My father was diagnosed with thyroid cancer at 46. i am 27, but asked for a thyroid ultrasound as a precaution. the us revealed one 4x6x6mm solid nodule. should i be worried? does this merit biopsy?

Generally no...: In most instances, thyroid nodules / lesions that are less than 10 mm in size do not need biopsy. If your father had medullary thyroid carcinoma, then it might be possible that you have a familial syndrome. If he had a well differentiated cancer (papillary or follicular), then less likely to be heritable. Discuss the need to biopsy versus follow with serial ultrasounds with your provider.

Any solid nodule : Requires a biopsy. Let's hope and pray it's not malignant.

Biopsy it: Thyroid cancer can run in families. If you have a family history and a nodule a biopsy is warranted. Most thyroid nodules, however, are benign. Best wishes to you and your father.

Follow closely: Thyroid nodules are very common. The risk of cancer is only 5%. I would follow this nodule with another ultrasound in a year and would consider biopsy only if it grows on the subsequent ultrasound. Your current nodule is currently very small.