Is orthostatic hypotension one of the symptoms of hypernatremia?

Possibly but unusual. Hypernatremia is usually caused by loss of water in excess of loss of salt. Since one of the signs of dehydration is orthostatic hypotension it is possible. The most common symptom of hypernatremia is confusion/lethargy.
Orthostatic hypotens. Orthostatic hypotension would usually not occur with hypernatremia unless the hypernatremia were the result of dehydration.

Related Questions

In someone with orthostatic hypotension, how long do symptoms like headache last? Permanently until treated, 10 minutes after standing, 5 minutes...?

Up to 5 minutes. The symptoms should normally last up to 5 minutes. However the patient has to be very careful and whenever he gets the symptoms of hypotension he should immediately lie down to avoid loss of consciousness. This will also help getting rid of dizziness and headache. It is always better to treat the cause of hypotension. Read more...