anyway, you should take it seriously. Listen to him, try to understand HIM, HIS mind, HIS heart, HIS thinking,weakness...all HIS HIS HIS.....NOT NOT NOT YOURS. Talk with him and let him just speak out what he wants to say and what he want you to do...
Thinking death( to end his own life ) is typical symptoms for depression.
Find more information about anxety and depression from books or internet. If you love your son you should never take it for granted that he should not have such kind of infirmites...
you may not know or not want to know anything about these but you should and you have to before it becomes to late,