C62-14 Unmasking Rickets in a Tachypneic Toddler

Introduction While uncommon in the United States, rickets remains a significant cause of global morbidity. The importance of adequate vitamin D for lung health is becoming increasingly recognized, particularly in preventing acute respiratory infections and optimizing immune function. This case describes a patient presenting with tachypnea and bronchomalacia who was found to have severe vitamin D deficiency. Description of Case A 15-month-old female presented to clinic for failure to thrive and tachypnea with intermittent dyspnea. Her exam was notable for subcostal and suprasternal retractions, expiratory grunting, normal oxygen saturations, and an increased respiratory rate of 55 breaths per minute. Breath sounds clear were bilaterally. She had gross motor delay and was unable to crawl or independently stand. Her weight gain has been poor since 4 months of age, currently 7.1kg (z-score= -3.71). She was exclusively breast-fed until the introduction of solid foods at 6 months of age; parents deny any concern for aspiration. She recently had a viral upper respiratory infection but has otherwise been healthy. Her birth history is significant for 36-week prematurity, no respiratory concerns or oxygen requirement. Given her failure to thrive and unclear etiology of tachypnea, she was admitted to the hospital for further evaluation. Her chest x-ray showed foreshortened ribs with flaring of the anterior rib ends with a bell-like shaped chest wall (Figure 1). A dynamic airway computed tomography was notable for bilateral peripheral mainstem bronchomalacia, multifocal air trapping involving both lungs (Figure 2). Overnight saturation study without hypoxia and blood gas monitoring was without evidence of hypoventilation. While awaiting more invasive evaluation including bronchoscopy and endoscopy, nutritional evaluation revealed severe vitamin D deficiency, elevated alkaline phosphatase and PTH, consistent with a diagnosis of rickets. Discussion This case highlights a unique presentation of a toddler with tachypnea and bronchomalacia found to have rickets. The differential diagnoses for why this this patient had both tachypnea and poor weight gain were broad and included interstitial lung disease, congenital pulmonary malformation, sleep disordered breathing, neuromuscular disorders, skeletal dysplasia, severe laryngomalacia, and gastrointestinal losses. Vitamin D deficiency should be considered as a potential contributing factor to airway malacia and failure to thrive, especially in children with a history of being exclusively breast-fed. The prevalence of lower airway malacia in patients with rickets may be underreported and should be further investigated.