Low potassium causes?

[Inkabalinka]

My DD (15) has been experiencing intermittent pins and needles in her hands and feet, and some weakness in her legs. Her raft of blood tests have just come in indicating everything is normal bar low potassium levels - which does indeed seem to have tingling hands/feet as a symptom.

The text from the GP says to increase potassium-rich foods in her diet. The thing is, her diet is very good and varied, and she already eats large amounts of the foods listed as high in potassium (tomatoes, avocados, bananas, broccoli etc). So why on earth might she be deficient?!

I will attempt to speak to an actual live GP next week, but any insights would be very welcome in the meantime. She's otherwise apparently fit and healthy, though quite anxious about her health!

In a teenage girl with isolated low potassium, I would wonder about bulimia. Could this be a possibility?

Secret vomiting or diarrhoea. Commonest cause in this age group would be an eating disorder.

Otherwise - random meaningless result? If we do enough tests one will eventually come up a little abnormal, not necessarily meaning anything. This is assuming the result is near to the normal range.

Medication can cause it, kidney issues, rare genetic conditions.

Is there going to be a repeat test?

Thanks both for replying. Bulimia is vanishingly unlikely. I know it's a secretive condition but her eating seems really normal in every respect as is her weight, and she is overall a pretty steady, stable character bar a bit of mild health anxiety (which this won't have helped!).

Random meaningless result is useful to know is a possibility, thank you, as Dr Google is a bit alarming! I don't know the exact level but I'm guessing if it had been very abnormal there would be more urgency than just a text telling her to eat more bananas! They did suggest another test in a week.

For anyone in a similar position in future - repeat blood test yesterday showed normal potassium levels, phew. We suspect she was just dehydrated for the first test. It did also show that she is very vitamin D deficient, which might account for her symptoms and is much more explicable given her bat-like tendencies!

Many thanks again for the reassurance, she does not fall far from the tree in health anxiety terms...