gigantism

noun

1. (countable, uncountable)The quality or state of being gigantic; being of abnormally large size.
2. (countable, uncountable)A condition where there is over-production of growth hormone by the pituitary gland in a child before the bone growth plates close, resulting in excessive long bone growth, accompanied by muscular weakness and sexual impotence.

   “He [...] may have had a condition called gigantism that explained his notable height.”