SORTED 1: • To assess participant’s willingness to enter the trial • To gauge participant’s acceptability of study design. • To study length of time required to complete recruitment. • To assess the dose titration strategy, described above, and length of time required to achieve desired TSH levels. • To gauge medication compliance. SORTED 2: • To explore the reasons for participation in a randomised control trial (SORTED 1 Study) amongst community dwelling people aged 80 years and over with levothyroxine treated primary hypothyroidism • To explore the reasons for non-participation in a randomised control trial (SORTED 1 Study) amongst community dwelling people aged 80 years and over with levothyroxine treated primary hypothyroidism • To examine the decision-making process that elderly people make in choosing whether to participate in a randomised control trial (SORTED 1 Study) • To explore aspects of health and well-being with differing doses of levothyroxine replaceme