what is the cause of the hypokalemia in the first place? I don't know how hypokalemia itself would further hypokalemia unless it involved something like an arrhythmia and heart failure so you get a less effective blood flow to the kidney.
In this case you get and upregulation of aldosterone which will preferentially reabsorb sodium at the expense of K+ in principal cells of the collecting tubule. When K+(now being filtered into the collecting tubule lumen) reaches the intercalated cells it gets reabsorbed by the K+/H+ antiporter. But now you get H+ being lost in the urine as well. Overall the intercalated cell cannot reabsorb enough K+ and you get a total loss of K+ and H+.
Hope this helps.
