Renal Function Immunoassay Tests

Precision testing for renal health

Overview

Renal Function impairment

Several assays are available for use on the Optilite® analyzer to assess kidney function, and detect proteinuria, using serum and urine samples.

Kidney function can be assessed by using markers such as creatinine to calculate the estimated Glomerular Filtration Rate (eGFR).

Proteinuria is the presence of excess proteins in urine and can be assessed by performing several urine tests. Undetected proteinuria may mean underlying kidney damage is not identified. This may mean that irreversible kidney damage can occur, leading to kidney failure.

Renal impairment in Multiple Myeloma(MM):

  • Renal impairment ([eGFR] of <60 ml/min/1.73 m2) is a common and potentially serious finding in multiple myeloma (MM)
  • Newly diagnosed MM patients with renal impairment have inferior survival rates
  • Early diagnosis and prompt treatment of renal impairment due to cast nephropathy caused by multiple myeloma is critical since the window of opportunity for reversing it is very limited.
  • Patients with severe acute kidney injury (AKI) of unknown cause should be screened for monoclonal gammopathy in case this is the underlying cause of the kidney injury.
Several assays available on the Optilite® Analyser can be used to assess kidney function, and detect proteinuria, using serum and urine samples

Renal Funtion assessment

Why choose cystatin measurement OVER creatinine when calculating estimated glomerular filtration rate?

Assessment of renal function is vital in Multiple Myeloma (MM) patients. This is often done by estimating glomerular filtration rate (eGFR).  This calculation can use creatinine or Cystatin C values in the estimate. Use of creatinine in the calculation may underestimate the extent of kidney disease in patients with MM, which can affect treatment doses and toxicity.

Compared to creatinine, Cystatin C test is a more sensitive marker for renal filtration and is unaffected by age, gender, or race1,2. The use of Cystatin C to calculate eGFR instead of creatinine may help avoid underestimating kidney disease in MM patients, particularly among women.

A recent study in newly diagnosed patients with MM [24 women / 37 men, mean age of 68 (±11)] investigated different equations used for the evaluation of eGFR, and compared them with the reference method to identify the most sensitive equation for detection of kidney disease, and to identify patients with more risk factors.3

The study concluded that inclusion of Cystatin C values in equations such as CKD-EPI and CAPA are more accurate when detecting hidden kidney disease, as well as patients with more and worse prognostic factors.

There is evidence that Cystatin C is superior to creatinine when calculating eGFR for patients with MM

Cystatin C – Recommended for the assessment of patients with Multiple Myeloma

National Kidney Foundation – American Society of Nephrology  (NKF-ASN) recommendations: 

A joint task force of NKF- ASN recommended immediate implementation of CKD-EPI creatinine equation; issued a report aiming at suppressing race adjustments in eGFR calculations, and stressing that Cystatin C-based calculations do not include such bias4

 

  • β2 microglobulin is a low molecular weight protein found on the surface of most nucleated cells
  • It is excreted only in trace amounts in the urine. However, in tubulo-interstitial disorders, excretion of this protein increases markedly. Thus, urinary β2-microglobulin measurement is a valuable tool for associated with tubulo-interstitial renal damage
  • Optilite β2 microglobulin urine kit is used for quantitative determination of beta-2 macroglobulin in urine samples. This aids in the diagnosis of active rheumatoid arthritis and kidney disease
  • β2-microglobulin levels in serum are typically raised in renal disease and rheumatoid arthritis.
  • Elevated serum levels are also observed in Inflammatory conditions and haematological malignancies.
  • Optilite β2 microglobulin kit is used for quantitative determination of beta-2 macroglobulin in serum samples. This aids in the diagnosis of active rheumatoid arthritis and kidney disease. 
Freelite® Assays
Product
Freelite® Assays

Detect and Monitor Multiple Myeloma with Freelite® assays
Optilite® Analyser
Product
Optilite® Analyser

The Optilite Analyser utilises proven turbidimetric technology which is known to be fast, robust and versatile, becoming the main technology for protein diagnostics worldwide
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References
1. LATERZA OF, PRICE CP, SCOTT MG. CYSTATIN C: AN IMPROVED ESTIMATOR OF GLOMERULAR FILTRATION RATE? CLIN CHEM 2002;48:699-707.
2. INKER LA, ENEANYA ND, CORESH J, TIGHIOUART H, WANG D, SANG Y, ET AL. NEW CREATININE- AND CYSTATIN C-BASED EQUATIONS TO ESTIMATE GFR WITHOUT RACE. N ENGL J MED 2021;385:1737-49.
3. Cepeda-Piorno et al. Cystatin C-Based Equations Detect Hidden Kidney Disease and Poor Prognosis in Newly Diagnosed Patients with Multiple Myeloma. Adv Hematol 2022
4. Delgado C et al. A Unifying Approach for GFR Estimation: Recommendations of the NKF-ASN Task Force on Reassessing the Inclusion of Race in Diagnosing Kidney Disease. Am J Kidney Dis. 2022;79(2):268-288.e1.