Parathyroid carcinomas are usually bigger and more metabolically active than adenomas, in a way that most cases are associated with extremely elevated serum calcium and PTH levels (total calcium levels higher than 3.0‐3.5 mmol/L5, 21 and PTH levels at least 10 times higher than normal).21, 25. This evidence concerns the gene PTH and parathyroid gland carcinoma.