What is the Origin of Thyroid C-Cells?

The designation "C-cells" stands for Calcitonin cells, reflecting their main secretory product. They are also termed parafollicular because of their location adjacent to the thyroid follicles. Their embryonic origin is distinct from the follicular cells, arising from the neural crest, which contributes to their neuroendocrine characteristics.

What is the Mechanism of Thyroid C-Cells?

The primary stimulus for calcitonin release from the C-cells is an elevation in the concentration of ionized calcium in the peripheral blood. The C-cells possess calcium-sensing receptors (CaSRs) on their surface. When serum calcium levels rise, CaSR activation triggers a signaling cascade that culminates in the exocytosis of calcitonin-containing vesicles. Circulating calcitonin then travels to the bone, where it binds to receptors on osteoclasts, transiently inhibiting their bone-resorbing activity and contributing to the acute lowering of serum calcium.

Thyroid C-Cells

Meaning

Thyroid C-cells, also known as parafollicular cells, are a distinct population of neuroendocrine cells located within the thyroid gland, interspersed among the follicular cells but not part of the follicles themselves. Their primary physiological function is the synthesis and secretion of the peptide hormone calcitonin. Calcitonin plays a role in calcium homeostasis, primarily by inhibiting bone resorption by osteoclasts. These cells are clinically significant because they are the origin of medullary thyroid carcinoma, a relatively rare form of thyroid cancer.

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How Do GLP-1 Agonists Affect Thyroid Cancer Risk?

GLP-1 agonists carry a theoretical risk for a rare thyroid cancer based on animal data, but large human trials have not confirmed this risk.

∞ GLP-1 Agonists
∞ Thyroid C-Cells
∞ Receptor Agonists

HRTioAugust 3, 2025

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How Do Semaglutide Protocols Influence Thyroid Health Long Term?

Semaglutide primarily influences thyroid health indirectly by improving metabolic markers through weight loss, with direct C-cell effects being a species-specific concern not established in humans.

∞ Thyroid Function
∞ Thyroid Health
∞ Semaglutide

HRTioAugust 1, 2025