Background: Hypercalcemia is a relatively common clinical problem. However, the differential diagnosis between hypercalcemia combined with hyperparathyroidism and a malignant tumor is difficult.
Methods: Appropriate laboratory tests, ultrasound and static imaging of the parathyroid, electronic gastroscopy, and histological examinations were used.
Results: The patient was found to have primary hyperparathyroidism due to hypercalcemia, with a parathyroid adenoma visible on color Doppler ultrasound and PET. The hypercalcemia was corrected after surgical resection. As the symptoms of nausea and vomiting did not improve, further investigations were undertaken, and gastric cancer was found on gastroscopy.
Conclusions: Both primary hyperparathyroidism and gastric tumors may present with symptoms of nausea and vomiting. Clinically, multiple disease possibilities should be considered to explain a particular symptom.