Primary hyperparathyroidism is characterized by excessive production of PTH and hypercalcemia. In 80 percent of cases, it is caused by a benign solitary parathyroid adenoma. Surgical reports suggest multiple adenomas are present in 2 to 4 percent of cases. About 15 percent of patients have diffuse hyperplasia of all four parathyroid glands, a condition that is frequently hereditary. Secondary hyperparathyroidism occurs as a result of low serum calcium levels.
Most cases have hyperplasia in all four parathyroid glands.
Calcium oxalate or phosphate stones may develop. Polydipsia and polyuria are often reported and are secondary to hypercalcemia. Eventually, renal failure and nephrocalcinosis may result. Although mild hypercalcemia is often asymptomatic, more severe cases can cause nausea, vomiting, thirst, and anorexia. A history of peptic ulcer disease or hypertension is not uncommon, and there may be accompanying constipation, anemia, and weight loss.