Quantifying the Effects of Renal Impairment on Plasma Concentrations of the Neuroendocrine Neoplasia Biomarkers Chromogranin A, Chromogranin B, and Cocaine- and Amphetamine-Regulated Transcript

To the Editor:Neuroendocrine neoplasia (NEN)1 accounts for 2% of all malignancies (1). Patients with NEN often present with nonspecific symptoms and thus represent a major diagnostic challenge. There are several circulating NEN biomarkers, and chromogranin A (CgA) is regarded as the gold standard (2). Chromogranin B (CgB) has been found to be a useful diagnostic addition to CgA measurements (3). The peptide product of cocaine- and amphetamine-regulated transcript (CART) is also increased in patients with NENs, particularly in those with pancreatic NENs (4).Renal impairment or failure can increase circulating concentrations of CgA (2) and CART (4); however, CgB may be unaffected by mild renal impairment and is increased only in severe renal failure (3). The population most likely to be affected by NEN is also susceptible to renal impairment: Chronic kidney disease (CKD) occurs in approximately 10% of the population between 50 and 60 years of age, and the mean age of patients with a NEN diagnosis is 61 years (1, 5). We therefore examined the effect of varying degrees of renal impairment/failure on plasma concentrations of CgA, CgB, and CART in patients without NEN.Ethics approval for this study was obtained from the Hammersmith and Queen Charlotte's and Chelsea Hospitals Research Ethics Committee (04/Q0406/80). After informed written consent was obtained, 5 mL of blood was collected from 40 healthy volunteers. In addition, samples from 107 patients with different stages of renal impairment were obtained and irreversibly anonymized as per Royal College of Pathology, UK, guidelines (D035, September 2007). All blood samples were collected into EDTA-containing tubes and centrifuged at 10 000 g for …