bombsh3ll

Just wanted to add to this that urine volume and colour are not necessarily good indicators of hydration in POTS patients due to deficient fluid retaining hormones, ie the principle that if your urine is pale you are adequately hydrated cannot automatically be applied to us.

The urine volume/colour method of assessing hydration only holds true in patients who are able to adequately conserve fluid at the renal level. 

B xxx

Thanks for the answer! For me personally the described situation is definitely presyncope rather than vertigo. 

I still believe low stroke volume and cardiac output to be implicated, as I would assume other problems such as local alterations in cerebral blood flow or hyperventilation to not necessarily be posture related & would therefore persist in the supine position. 

My symptoms were also greatly improved by volume expansion.

How I would love to be able to have my supine and upright cardiac output and cerebral blood flow measured!

B xxx