Endocrine Abstracts

Objectives: To evaluate the relationship between free T3 (FT3) levels with symptoms suggestive of thyroid dysfunction, and quality of life (QoL) outcomes, in patients with compensated primary hypothyroidism (PH).

Methods: Cross-sectional study encompassing Portuguese levothyroxine(LT4)-treated patients for PH who presented Thyroid-stimulating hormone (TSH) and free T4 (FT4) within the normal range. Pregnant women, patients with central hypothyroidism and/or with significant comorbidities (Charlson Comorbidity Index) were excluded. Blood samples for thyroid function tests were collected at the time of clinical evaluation. The Portuguese versions of the “Quality of Life Questionnaire for Patients with Thyroid Disease” (ThyPRO-39br) and the “MOS Short Form Health Survey 36 item v2” (SF-36v2) were applied.

Results: Two hundred and one patients were included, 176 (87.6%) were female, with a median age of 5 (minimum;maximum: 19;87) years. Chronic autoimmune thyroiditis was the most common cause of PH (n = 89[44.3%]). The median daily dose of LT4 was 100 µg (1.51µg/kg/day; minimum; maximum: 25; 250 μg). Globally, the most reported symptoms were asthenia (n = 134[66.7%]), cutaneous xerosis (n = 127[63.2%]) and muscle fatigue (n = 107[53.2%]). In the ThyPRO-39br questionnaire, 138 (68.6%) patients did not attribute a detrimental effect on their QoL to PH. Asthenia (n = 114[56.7%]), depressed mood (n = 112[55.7%]) and cutaneous xerosis (n = 94[46.8%]) were the most frequent complaints. With regard to the SF-36v2 questionnaire, most patients did not describe significant physical disability in activities of daily living. Around a third reported decreased vitality and energy, and approximately half of the patients described stability, compared to their health status in the previous year. Patients with complaints of constipation (P = 0.010) and depressed mood (P = 0.039) had significantly lower FT3 levels than patients without these symptoms. The same trend was observed in patients with asthenia, muscle fatigue, cutaneous xerosis, periorbital edema, dysphonia, weight gain, cold intolerance and memory loss, although without statistical significance.

Conclusions: Most patients with normal TSH and FT4 do not have a negative impact on their QoL, at least significantly. Despite the restoration of “euthyroidism”, there are a panoply of symptoms that remain, which may be related to a lower conversion of T4 to T3 (symptomatic patients have lower FT3 levels). The persistence of these symptoms makes us question the potential benefit of T3 therapy in this subset of patients.