Dehydration: This is often the most common and straightforward cause of orthostatic hypotension, which can also present with elevated blood pressure and heart rate due to the body's attempt to compensate for decreased blood volume.

Anxiety or Panic Attack: Anxiety can cause an increase in blood pressure and heart rate. Orthostatic changes can also occur due to vasovagal responses.
Autonomic Dysfunction: Conditions affecting the autonomic nervous system can lead to orthostatic hypotension and associated tachycardia and hypertension.
Medication Side Effects: Certain medications, such as antidepressants, can cause orthostatic hypotension as a side effect.

Hemorrhage or Severe Blood Loss: Although less common, this is a critical diagnosis to consider, as it can lead to shock and death if not promptly addressed.
Cardiac Tamponade: A life-threatening condition where fluid accumulates in the sac around the heart, impeding its ability to pump blood effectively.
Pulmonary Embolism: Can cause sudden increases in blood pressure and heart rate, along with orthostatic changes due to decreased cardiac output.
Adrenal Insufficiency (Addisonian Crisis): A rare but potentially fatal condition if not recognized and treated promptly.

Pheochromocytoma: A rare tumor of the adrenal gland that can cause episodes of high blood pressure, rapid heart rate, and orthostatic hypotension.
Postural Orthostatic Tachycardia Syndrome (POTS): Characterized by a rapid increase in heart rate and other symptoms upon standing, which can be associated with elevated blood pressure.
Neurocardiogenic Syncope: Involves a reflex of the involuntary nervous system that causes an excessive increase in parasympathetic and a decrease in sympathetic nervous system activity, leading to orthostatic hypotension and bradycardia, though it can initially present with hypertension and tachycardia.