In primary hyperparathyroidism, the majority of cases are due to which finding?

In primary hyperparathyroidism, the majority of cases are due to which finding?

• A. Parathyroid hyperplasia
• B. Carcinoma
• C. Single adenoma
• D. Adenoma in all four glands

Answer: (C)

The main idea here is that primary hyperparathyroidism is most often caused by a single parathyroid adenoma. A solitary adenoma in one gland produces excess PTH autonomously, driving elevated calcium levels, while the other glands are typically normal or suppressed. This pattern accounts for the largest share of cases—about eighty-something percent. The remaining cases usually involve multigland disease, such as hyperplasia affecting multiple glands, or rarely parathyroid carcinoma. The notion of an adenoma in all four glands is not the typical presentation and doesn’t fit the common pattern, which is why a single adenoma best explains the majority of primary hyperparathyroidism.

The main idea here is that primary hyperparathyroidism is most often caused by a single parathyroid adenoma. A solitary adenoma in one gland produces excess PTH autonomously, driving elevated calcium levels, while the other glands are typically normal or suppressed. This pattern accounts for the largest share of cases—about eighty-something percent. The remaining cases usually involve multigland disease, such as hyperplasia affecting multiple glands, or rarely parathyroid carcinoma. The notion of an adenoma in all four glands is not the typical presentation and doesn’t fit the common pattern, which is why a single adenoma best explains the majority of primary hyperparathyroidism.