilution

1:100 (auto-dilution)

Standard Dilutions

1:20 to 1:640 (auto-dilution)

Initial measuring range

0.27 – 9.4 mg/L

Minimum measuring range

0.06–1.9 mg/L

Reference range

0.62–1.11 mg/L

Antigen Excess Security

No hook effect up to 42.91 mg/L

Reagent Onboard Stability

5 days at 8 hours each (BN II System)
4 weeks (BN ProSpec and Atellica NEPH 630 System2)

Standardization

ERM-DA471/IFCC

1

Levey AS, Coresh J, Balk E, et al. National Kidney Foundation Practice Guidelines for Chronic Kidney Disease: Evaluation, classification, and stratification. Ann Intern Med. 2003;139:137-47.

2

Not available for sale in the U.S. Product availability varies by country.

3

Newman DJ. Cystatin C. Ann Clin Biochem. 2002;39:89-104.

4

KDIGO 2012 Clinical Practice Guideline for the Evaluation and Management of Chronic Kidney Disease. Official Journal of the International Society of Nephrology. 2013;3:1-5.

5

Woitas RP, Stoffel-Wagner B, Flommersfeld S, et al. Correlation of serum concentrations of cystatin C and creatinine to inulin clearance in liver cirrhosis. Clin Chem. 2000;46:712–15

The products/features (mentioned herein) are not commercially available in all countries. Due to regulatory reasons their future availability cannot be guaranteed. Please contact your local Siemens Healthineers organization for further details.