TNFRSF11B and vitamin D deficiency: Nearly, 52% of the patients had hypocalcemia [versus 25% or n = 12 control subjects], 93% of the patients had vitamin D deficiency/insufficiency [versus 30% or n = 12 control subjects with vitamin D insufficiency], and 31% had high levels of sRANKL and 49% had low levels of OPG.