Even though the body is potassium depleted, with a typical deficit of around 5 mmol/kg, initial potassium values are usually normal or elevated. Insulin therapy, rehydration and correction of acidosis all cause a decrease in serum potassium and 20-30 mmol potassium/h may be administered once potassium levels are below 5.0 mmol/L, provided renal function is intact. Subsequent potassium administration is guided by frequent concentration measurements; adjuvant oral administration may be used in very mild cases of DKA. It is a frequent practical problem that there may be some delay before values are available from the laboratory; gas analysers that provide instant bedside potassium concentrations greatly facilitate this process.
Bicarbonate use in DKA is a matter of controversy, but it is empirically recommended that 25-50 mmol sodium bicarbonate is given hourly for 1-2 h, if pH is below 7.0. Phosphate deficiency of around 1 mmol/kg is typically present in DKA, but there is no evidence that phosphate supplementation should be given routinely. In patients with severe hypophosphataemia and/or cardiac and skeletal muscle/respiratory weakness, 20-30 mmol of potassium phosphate can be given hourly for 1-2 h.
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