Distinguishing orthostatic hypotension from POTS: A diagnostic challenge in older adults

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Abstract
Orthostatic intolerance represents a broad clinical continuum encompassing orthostatic hypotension (OH) and postural orthostatic tachycardia syndrome (POTS). Although both entities share overlapping manifestations, such as dizziness, presyncope, and palpitations, their underlying autonomic mechanisms differ substantially. Distinguishing between these disorders is crucial yet often diagnostically challenging, particularly in older adults and those with multimorbidity. We report the case of a 78-year-old woman with recurrent episodes of dizziness and presyncope, initially suspected to have orthostatic hypotension and possible arrhythmic etiology. During active standing, her heart rate increased by more than 30 bpm without a significant fall in blood pressure, fulfilling diagnostic criteria for POTS. Continuous 24-hour Holter electrocardiography revealed a tachycardic response to orthostasis without arrhythmogenic events. Comprehensive cardiovascular, neurological and endocrine evaluations were unremarkable, excluding secondary causes of orthostatic intolerance such as anemia, hypovolemia, endocrine disorders, or structural heart disease. The patient’s symptoms improved markedly with non-pharmacological measures, gradual mobilization and low-dose beta-blocker therapy. This case underscores the diagnostic complexity within the orthostatic intolerance spectrum and highlights the need for meticulous assessment of autonomic responses. OH and POTS may appear clinically similar but differ fundamentally in pathophysiology. OH is characterized by impaired vasoconstriction and an inadequate, often blunted heart rate response due to autonomic dysfunction, whereas POTS involves excessive sympathetic activation with a pronounced tachycardic response. Recognition of POTS in the older adults is critical, as misclassification can delay management. Comprehensive autonomic testing and individualized therapy remain key to optimizing outcomes.

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