Thyroid
The thyroid was a gland found in the endocrine system of many species, which regulated hormones in the body. Among the systems affected by the thyroid gland were those regulating body size.

In Takarans, the thyroid gland was located in the lateral sternal. ()

In 2267, to snap Spock out of his Omicron spore-induced spell, James T. Kirk taunted him by calling him, among other things, "an elf with a hyperactive thyroid" ()

In 2371, Doctor Julian Bashir found no thyroid problems while examining a Jem'Hadar baby Quark had unknowingly taken possession of. ()

In 3188, Cleveland Booker told Michael Burnham that Grudge had a thyroid condition. ()

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Glands