It hap­pens often – someone will join a patient group, and right off the bat, you notice they are very defen­sive about cer­tain sub­jects,  know-it-all argu­men­ta­tive, con­des­cen­dingly over­bea­ring, and/or paranoid.
They may quickly fly off the handle.  They might see impli­ca­tions in words that were never there. They can also be chil­dish in their reac­tions, obses­sive about cer­tain topics or peo­ple, mis­trust­ful of others, for­get­ful, com­ba­tive, and/or jittery.
Even worse, com­bine someone with inte­lli­gence and a way with words along with all of the above, and you’ve got a royal pain in the butt.
And the worst part?  Most have no idea how badly they are mani­fes­ting the above.
http://www.stopthethyroidmadness.com/2010/06/08/defensive-paranoid-frequently-anxietal/