The effect of Vitamin B12 deficiency on the GH-IGF1 axis

Abstract

Vitamin B12 (B12) deficiency is associated with growth retardation, reduced serum osteocalcin levels, lower bone mineral density, and increased bone fracture risk, yet the underlying mechanisms remain unclear. However, a recent study showed that B12 positively regulates postweaning growth and bone formation via taurine. B12 deficiency causes growth hormone resistance (GH) and IGF1 (Insulin-like growth factor-1) deficiency. In the present study, we aimed to evaluate the effect of B12 deficiency on the axis of GH-IGF1 and serum taurine level. Eighteen children with B12 deficiency (B12 düzeyi <180 pg/ml) who were 2-17 years-old and referred to Pediatric Haematology Unit in Diyarbakir, between June-August 2015, were included. These subjects had also no growth retardation or any chronic disease. Serum growth hormone, IGF1, IGFBP3 (IGF binding protein-3) and taurine levels were measured before and after oral B12 treatment during 1 month (<20 kg 500 mcg/day, >20 kg 1000 mcg/day). The mean age of the 18 subjects (6F/12M) was 8.0±4.8 years-old. The levels of serum B12, growth hormone, IGF1, IGFBP3 and taurine before and after oral B12 treatment were 132.6±28.4 pg/ml vs 655.8±384.4 pg/ml, 1.20±1.98 vs 1.35±1.20 ng/ml, 213.9±185.8 vs 217.8±181.5 ng/ml, 3683.5±1497 vs 3583.5±1207.3ng/ml, 32.7±18.0 vs 41.1±30.4 μmol/L (N:10-170) (p<0.0001,p=0.41,0.37,0.28 ve 0.31, respectively). The present study did not detect any relation between B12 deficiency and the GH-IGF1 axis. However, there is a need for the studies that are performed in children with more severe and long-term B12 deficiency.