Clinical management of short children with low serum immunoglobulin but no immunodeficiency features

Background: In children of different ages investigated for failure to thrive, low (below the cut-off for age) immunoglobulin (Ig) values can be detected, without any clinical evidence of humoral immunodeficiencies. To better characterize infants presenting with diminished immunoglobulin levels, we studied IgG subclasses, in vitro Ig production and B cell subpopulation. Methods: We monitored 17 children (12 boys and five girls, age range 1-18 years) with low serum levels of one or more Ig isotypes but without any clinical or laboratory features of immunodeficiency. Results: Low IgM levels were frequent (52.9%). During the follow up, six of 17 cases (35.3%) normalized their immunoglobulin levels. Frequently, in the observed patients, low levels of immunoglobulins were not limited to the period of infancy. In all patients, in vitro Ig production and B lymphocyte subpopulations were within normal ranges. Conclusions: We suggest a quantification of serum Ig levels in children who fail to thrive in order to identify patients with low Ig levels. These children should be monitored until Ig levels normalize to exclude any immunodeficiency status. Early recognition of children with persistent hypogammaglobulinemia would allow prompt and appropriate clinical interventions.