Marked Variation in Serum Chromogranin A Levels in a Patient on Chronic Omeprazole Therapy
Bibliographic record
Abstract
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 doi: http://dx.doi.org/10.14740/jmc2135w
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How this classification was reachedexpand
Full frame machine prediction
Teacher imitationNot calibrated prevalence, not ground truth. Human validation pending. The Gemma side is a direct model label for every work in the frame, read from the title-only record. The Codex side is a classifier learned from the 10,348 direct Codex labels and calibrated to design-weighted sample rates; fields without enough sample support carry no Codex call. Candidate is the union of the two sides; consensus is their intersection. These outputs are machine_predicted_unvalidated and are not human labels.
Distilled classifier scores by category (both heads)
| Category | Codex | Gemma |
|---|---|---|
| Metaresearch | 0.000 | 0.001 |
| Meta-epidemiology (narrow) | 0.001 | 0.000 |
| Meta-epidemiology (broad) | 0.001 | 0.001 |
| Bibliometrics | 0.001 | 0.001 |
| Science and technology studies | 0.001 | 0.001 |
| Scholarly communication | 0.001 | 0.001 |
| Open science | 0.000 | 0.000 |
| Research integrity | 0.001 | 0.001 |
| Insufficient payload (model declined to judge) | 0.001 | 0.000 |
Machine scores (provisional)
The two teacher heads of the student model, read on this work. A score orders the frame for review; it never asserts a category, and the validation status ships verbatim with every row.
Baseline scores from an immature model (maturity gate not passed, 7 training rounds). Scores rank; they never assert a category.
score_only:v0-immature-baseline · verbatim from the scoring run: score_only means the number may rank works, and no category label ships from itClassification
machine, unvalidatedMachine predicted; a candidate call from one source (direct Gemma or distilled Codex), not a consensus.
How this classification was reached, model by model and score by score, is at the end of the page under "How this classification was reached".