Read the whole article, or scroll down to the question "Is there a connection between thyroid health and MTHFR?"
I like what he says about TSH - "TSH measurement by itself is worthless. It is similar to someone asking you where the car keys are and you reply back, "Over there." ‘Where?’ you ask again. They reply back, "Over there." Not very helpful unless the person actually points where ‘there’ is or defines it better for you."