The PTH test evaluates parathyroid gland function and calcium metabolism. Elevated PTH levels are often associated with hyperparathyroidism, presenting symptoms like bone pain, kidney stones, and fatigue. Low PTH levels can indicate hypoparathyroidism, causing symptoms such as muscle cramps, tingling, and convulsions. This test is essential for diagnosing parathyroid disorders, assessing calcium and phosphate imbalances, and guiding treatment decisions.