M Protein Interference in Renal Function Assays: A Quest for True Kidney Function

An 82-year-old woman goes for biannual cardiovascular risk management check-ups at the general practitioner (GP), where her kidney function is evaluated by measuring creatinine (enzymatic assay), from which an estimated glomerular filtration rate (eGFR) is calculated using the Chronic Kidney Disease Epidemiology Collaboration (CKD-EPI) 2009 formula.She has a history of hypertension, reduced left ventricular ejection fraction at 45%, osteoporosis, choledocholithiasis, subclinical hypothyroidism, chronic renal insufficiency, and a monoclonal gammopathy QUESTIONS TO CONSIDER 1. Which renal function assay(s) should be considered when interference by a monoclonal protein is potentially present? 2. Which clinical consequences could be avoided when detection of M protein is timely?3. How can M protein interference in routine clinical chemistry assays be better dealt with in the future?