What is the primary cause of primary hyperparathyroidism?

The primary cause of primary hyperparathyroidism is an adenoma of the parathyroid gland. This is a benign tumor that leads to excessive production of parathyroid hormone (PTH), which in turn increases calcium levels in the blood by promoting calcium release from bones, increasing calcium absorption in the intestines, and encouraging reabsorption of calcium in the kidneys. The condition is primarily characterized by hypercalcemia, elevated PTH levels, and often presents with symptoms related to high calcium levels, such as fatigue, weakness, and kidney stones.

In contrast, while chronic kidney disease can lead to secondary hyperparathyroidism due to imbalances in calcium and phosphorus levels, it is not the cause of primary hyperparathyroidism. Genetic predisposition can play a role in some individuals developing parathyroid tumors, particularly in conditions like Multiple Endocrine Neoplasia (MEN) syndromes, but it is not the most common cause overall. Vitamin D deficiency primarily affects calcium metabolism but does not cause primary hyperparathyroidism; instead, it can lead to secondary hyperparathyroidism as the body attempts to compensate for low calcium levels resulting from inadequate vitamin D. Hence, the presence of an adenoma is the most direct and prevalent cause of