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Table 1 Clinical features and diagnostic tests for RTHβ and RTHα

From: A clinician’s guide to understanding resistance to thyroid hormone due to receptor mutations in the TRα and TRβ isoforms

Typical Clinical Features
-Goiter -Bradycardia
-Resting tachycardia -Neurodevelopmental delay
-Osteoporosis -Anaemia
-Short stature -Skeletal dysplasia
-Attention deficit disorder -Dysmorphia
-Family history (80%) -Constipation
Diagnostic Tests
-Increased fT3, fT4(Rule out antibody interference) -Decreased T4/T3 ratio
-Normal/Elevated TSH -Normal TSH
-Normal dialyzed free T4 -Exon sequencing of TRα
-Rule out autoimmune thyroiditis (anti-thyroid peroxidase, thyroglobulin, and TSH receptor antibodies)  
-Check serum markers TH hyperfunction (increased SHBG, ferritin, pro-collagen-1-N-terminal peptide (PINP) and decreased cholesterol in hyperthyroidism but normal in RTH)
-Check serum a-GSU and compare with TSH (α-GSU (μg/l)/TSH (mU/l)] × 10 > 1.0 (suggests TSHoma)
-Consider pituitary MRI (rule out TSHoma)
-Exon sequencing of TRβ