Your astute pharmacy tech checks the labs for a patient. The patient's serum potassium (K+) is listed as 5.4 mEq/L (normal 3.5 - 5.0 mEq/L). At the same time, he gets an order for several IVs - an insulin drip (100 units/100 ml NS, NS with 40 Meq/L K+). The tech states you should call the provider and convince them the patient doesn't need the IV potassium since the patient has a supranormal serum K+ level. You check the computer for other patient labs. The available labs are K+ - 5.4 mEq/L, Glucose - 350 mg/dL, ketones (+++), pH = 7.15).

Do you call the provider or not? Why or why not?

WHY? The patient probably has diabetic ketoacidosis (DKA) based on the low pH, high glucose, + ketones, etc.

        How does the high K+ fit into all this? You thought most DKA patients had LOW serum potassium? Early in the DKA process, as the patient develops the acidosis, hydrogen ions are exchanged with potassium ions to try and maintain electrical neutrality. The acidosis causes a shift of K+ from the intracellular spaces to the serum. DKA patients also tend to be "dry" usually from excessive urinary output and poor oral intake, esp of free water. The shift plus the acidosis plus the volume contraction will cause the serum K+ in the initial stages of DKA to appear elevated. Without supplementation, this is usually followed by a significant fall in serum K+. As you replete the fluid deficit, give insulin (moves K+ back into the cells), correct the acidosis (moves K+ into the cells), you have to give fairly large amounts of IV potassium just to maintain the patient's serum K+. Remember, insulin drives potassium INTO cells and out of the serum. In this case, would probably start insulin at same time or after potassium is repleted. If a patient is already hypokalemic, don't give insulin until potassium is repleted. Be aware of the rate of infusion of potassium too. Monitor the labs (esp K+, pH, glucose, CO2, etc) closely.

Other considerations in treatment of DKA:

- Insulin - a mainstay of therapy. Can only use REGULAR insulin intravenously. Insulin helps lower the serum glucose and stop the oxidation/metabolism of free fatty acids which causes the ketosis. Continue the IV insulin until the serum ketones are negative. If you stop the insulin drip BEFORE the ketosis has resolved, the patient may slide back into DKA. You can usually switch to SQ insulin after the patient starts to eat. A "loading dose" of IV insulin is probably not needed.

- Fluids - LOTS of fluid in needed, depending on the extent and duration of the DKA. Often from 4 to 10 liters of fluid are required. Fluid requirements can be as high as 15 liters but the average deficit is 5 liters.  Remember, glucose is an osmotic diuretic. Start with sodium chloride 0.9% (normal saline) switch to dextrose/saline solutions when the glucose approaches 250 mg/dL. The patient's glucose will correct sooner than the patient's ketosis. If you don't add glucose and continue the insulin drip, the patient may become hypoglycemic.

- Bicarbonate - controversial. Often insulin and fluid replacement will allow the kidney to correct this on it's own. Usually, patients with a serum pH of 7.2 or above do NOT require IV sodium bicarbonate. From 7.2 to 7.0, you may consider addition of sodium bicarbonate to the solutions. Most clinicians would give bicarbonate when the serum pH is below 7.0. Don't mix bicarbonate with phosphate (possible precipitation). The rule of thumb should be "nudge and don't push" when it comes to bicarbonate. Goal is to start (nudge) the pH is the right direction and avoid "overshoot alkalosis". DKA is an "anion gap" metabolic acidosis. There are numerous acronyms to help people remember the causes for these. I use "M U D P I E A C E" which correlates to the following causes: M - methanol, U - uremia, D - DKA, P - paraldehyde, I - ischemia/infection or isoniazid OD, E - ethanol, A - aspirin/salicylates, C - cyanide, E - ethylene glycol (antifreeze).

- Phosphate - also controversial. IF you decide to add (usually when serum PO4 is < 1.5 mg/dL), probably 15 mmoles given as sodium or potassium phosphate is adequate. Remember, every 15 mmoles of phosphate (as potassium phosphate) also provides 22 mEq of potassium. Sodium phosphate yields 22 mEq of sodium per 15 mmoles of phosphate. This can be adjusted based on serum phosphate levels. The body will use phosphate to generate ATP esp when all that glucose gets back into the cells. Do not give with calcium or bicarbonate (possible precipitation). Rates of infusion of IV phosphate solutions should be over at least 6 hours so as to avoid/prevent metastatic calcifications in the tissues.