Wife of 54 has a low TSH of 0.01 and high FT4 of 19.5 -diagnosis is Hyperthyroidism. Could it be a Pituitary problem - no weightloss or other symptoms?
In brief: Pituitary unlikely
You may visit this site for information on this topic. https://www.mayoclinic.org/diseases-conditions/graves-disease/symptoms-causes/syc-20356240
Wish both of you good health!