Thyroid Nodules · this is how the organ is built

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Iodine
Iodine is the raw material for thyroid hormone. Without enough iodine, not enough hormone is made, the pituitary keeps releasing thyroid-stimulating hormone (TSH) to push the gland, and the thyroid follicles are stimulated to grow for years; this is one route to goiter and nodules (Zimmermann 2009).

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The thyroid is made of tiny follicles

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An ultrasound that finds a thyroid nodule most likely is not showing a bad thing that has grown in you. It is the machine finally seeing this organ as it has always been.

Under a microscope the thyroid is not a solid piece of flesh but millions of tiny spheres packed together. Each one is a follicle, a few tenths of a millimeter across: a ring of lining cells forms the shell, and the center holds a pool of thick colloid. That colloid is a warehouse of finished hormone: follicle cells build a large protein called thyroglobulin, attach iodine to it and store it in the center; when hormone is needed, they take it back in and cut thyroid hormone out of it into the blood. The store lasts about two or three months (Zimmermann 2009). So the building unit of this organ is a sphere.

When a small patch of follicles grows a little more eagerly than its neighbors, it bulges into a lump one or two, or three to five, millimeters across, and the high-frequency ultrasound probes used at today's check-ups have reached exactly that resolution. Once the ruler is as fine as the organ's building unit, you start to see its natural grain. Found does not mean it was ever going to harm you.

Keep a different situation apart: a voice that stays hoarse, swallowing or breathing that becomes difficult, or a nodule that grows noticeably over a short time. Do not wait for the next check-up; see a doctor directly. The full list of warning signs is at the end of the chapter Should you avoid iodine?

Educational content, not medical advice — consult a clinician.

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