Thyroid parafollicular (C) cells
Sensor / first step · Neural crest CaSR
C cells lie between the thyroid follicles, arise from neural crest by way of the ultimobranchial body, and carry the same calcium-sensing receptor. A rise in ionised calcium makes them secrete calcitonin.
Traced from the start
- Rise in ionised calcium
- Thyroid parafollicular (C) cells
Detail
- Origin
- Neural crest cells migrating through the ultimobranchial body of the fourth pharyngeal pouch, scattered in the interfollicular thyroid
- Stimulus
- High ionised calcium acting on the calcium-sensing receptor; also gastrin, the basis of the historical pentagastrin provocation test
- Products
- Calcitonin, and procalcitonin, the marker used in sepsis
When it goes wrong
Medullary thyroid carcinoma, sporadic or with a RET mutation in MEN 2A or MEN 2B
Calcitonin and CEA are the tumour markers; exclude phaeochromocytoma before neck surgery, and note that serum calcium is characteristically normal
Total thyroidectomy with the parathyroids preserved
No disturbance of calcium at all, which is the clearest evidence that calcitonin is not required for calcium homeostasis in adults
Practise this structure
4 questions in the bank tagged Thyroid.
A 42-year-old man was treated with radioactive iodine for Graves disease three days ago. He now reports dry mouth and painful swelling in front of both ears, wo…
Clinical rotations · common
A 34-year-old woman taking carbimazole for Graves disease presents with fever, malaise and two painful oral ulcers. She has a temperature of 38.7°C and mild cer…
Clinical rotations · common
A 35-year-old woman has palpitations and a 9 kg weight loss over 3 months. Her free thyroxine is 48 pmol/L (reference 10–22 pmol/L), TSH is less than 0.01 mIU/L…
Mechanisms of disease · common
A 38-year-old woman presents with two weeks of pain in the front of her neck radiating to her jaw, together with palpitations, sweating and 2 kg of weight loss.…
Clinical rotations · common