Presentation A 15-year-old boy was admitted with a 4-week history of nonbilious, non-bloody emesis 3-4 times a day with progressively decreasing appetite with nausea, fatigue, irritability and 8 kg weight loss. His labs were normal except for BUN 12.1, Creatinine 150, Calcium 4.56 and PTH 157.9. Diagnosis Data was collected from the patient’s medical chart in addition to radiology and histology reports. Treatment Mixed solid and cystic adenoma was treated with a parathyroidectomy. Conclusion Cystic parathyroid adenoma is an important consideration for individuals presenting with unexplained electrolyte imbalance, hyperparathyroidism and hypercalcemia.