Which hormone lowers blood calcium levels?

Calcitonin is the hormone known for its role in lowering blood calcium levels. It is produced by the parafollicular cells (also known as C cells) of the thyroid gland. The primary action of calcitonin is to inhibit osteoclast activity in the bones, which reduces the release of calcium from bones into the bloodstream. Additionally, calcitonin promotes the excretion of calcium by the kidneys, further contributing to lower blood calcium levels.

Understanding the context of calcitonin's action helps clarify its importance in calcium homeostasis. It works in tandem with parathyroid hormone, which has the opposite effect by increasing blood calcium levels. This balance between calcitonin and parathyroid hormone is crucial for maintaining stable calcium levels in the body, supporting various physiological functions including bone health, muscle contraction, and nerve transmission.