blood work came back with low carbon dioxide level of 16, 1st time out of normal range. BUN was a little high 30, been this way a while,all other kidney functions fine creatinine level 1.17 gfr 65. I am a 64 year old male with controlled Diabetes a1c 5.4, walk 4 miles everyday weight under control. rest of electrolyte panel in normal range. should I BE worried about low carbon dioxide level? ( breathing lungs fine )