Marked Variation in Serum Chromogranin A Levels in a Patient on Chronic Omeprazole Therapy

Theresa Ratajczak, Ankur Gupta


Serum chromogranin A (CgA) is used as a standard marker in the diagnosis of neuroendocrine tumors. We report a case with wide fluctuation (more than 10-fold) in serum CgA levels in a patient on chronic omeprazole therapy. A 67-year-old woman with hypothyroidism presented for evaluation of facial flushing for 1 year. Flushing had increased in intensity over the past several months without any provocative factors. She denied any diarrhea, wheezing, headache, palpitations or facial erythema. Her home medications were aspirin, omeprazole, levothyroxine, and raloxifene. The patient reported no improvement in flushing on stopping raloxifene. Physical exam was unremarkable. On blood testing, she was noted to have mildly elevated serum CgA of 18.8 ng/mL (range 1.9 - 15 ng/mL). Other endocrine tests including serum tryptase, 24-hour urine N-methylhistamine, 24-hour urine 5-hydroxyindoleacetic acid, metanephrines, catecholamines, and serum calcitonin were unremarkable. Serum CgA was repeated because of her continued symptoms. Repeat blood test showed markedly increased CgA value (128 ng/mL). She underwent a CT chest/abdomen/pelvis and octreotide scan. The octreotide scan showed uptake in the right axillary and subcarinal regions. She subsequently underwent endoscopic bronchial ultrasound and mediastinal biopsy of two lymph nodes. Biopsy was negative for any pathological process. PET scan was done to rule out occult malignancies and was negative. Echocardiogram was normal. She was also seen by neurology with unremarkable workup. CgA levels were repeated over a course of three months and levels varied from 126 to 182 ng/mL. She was asked to hold omeprazole for 2 weeks and CgA levels dropped to 24 ng/mL. The patient resumed omeprazole due to worsening reflux. Repeat CgA level three months later on omeprazole was 18 ng/mL. Venlafaxine and paroxetine were tried for flushing but she could not tolerate these due to side effects. It had been previously established that medications which stimulate neuroendocrine cells, in particular proton pump inhibitors (PPI) could lead to falsely elevated CgA levels. The interesting aspect in this case is increase in CgA more than 10-fold and the marked variation in CgA levels while on omeprazole (18 - 182 ng/mL). There is marked variability in serum CgA levels in presence of a PPI as seen in our case. Clinicians should consider repeat testing of CgA levels in setting of abnormal values and also consider stopping contributing medications before testing and making important clinical decisions.

J Med Cases. 2015;6(5):232-234


Chromogranin A; Proton pump inhibitors; Variation

Full Text: HTML PDF

Browse  Journals  


Journal of Clinical Medicine Research

Journal of Endocrinology and Metabolism

Journal of Clinical Gynecology and Obstetrics


World Journal of Oncology

Gastroenterology Research

Journal of Hematology


Journal of Medical Cases

Journal of Current Surgery

Clinical Infection and Immunity


Cardiology Research

World Journal of Nephrology and Urology

Cellular and Molecular Medicine Research


Journal of Neurology Research

International Journal of Clinical Pediatrics



Journal of Medical Cases, monthly, ISSN 1923-4155 (print), 1923-4163 (online), published by Elmer Press Inc.                     
The content of this site is intended for health care professionals.
This is an open-access journal distributed under the terms of the Creative Commons Attribution-NonCommercial 4.0 International License, which permits unrestricted
non-commercial use, distribution, and reproduction in any medium, provided the original work is properly cited.
Creative Commons Attribution license (Attribution-NonCommercial 4.0 International CC-BY-NC 4.0)

This journal follows the International Committee of Medical Journal Editors (ICMJE) recommendations for manuscripts submitted to biomedical journals,
the Committee on Publication Ethics (COPE) guidelines, and the Principles of Transparency and Best Practice in Scholarly Publishing.

website:   editorial contact:
Address: 9225 Leslie Street, Suite 201, Richmond Hill, Ontario, L4B 3H6, Canada

© Elmer Press Inc. All Rights Reserved.

Disclaimer: The views and opinions expressed in the published articles are those of the authors and do not necessarily reflect the views or opinions of the editors and Elmer Press Inc. This website is provided for medical research and informational purposes only and does not constitute any medical advice or professional services. The information provided in this journal should not be used for diagnosis and treatment, those seeking medical advice should always consult with a licensed physician.