peeptoad

Someone on this board (can't remember who, sorry) helped me with this last year and the advice they gave was really good (I had a negative blood test and no biopsy, so I am still not diagnosed technically).
I think this would work better for someone who has some symptoms they can use for diagnostic purposes though:

Quit ALL gluten for at least two months (this includes every last, little trace of gluten including shared equipment/cross-contamination, and this means that you likely will need to not eat out at all and prepare all food at home- it's only for 2 months).
Pay attention to the disappearance/improvement of any symptoms during the gluten-free phase. For me, personally, many of my GI symptoms were gone by the end of the second week (14 days in), and most symptoms gone by the end of the first month. Be aware that some people go through gluten withdrawal during this time, which can manifest as ataxia, vertigo, etc (this happened to me, but only lasted about 5 days).
After 2 months have gone by re-introduce gluten in a controlled manner: do not randomly start eating gluten-y junk food, or  just any old food at a restaurant, but pick a few things (like regular bread, or cream of wheat cereal) and eat the equivalent of 3-4 servings per day for at least a week. This is so you can be as accurate as possible.
Pay close attention to any symptoms that might happen during the glutening phase: these can be GI issues, skin problems, sleep problems, depression, headaches, anxiety, etc.

If a full week has gone by and there are zero symptoms, then gluten might not be the problem...

This worked great for me because when I started eating gluten again it was very clear (within 3 days) that it was a problem for me... I kept eating it and the symptoms got worse and worse until I went gluten-free again on day 7 or 8. I could see a very clear progression of symptoms during the glutening phase and they all disappeared again after I quit gluten for good.

I agree with Rosetapper. I also had a negative blood test and no biopsy done, and my GI doc said he "presumes I do not have celiac, but am just sensitive to gluten". Anyway the treatment is the same... I do go through periods where I wish I knew for sure since intolerance does not necessarily damage the villi, but celiac does and I don't want to predispose myself to cancer. (in other words I would be a little more strict with the gluten-free diet if I knew for sure).
Oh well. I'm not about the gluten myself for 2 months just to get a biopsy done that may or may not be conclusive...

How common is it to have a negative blood test and a positive biopsy?

My blood test was negative and my doctor (maybe with good reason) never went any further with testing and dismissed celiac. About a year or two later I found out onmy own that gluten was one of the major culprits in my GI problems, so I went gluten-free.
A year after that I had a routine visit with my doctor and she asked how my GI stuff was going and I told her it was mostly fine, except when I ate gluten. She then proceeded to tell me that she'd had multiple patients who tested negative on blood come back and tell her they found out gluten was a problem...

I wonder how many people actually go through with the biopsy even when the blood is negative??

Why haven't they tried to find out what is making you anemic? isn't it connected to the red cells and bone marrow depletion...
I'm going to see gastroenterology consultant tomorrow and my GP wants to investigate what has made me anemic, whether it's celiac or to do a biopsy, camera jobbie

No idea why my doc didn't investigate the cause for anemia. Pretty much everything I've done for my health in the last year has had nothing to do with my doctor anyway. I DXed myself with a gluten sensitivity (possible celiac since I never got the biopsy done- another story) via elimination/challenge. Going off gluten completely solved my GI problems, and in the last 2 months I've upped my iron supplements. Just got the ferritin re-checked 2 weeks ago, and it is rising slowly now.
My guess is going gluten-free is aiding in absorption, plus I may not have been taking enough to begin with. I actually told my doctor that, instead of the reverse happening....whatever.

I thought I would miss pizza, but I don't miss it nearly as much as I supposed I would.

For me I miss a big old crusty, baguette the most... used to love it with brie or camembert, or just dipped in olive oil.  

My fingernails used to peel/break and they were pretty flexible as well. I started taking biotin 5mg/day and it has helped a lot.

Well, the GI symptoms gradually returned over the past 7 days, and the past two mornings I was woken up by painful abdominal cramps. Also, oddly enough, I began to feel very depressed late last week (about 5 days into my glutening). Maybe this is a coincidence, but I see no reason to continue with the challenge. That's enough to convince me that I have some sort of issue with gluten. Back to the gluten-free sanctuary!