Poor Growth, Thyroid Dysfunction and Vitamin D Deficiency Remain Prevalent Despite Reduced Intensity Chemotherapy for Hematopoietic Stem Cell Transplantation in Children and Young Adults

Myeloablative conditioning regimens for hematopoietic stem cell transplant (HSCT) are known to affect endocrine function, but little is known regarding reduced intensity conditioning (RIC) regimens. We retrospectively reviewed 114 children and young adults after single RIC HSCT. Analysis was grouped by age (<2y and ≥2y), and diagnosis (HLH/XLP, other immune disorders, metabolic/genetic disorders). All groups displayed short stature by mean height adjusted Z-score (HAZ) before −1.29 and after HSCT (HAZ −1.38, p=0.47). After HSCT, younger children with HLH/XLP grew better (HAZ −3.41 vs −1.65, p= 0.006), while older subjects had worsening (HAZ −0.8 vs −1.01, p= 0.06). Those with steroid therapy beyond standard GVHD prophylaxis were shorter than those without (p 0.04). After HSCT, older subjects with HLH/XLP became thinner with mean BMI Z-score of 1.20 vs. 0.64, p=0.02, likewise in metabolic/genetic disorders (BMI-Z= 0.59 vs. −0.99, p<0.001). BMI increased among younger children in these same groups. Thyroid function was abnormal in 24% (18/76). 25-OH vitamin D levels, were insufficient in 73% (49/65), with low bone mineral density in 8 of 19 evaluable subjects. Despite RIC, children and young adults still have significant late endocrine effects. Further research is required to compare post-transplant endocrine effects after RIC to standard chemotherapy protocols.