Low blood pressure is not a diagnosis - it's a symptom. This needs further workup - several have suggested things like thyroid, sodium, glucose, anemia - that all needs to be looked at along with a few other things. You don't just tell someone they have low BP without doing a little exploring - particularly if they aren't tolerating it! Once it's been worked up and nothing is found, then you can call it a primary diagnosis.

And dehydration could be one of the contributors. A chemistry panel and blood count should reveal that though.

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