PTH and Hypercalcemia: Primary hyperparathyroidism (PHPT) is a condition characterized by elevated parathyroid hormone (PTH) levels and hypercalcemia due to excessive PTH secretion by one or more parathyroid glands. PHPT is often discovered due to elevated blood calcium levels on routine examination and/or symptoms of hypercalcemia such as polyuria, bone pain, muscle weakness, lethargy, constipation, and other digestive issues.