CgA₁₀₀ - eGFR-adjusted serum chromogranin A

Area of Science:

• Biochemistry
• Clinical Chemistry
• Nephrology

Background:

• Serum chromogranin A (s-CgA) is a widely used biomarker for neuroendocrine neoplasms.
• Elevated s-CgA levels can occur in conditions unrelated to neuroendocrine tumors, notably renal failure.
• Accurate interpretation of s-CgA requires accounting for patient renal function, but standardized methods are lacking.

Purpose of the Study:

• To develop and validate a formula for adjusting serum chromogranin A (s-CgA) levels based on estimated glomerular filtration rate (eGFR).
• To provide a method for standardizing s-CgA measurements, improving diagnostic accuracy in patients with varying renal function.

Main Methods:

• Developed an adjustment formula using multivariable fractional polynomial quantile regression on data from 2708 patients.
• The model correlated median s-CgA with sex, age, and eGFR, using the CgA II KRYPTOR assay.
• The formula s-CgA100 = (eGFR / 100) × s-CgA was derived and tested on an independent cohort (n=1563) using a RIA method.

Main Results:

• A simplified adjustment formula, s-CgA100, was developed to normalize s-CgA values to an eGFR of 100 mL/min/1.73 m².
• The adjusted s-CgA100 values were found to be independent of eGFR in an independent validation cohort.
• No adjustment was applied for patients with eGFR > 100 mL/min/1.73 m².

Conclusions:

• The developed s-CgA100 formula provides a method to correct for the influence of renal function on serum chromogranin A levels.
• This standardization may enhance the reliability of s-CgA as a biomarker for neuroendocrine neoplasms across different patient populations.
• Further clinical investigations are needed to confirm the clinical utility and impact of s-CgA100.