Hi,
Based on the information you had been treated for
thyroid issues with
radiation about 20 yrs ago and since then you are on
synthroid, and you are wanting to know the causes of deep cut in you tongue and wether its associated with thyroid issues or not .
Here are multiple reasons for cut on tongue
1) Eating foods that have sharp edges that may injure the tongue.
2) A traumatic
injury to the face and mouth, including the tongue.
3)Deficiency in
vitamins C and B.
4) Tongue ulcers: Tongue ulcers can also have signs of cuts on the tongue. However, this will not be the only symptom as it usually occurs along with other symptoms such as bumps in the tongue that bleed or have a burning sensation.
5) Fissured tongue: A condition in which the entire tongue has deep cuts or grooves, usually not very painful, and common in people as they age. This is believed to be a hereditary condition, which is usually harmless.
6) Allergic reactions to certain foods can also cause cuts in the mouth.
I don't think your cut in tongue is due to your radiation 20 yrs ago.
Its hard to see what you have but I think the answer you are look is some where in above causes.
Thanks
Dr. JAY PATEL.