Can Primary Aldosteronism Cause Orthostatic Hypotension?
Primary aldosteronism does not typically cause orthostatic hypotension; in fact, it causes hypertension through sodium retention and volume expansion. However, orthostatic hypotension is a recognized clinical feature of pheochromocytoma, which should be considered in the differential diagnosis of secondary hypertension 1.
Understanding the Pathophysiology
Primary aldosteronism produces the opposite hemodynamic effect of what would cause orthostatic hypotension:
Excess aldosterone causes sodium retention, volume expansion, and suppression of plasma renin activity, leading to sustained hypertension rather than postural blood pressure drops 1, 2.
The condition is characterized by autonomous aldosterone production that maintains elevated blood pressure through increased intravascular volume 3.
Hypokalemia may occur if aldosterone excess is prolonged and severe, but this does not typically manifest as orthostatic hypotension 1, 3.
When Orthostatic Hypotension Suggests Alternative Diagnoses
If a patient presents with both hypertension and orthostatic hypotension, consider:
Pheochromocytoma is the key differential diagnosis, as it characteristically presents with orthostatic hypotension alongside hypertension (either paroxysmal or sustained) 1.
Look for additional pheochromocytoma features: paroxysmal "spells" with headache, sweating, palpitations, pallor, and skin stigmata of neurofibromatosis 1.
Screen with 24-hour urinary fractionated metanephrines or plasma metanephrines when orthostatic hypotension accompanies resistant or paroxysmal hypertension 1.
Rare Exception: Coexisting Conditions
One case report describes the association of aldosterone-secreting adenoma with chronic idiopathic orthostatic hypotension, but this represents two separate pathologic processes occurring simultaneously rather than a causal relationship 4.
The authors of this case emphasized that supine hypertension in orthostatic hypotension patients warrants adrenal evaluation, but this does not imply primary aldosteronism causes the orthostatic component 4.
Clinical Pitfall to Avoid
Do not dismiss the diagnosis of primary aldosteronism based on the absence of hypokalemia, as serum potassium levels are rarely low in confirmed cases—hypokalemia is a late manifestation preceded by hypertension 1. However, the presence of orthostatic hypotension should redirect your diagnostic workup toward pheochromocytoma or other causes of dysautonomia rather than primary aldosteronism 1, 5.