IMPE Abstracts

Introduction: Thyroid Hormone Resistance (THR) is an uncommon genetic condition caused by decreased tissue sensitivity to thyroid hormones (THs). The main finding is the presence of elevated THs levels with unsuppressed TSH. In THR clinical signs of hormonal deficiency, sufficiency and excess can coexist.

Aim: To report the clinical and biochemical findings in patients withTHR, highlighting common characteristics that could guide their management.

Methods: Retrospective review of clinical records of patients with biochemical findings of suspected THR. All patients underwent a TRH stimulation test to rule out the presence of thyrotropinoma and a molecular testing to confirm diagnosis.

Results: Seven patients were included, 3 girls and 4 boys. Variants in the THRB gene were found in 5 cases: 4 in exon 10 and 1 in exon 9. Median age at first visit was 9.7 +/- 5.02 years. The most frequent reason for consultation (4/7) was an abnormal thyroid function test. A single case consulted for tachycardia. Three patients reported hiperactivity disorders, 4 learning disorders, 4 sleep disorders, and 2 constipation. Goiter was found in 5 patients and tachycardia in 3. Initial height was normal in most patients (mean SDS height 0.7 +/- 1.03), except for one patient who presented tall stature and karyotype 47XXX. BMI SDS -0,09 +/- 2,15, two patients presented obesity and one was underweight. Mean TSH was 4.13 +/- 1.69 mUI/l, mean FT4 was 2.16 +/- 0.62 ng/dl and mean TT3 was 234 +/- 97 pg/dl. Only one patient presented had positive AbTPO. TRH stimulation test was normal in all patients. We did not find association between TSH levels >5 mUI/ml and goiter size (P=0,07), nor between FT4 levels > 2 ng/dl and tachycardia (P=1). Two patients were misdiagnosed as hyperthyroidism or hypothyroidism and treated with methimazole and levothyroxine respectively, both for short periods of time. Due to difficult management of hyperthyroidism, a patient received methimazole and beta blockers for a short time, finally she was medicated with triiodoacetic acid therapy.

Conclusions: Abnormal thyroid function tests were the most common reason for referral (57%), but hyperthyroidism symptoms were found in most patients in a thorough anamnesis. Goiter was the most frequent clinical finding and half of the patients had tachycardia. Presence of discordant thyroid profile should raise suspicion of this condition, guiding the diagnosis and avoiding unnecessary treatments.