AANP Family Nurse Practitioner (FNP) Certification Practice Exam

The primary hormone released by the parathyroid gland that regulates calcium levels in the body is parathyroid hormone (PTH). This hormone plays a crucial role in maintaining calcium homeostasis by increasing calcium levels in the blood when they fall below normal. PTH achieves this through several mechanisms: it stimulates the bones to release calcium, enhances the kidneys' ability to reabsorb calcium, and promotes the activation of vitamin D, which in turn increases intestinal absorption of calcium. Understanding the role of PTH is essential, especially in conditions like hypoparathyroidism, where low levels of PTH lead to hypocalcemia, or in hyperparathyroidism, where excessive PTH results in hypercalcemia. This regulation of calcium is vital for numerous bodily functions, including nerve conduction, muscle contraction, and blood coagulation. Other hormones listed do not primarily originate from the parathyroid gland nor serve the primary function of regulating blood calcium levels. For instance, calcitonin is produced by the thyroid gland and works in opposition to PTH by lowering blood calcium levels, while thyroxine is primarily involved in metabolism, and cortisol plays a role in the stress response and metabolism but does not directly regulate calcium.