Endocrine Abstracts

72 years old patient was send to endocrinological outpatients clinic with suspect to nevroendocrine tumor (NET) with chromogranin A (CgA) level 379 μg/l (range 19.4–98.1). She described abdominal colic and diarrhoea lasting 2–3 hours after meals accompanied by dizziness, drenching sweat and lower blood pressure for the last 2 years. Comorbidities: arterial hypertension, chronic gastritis, heart failure and osteoporosis. Medications: omeprazole, losartan, pravastatin, torasemid, acetylsalicylic acid, paracetamol, diclofenac occasionally and ibandronic acid. At inspection clinical status were normal except pain on right abdominal site at deep palpation. Complete blood count, biochemical tests (except creatinine 115 μmol/l, (eGFR 41 ml/min/1.73 m²)) and tumor markers were normal. The hormonal axis of thyroid, glucocorticoid, somatotropic, gonadotropic and prolactin was normal. A pheocromocitoma was excluded. 5-hydroxyindoleacetic acid (5HIAA) levels were elevated (109.0 and 159.2 μmol/l (range 10–47)). Secondary hyperparathyroidism was found and treated. Abdominal US and jejunoileography were normal. The EGDS showed a hiatal hernia. The colonoscopy revealed plain chronic colitis. The endoscopic US revealed 1 cm hyposonic areal in pancreas. Thorax CT, abdominal CT, and MR were normal. Octreoscan and PET-CT were negative. We followed CgA: 543.1, 994.2, 1365 μg/l. No reasonable organic cause for high CgA was found. Additionally, control 5HIAA were in normal range (27.9 and 20.5 μmol/l). The patient was on omeprazole 20 mg/d with a change to pantoprazole 40 mg/d within the 4 month of our evaluation. Pantoprazole was discontinued for 3 weeks and CgA fell to normal range (77.6 μg/l). She was tested with pantoprazole for 2 months and CgA rose to 479.3 μg/l. After discontinuation of proton pump inhibitor (PPI) CgA was again in normal range (66.9 μg/l).

Conclusion: Increase of CgA to such high levels was related to PPI. Control of 5HIAA and all morphological diagnostics were negative. A steep increase of CgA in a relatively short time could show other reasons than NET. Levels of creatinine were stabile. Other possible reasons of falsely elevated CgA are untreated hypertension, glucocorticoid excess, chronic atrophic gastritis, Parkinson disease and presence of heterophile antibodies.