Now you mention hiccups it reminds me that my Dad used to get random bouts ofthem for no apparent reason. He was treated for an ulcer and told this was a symptom, but he didn't have an ulcer (he's not one to question what the Dr tells him) and since he's been on dialysis he's not had the hiccups. Perhaps we've made a discovery here??
I wish I could remember where I read it, but severe irritability is one of the symptoms of kidney problems (don't know why). Guess that explains why I've been such a bitch most of my life!!!!!
As for the change in your friends personality he is probably just having a hard time coming to terms with being diagnosed, not everyone can deal with it and we all have different ways of coping, he is probably angry at the world right now. Its not always down to 'toxins' , we do have emotions as well .