We hypothesize that critically ill children that require vasoactive infusions and/or invasive mechanical ventilation have thyroid hormone alterations. We will measure TSH, tT3, fT3, rT3, tT4, fT4, adn tyrosine concentrations in critically ill children with hypotension and/or respiratory failure and correlate thyroid hormone alterations to severity of illness, intensity of therapeutic interventions, and associated morbidity and mortality by using clinical outcomes parameters.
