An infant with persistent pulmonary hypertension of the newborn and congenital hypothyroidism.

Objectives: We report an infant who presented with persistent pulmonary hypertension of the newborn (PPHN) to highlight this was likely due to congenital hypothyroidism. Case presentation: A male infant born at term presented with respiratory distress and hypoxia two hours after birth requiring intubation and ventilation. Due to worsening clinical condition he was transferred from the local neonatal unit to a tertiary neonatal intensive care unit (NICU) for further management. An echocardiogram showed a structurally normal heart but with reduced right ventricular function and suprasystemic pulmonary artery pressures of 80 mmHg. There he required additionally inhaled nitric oxide, hydrocortisone, and intravenous fluid boluses. Sepsis was suspected as the underlying cause for the PPHN, but the infection screen was negative. He was subsequently diagnosed with congenital hypothyroidism on the newborn blood spot screening test. A technetium thyroid scan showed reduced uptake in the thyroid gland, in keeping with thyroid dyshormonogenesis. After consultation with the paediatric endocrinologists, he was commenced on levothyroxine and has made a good recovery. Conclusions: PPHN and congenital hypothyroidism have rarely been reported in association with each other. Yet, thyroid hormones play a crucial role in perinatal cardiovascular adaptation, through their effects on vascular resistance, cardiac contractility and response to circulating catecholamines. This case emphasises that it is important to fully investigate an infant with apparently unexplained PPHN for rarer causes.