First step is a 24 hour urine for volume, creatinine, sodium and potassium with a concomitant BMP.
=> If the 24 hour urine potassium is greater than 25 meq/24 hr, there is a least a contribution from some type of urinary leak (especially if measured in the face of hypokalemia), please submit consult renal.
=> If less than 25 meq/24 hr, look for non-renal causes of hypokalemia.