When Common Isn’t Typical: A Diagnostic Twist in Hyperparathyroidism
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Publication Date
4-29-2026
Keywords
oregon, psvmc, psvmc gme, psvmc oaa
Disciplines
Medical Education
Abstract
Introduction: Primary hyperparathyroidism is the third most common endocrine disorder, following diabetes and thyroid disease. It is characterized by excess calcium and inappropriately elevated parathyroid (PTH) levels. Severe disease classically presents with a combination of nephrolithiasis, bone pain, osteoporosis, constipation, abdominal pain, anxiety, depression, or confusion. However, due to the availability of routine labs, most cases now present as asymptomatic hypercalcemia. Case Description: A 60-year-old female was evaluated for falls, generalized weakness, constipation, and brain fog. Her admission labs revealed a calcium of 19.6 mg/dL and subsequent PTH of 1,932 pg/mL. She was treated with intravenous fluids, pamidronate, and cinacalcet, and ultimately required hemodialysis for calcium normalization. A CT of the neck and chest showed a nodule at the right tracheoesophageal groove and another nodule adjacent to the left thyroid gland, both suggestive of parathyroid adenomas. However, two right lung masses, concerning for malignancy, were also identified. In the setting of extreme hypercalcemia, a CT-guided lung biopsy was performed due to suspicion for parathyroid carcinoma or ectopic PTH-secreting lung cancer. Lung pathology revealed benign hamartoma. Subsequent right parathyroidectomy was performed, and pathology was most consistent with a parathyroid adenoma. The PTH level normalized intraoperatively, and she was discharged to a skilled nursing facility. Discussion: Hypercalcemia has an expansive differential diagnosis, and the magnitude of elevation influences the pretest probability for a cancer-related etiology. Severe hypercalcemia, defined as >14 mg/dL, raises concern for malignancy. PTH remains a critical first step in refining the differential as most causes of cancer-related hypercalcemia demonstrate a suppressed PTH. Severe hypercalcemia and a PTH > 5 times the upper limit of normal can raise concern for parathyroid carcinoma; however, this diagnosis accounts for < 1% of primary hyperparathyroid cases. Ectopic PTH-producing tumors are rare and most commonly occur in the lung. Primary hyperparathyroidism is usually caused by a single benign parathyroid adenoma (80-85% of cases) and is less commonly due to multiglandular parathyroid hyperplasia. Despite an uncommon presentation, our patient was ultimately diagnosed and treated for parathyroid adenoma. The combination of severe symptoms, extreme elevation in calcium and PTH, and suspicious lung nodules raised appropriate concern for malignancy. While these cancers are rare, they must be considered to avoid unnecessary parathyroid surgery and incorrect treatment. Due to increased use of routine labs, most cases of primary hyperparathyroidism are asymptomatic at diagnosis, allowing the general internist to intervene long before hypercalcemic crisis. This case underscores the clinical adage ‘common things are common,’ while illustrating the value of deliberate and nuanced clinical reasoning in uncovering atypical presentations.
Specialty/Research Institute
Graduate Medical Education
Specialty/Research Institute
Internal Medicine
