Background Congenital hypothyroidism is increasingly being detected by means of newborn screening, with very few being diagnosed purely on clinical suspicion. Common symptoms include hypotonia, feeding difficulties, hypothermia, macroglossia, umbilical hernia and prolonged jaundice. However, this is not usually evident in the immediate newborn period because of protection from trans-placental transfer of maternal thyroid hormones.

Methods We present the case of a newborn baby with congenital hypothyroidism (CHT) presenting in the newborn period with bilateral upper limb proximal weakness (mimicking Erb's palsy), dislocated hips and neonatal jaundice.

Results A female baby was delivered by caesarean section for breech presentation at term to a primigravidous mother following an uncomplicated pregnancy. Routine newborn examination revealed bilateral weakness of forearms with absent Moro reflex, dislocatable hips, generalised hypotonia, hyporeflexia, lethargy, poor feeding and jaundice. Investigations showed markedly raised TSH levels (>100 mIU/l), low T4 levels, raised creatine kinase (771 pmol/l) and bilirubin needing phototherapy. Mother was euthyroid. Thyroxine replacement was started following diagnosis of primary CHT and thyroid radioactive scan is suggestive of dyshormonogenesis. Her symptoms resolved with treatment including normalisation of the creatine kinase.

Conclusion To the best our knowledge there is no reported case of hypothyroid myopathy presenting in the newborn. Maternal thyroid hormones play a protective role throughout pregnancy, but animal studies have shown that not all fetal tissues are protected.1 2 Euthyroid maternal status should therefore not preclude the consideration of CHT in any newborn presenting with hypotonia and other features of myopathy.