Thymus size in children with moderate malnutrition: a cohort study from Burkina Faso

Background Moderate acute malnutrition (MAM) affects millions of children, increasing their risk of dying from infections. Thymus atrophy may be a marker of malnutrition-associated immunodeficiency, but factors associated with thymus size in children with MAM are unknown, as is the effect of nutritional interventions on thymus size. Methods Thymus size was measured by ultrasound in 279 children in Burkina Faso with MAM, diagnosed by low mid-upper arm circumference (MUAC) and/or low weight-for-length z -score (WLZ), who received 12 weeks treatment with different food supplements as part of a randomized trial. Correlates of thymus size and of changes in thymus size after treatment, and after another 12 weeks of follow-up were identified. Results Thymus size correlated positively with age, anthropometry and blood haemoglobin, and was smaller in children with malaria. Children with malnutrition diagnosed using MUAC had a smaller thymus than children diagnosed based on WLZ. Thymus size increased during and after treatment, similarly across the different food supplement groups. Conclusions In children with MAM, the thymus is smaller in children with anaemia or malaria, and grows with recovery. Assuming that thymus size reflects vulnerability, low MUAC seems to identify more vulnerable children than low WLZ in children with MAM. Impact Thymus atrophy is known to be a marker of the immunodeficiency associated with malnutrition in children. In children with moderate malnutrition, we found the thymus to be smaller in children with anaemia or malaria. Assuming that thymus size reflects vulnerability, low MUAC seems to identify more vulnerable children than low weight for length. Thymus atrophy appears reversible with recovery from malnutrition, with similar growth seen in children randomized to treatment with different nutritional supplements.