Some neonates born to mothers with Graves's disease will develop overt thyrotoxicosis while others will not. Tamaki et al developed a binding-stimulation index to help identify neonates with overt thyrotoxicosis requiring therapy. The authors are from Osaka University in Japan.



(1) TSH binding inhibitor immunoglobulin (TBII), expressed in U/mL

(2) thyroid stimulating antibody (TSAb) expressed in TSH microunit equivalents (TSH µUEq)



(1) TSH binding inhibitor immunoglobulin: radioreceptor assay from Travenol Co, with normal reference range < 0.5 U/mL

(2) thyroid stimulating antibody: increase in cycle AMP in FRL-5 cells compared to TSH, with normal reference range < 0.35 TSH µUEq


binding stimulation index =

= (TBII) * (TSAb)



• minimum score: 0

• maximum score: > 200

• A score > 15 predicts neonatal overt thyrotoxicosis, even if the mother was treated with antithyroid medications.


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