DS, 4.5 on a testosterone surge??

[supadoula]

DS has always been rather easy-going and laid-back. He has a sister 2 years older and gets on well with her. They play well and interact a lot.
For the last few days though, he has just been very angry, shouting a lot, throwing things and physically very rough.
It is very challenging and rather unexpected. I just wanted to know if anybody is in the same situation and what they do about it!

I have actually read that they have a testosterone surge around 4. (I think it was in Raising Boys by Steve Biddulph).
My boys were both horrible at 4. No trouble with terrible twos but oh did they make up for it at four.
It's just a stage, like all the rest and you will see your lovely little boy back soon. Until the next stage.