Endocrine Abstracts

Objective: LT4/LT3 combination treatment for persistent hypothyroid symptoms is increasingly used and requested by patients, but the efficacy and side effects of long-term therapy remain largely unexplored. This study aimed to describe the patient group experiencing a long-lasting effect of LT4/LT3 and to evaluate the impact on Quality of life (QoL) and hypothyroid symptoms.

Method: In this cross-sectional study, we invited 147 patients. We included 66 patients (64 female) who initiated LT4/LT3 combination treatment between 2010 and 2018. ThyPRO39 was used to evaluate QoL, and a validated symptom score was used to assess symptoms. The patients were classified as responders (patients with long-lasting effects of LT4/LT3 therapy) versus non-responders (patients without any improvement related to combination therapy). QoL data and symptom scores were compared to historical data from the general population and data from patients with persistent symptoms (QoL) before initiating combination therapy and untreated hypothyroid patients (symptom scores).

Results: The participants (54 responders and 12 non-responders) were a median of 56 years and had had LT3 for 4.2 years. Comorbidity was seen in 74% of patients; 17% had experienced depression, and 46% had had a period of stress. QoL in the responder group was similar to historical data from the general population. However, surprisingly, symptom scores were high and at the same levels as symptom scores seen in untreated hypothyroid females (<60 years). T3 dose was increased during the follow-up period in 24% of responders, and 38% had s-TSH below the reference range (<0.4mU/l). When comparing QoL in the responders TSH<0.4mU/l versus TSH>4.0, a tendency of better scores were seen in the “Anxiety” score (10 vs 18, P = 0.01), “Emotional susceptibility” score ( 13 vs 21, P = 0.02) and ThyPRO composite score (17 vs 23, P = 0.04,) in the patients having TSH<0.4, however not significant when adjusting for multiple testing. When comparing Symptom scores, low TSH was associated with lower scores regarding “Mood lability”(14% vs 55% having normal TSH, P = 0.003). Two patients had known osteoporosis, and one was diagnosed with atrial fibrillation (all in the responder group). Complaints of other side effects were absent.

Conclusion.: Evaluated on QoL, the patients in the responder group experience QoL comparable to the background population after 4 years of treatment, with few side effects. Surprisingly, despite good QoL they still report as many hypothyroid symptoms as younger women with untreated overt hypothyroidism.