A recent ct scan after a snowboarding accident mentions that i have "13mm left inferior thyroid nodule is hypodense". what does this mean?

More workup...: Opinions vary, but... Especially for women, thyroid nodules are very common. These are sometimes familial or inherited. There is likely little to be worried about, but biopsy of nodules 8 or 10mm or larger is recommended. Definitely get checked out (ent, endocrinologist, etc.) with blood tests, ultrasound, and fna biopsy, but don't lose too much sleep over it!

Possibly colloid : Most commonly this is a benign thyroid nodule, such as a cyst or colloid nodule. Thyroid us may give better specificity but you should also consult your dr. / endocrinologist since all imaging needs to be placed in the proper patient context.

Probably benign: Most thyroid nodules are benign. You should have a thyroid ultrasound to further evaluate. If needed, ultrasound guided biopsy can also be performed.

Needs ultrasound : Likley nothing to worry (lot of people have nodules); need ultrasound thyroid to confirm.