I have CREST Syndrome. I had a frightening experience at the weekend. I was rung by a doctor at the crack of dawn on Saturday to say that the blood test results the previous day (which were done to check on my thyroid and cholesterol) had shown that my potassium levels were dangerously low and I had to get myself to the hospital. This is a new surgery and hospital for me having just moved to the area. To cut a long story short, they topped me up with potassium via a drip overnight and then some magnesium. This made me much worse but they didn't take any notice of that. In essence, all the symptoms they expected me to present on Saturday (I was feeling absolutely fine at that point) i.e. breathlessness, vomiting, cramps, diarrhoea, were produced by the topping up of potassium. I was discharged mid-evening on Sunday with dissolvable potassium tabs and a Ranatidine to replace my Omeprazole. Back home I took the first two dissolvable tabs and my usual evening pills except that I replaced the Omeprazole with the Ranatadine. I felt even more appalling, not to say exhausted, and went to bed immediately, becoming worse by the minute. The breathlessness was frightening, and the vomiting and diarrhoea increased during the night - was in a dreadful state. I slept on and off until 2pm on Monday having resolved not to take any more of what I'd been prescribed. The further removed from the previous day and evening's potassium and Ranatadine, the better I became. Is it possible that with a CREST condition, this 'dangerous' level of Potassium does not apply? I never want to go through that again. I haven't felt so bad in years.