<s>[INST] I am just trying to see if there is a cause for my step mother's pottassium to drop.  She is undergoing the process  of finding out where her cancer has originated but they cannot do any surgerys, etc. until her potassium is in normal range.  I t will come up with medication, but then drop again.  I was just looking for what might be the cause. [/INST] Thanks for your question on HCM.There are many causes for potassium loss in cancer patients.  But the most common ones are.1. Poor oral intake.2. Excess loss in urine.3. Excess loss in stool (diarrhoea).Cancer patients tend to have poor appetite. So their oral intake is low.If cancer has spread in kidney than this csn alter the function of kidney and cause excessive loss in urine.Cancers patients are prone to gastrointestinal infection as their body defence is weakened.  So diarrhoea can be the cause.Better to start potassium supplements. </s>