I had a hemi thyroidectomy in 2006 right side i recently had a ct of my neck for other reasons and the results came back with a heterogenous enlargement of myl left side. should i be concerned?

Thyroid enlargement: Heterogeneous means uniform enlargement of the thyroid. Usually we are more concerned when there is a specific nodule rather than increase in the entire lobe itself. Check with your dr. Who ordered the cat scan to be sure.

Yes see your MD : If hemithyroidectomy is done for malignancy, yes you have to be concerned , need further work up possible fine needle biopsy to prove other wise. You have to see your doctor.

Need an ultrasound: If the right side was taken out and u were not placed on thyroid replacement, it's common for the left side to overcompensate & gets a little bigger. With the ct scan above, i would get an ultrasound of the thyroid to make sure there is no nodules in the "heterogenous" left lobe. If there is, u will need to follow it or get a biopsy. I assume the right was not cancerous since the left was left in.