Abstract 1771

It has been reported in literature that congenital hypothyroidism presents diverse clinical manifestations in the neonatal period. We report here the case of a male infant born with normal growth parameters, at term, and after uneventful pregnancy and delivery. He was discharged after two days, but at five days of life, the patient was re-hospitalized for cyanosis, somnolence and decreased feedings. On arrival, jaundice and an oxygen (O2) saturation of 87-89% without respiratory distress were noted and O2 saturation was corrected with a low supplement of O2. The decrease in O2 saturation was present mostly during sleep and less associated with feedings. The initial investigation showed no sign of infection, cardiopathy or respiratory obstruction. There were some irregularities on the EEG without definite epileptic activity, but signs of CO2 retention were present on the arterial blood analysis. On the first oxymetric study, the average O2 saturation was 91% with frequent episodes of desaturation down to 81%. The neonatal screening revealed the presence of a high TSH and low free T4 suggesting congenital hypothyroidism. A thyroid technitium scan indicated the presence of an ectopic lingual thyroid gland so L-thyroxine was started at a dose of 10 µg/kg/day. There was an initial decrease of the number of episodes of desaturation, then stagnation. However, a repeat of the oxymetric study demonstrated improvement with an increase of the average O2 saturation to 93% and shorter, fewer desaturations. The neurological investigation was completed with a head CT scan and IRM which were both normal. The EEG-video monitoring still exhibited some irregularities: a short trial of 8 days of phenobarbital was started but induced no improvement. A decrease in the TSH with higher dosages of L-thyroxine was associated with a higher average O2 saturation at 94% in room air. After one month of treatment, the oxymetric study was normal with no significant episode of desaturation and the patient was discharged. During a visit, two weeks later, the patient was above the 90th percentile for all his growth parameters and showed no residual symptoms. In conclusion, the improvement of the hypoventilation paralleled by a decrease of TSH and increase of T4, suggests that central alveolar hypoventilation is a plausible, albeit uncommon, manifestation of congenital hypothyroidism.