Replied by Timh (Louisville, Ky, Usa) on 06/30/2012
Loren, I have supplemented L-Carnitine for yrs and have only recently began having Hypothyroid problems myself, although I have never heard of a connection between the two. Generally speaking, most all nutritional supplements, taken in moderate amounts, augment (nourish) body functions, not suppress them. Carnitine's primary function is to help the body burn fat for energy, and doesn't have any direct relation to the thyroid gland.
Recently my thyroid is better even though I only took "Armor" a few times rather than every day (because it upset my stomach); but I have lately been taking 2 soft-gels of Virgin Coconut Oil (which is very good for thyroid).