We evaluated how the diagnosis can be missed in a single orthostatic stress test.
Orthostatic tachycardia is more prominent in the morning, but not always.
Symptoms were more frequent in the morning, but not during most tests.
Orthostatic hypotension can be accompanied in postural orthostatic tachycardia syndrome.
We suggest repeated orthostatic stress tests in clinically suspected postural orthostatic tachycardia syndrome patients.