Could somebody please help me get to the bottom of what is wrong with me? I have had raised MCV on my FBC for several years now (5-6+), my MCH has been in range for the last couple of years, but had also been raised for a couple of years previously. Last January I was told by my GP I had folate deficiency my result was 4.4 I supplemented with folic acid for a month and when retested a couple of months later it was at 26.0, problem solved, however my MCV is still continually raised. I have neuropathy of my hands feet and tongue, burning sensations/pins and needles, I have had problems swallowing bulky foods on and off for the past 18 months, fingernails are falling to bits and have faint white lines near the top, mild hair loss. I have had IBS since my 20,s I am now 47, however I have had chronic diarrhoea for the past 2 years. I am now suffering from fecal urgency, no warning and urinary stress incontinence/urgency. I was diagnosed with psoriatic arthritis 7 years ago, auto immune in nature. I have had my thyroid tested several times, also for diabetes and tested for coeliac disease, all negative. My B12 was at 284 at the same time as my folate deficiency, this further dropped to 247 a few months later. I take omeprazole as I am on celecoxib anti inflammatory for the PSA along with steroids, sulfasalazine, leflunomide etc I have been on most of these medications for 7 years bar the leflunomide which I restarted last summer after a 10 month break. My GP put me on some B12 tablets in November for a month then retested, my level had gone up to 295, I requested some more as I thought my level was still quite low and he obliged. I have just been retested and my B12 level is now 411, folate 13 with no supplements since the beginning of last year, but my symptoms are not improving and my MCV is on the rise again. I have been to see the dental team at Guys regarding the burning tongue and she is in agreement that it is a neuropathy, she has advised for neurological testing (nerve conduction test) she also did an iron panel test as my ferritin has been low for quite a while (In the 30’s) but has dropped in the last 9 months to 16, however my iron level results came back within range???? She also tested zinc and this was borderline low. Any ideas? Anyone?? Can I just add that all my liver results have been fine and urea and electrolyte all come back normal, although my potassium does keep dropping, but still within range.