Hi,
If TSH is elevated (> 10 miu/l ) with normal T4 in an asymptomatic patient, we consider severe subclinical hypothyroidism as probable diagnosis.
In your case I would recommend you to retest TSH along with Anti TPO antibodies. If TSH > 10 in second report, treatment with levothyroxine supplementation is advised. If TPO is positive along with positive family history, chances of permanent hypothyroidism are high.
Severe subclinical hypothyroidism if left untreated, can progress to overt hypothyroidism along with increase in heart attacks, heart failure, infertility, fatty liver and all cause mortality.