Differential Diagnosis for Orthostatic Hypotension in an Older Patient Started on Chlorthalidone
- Single most likely diagnosis:
- Dehydration: This is a common side effect of diuretics like Chlorthalidone, especially in older patients who may have decreased thirst sensation and impaired ability to regulate fluids. Dehydration can lead to orthostatic hypotension due to decreased blood volume.
- Other Likely diagnoses:
- Overdiuresis: Similar to dehydration, overdiuresis can lead to orthostatic hypotension by reducing blood volume. This is a direct consequence of the medication's action and can be exacerbated by factors such as excessive dosing or inadequate monitoring.
- Autonomic dysfunction: Older adults may have underlying autonomic nervous system dysfunction, which can be unmasked or worsened by the initiation of antihypertensive therapy, leading to orthostatic hypotension.
- Do Not Miss diagnoses:
- Cardiac causes (e.g., heart failure, cardiac tamponade): Although less likely, cardiac causes of orthostatic hypotension can be life-threatening and must be considered, especially if the patient has risk factors for heart disease.
- Adrenal insufficiency: This is a rare but critical condition that can cause orthostatic hypotension. It might be considered if the patient has other symptoms such as weight loss, fatigue, or hyperpigmentation.
- Rare diagnoses:
- Pheochromocytoma: Although typically associated with hypertension, some patients with pheochromocytoma can experience orthostatic hypotension due to volume depletion or autonomic dysfunction.
- Multiple system atrophy: A rare neurodegenerative disorder that can cause autonomic dysfunction leading to orthostatic hypotension, among other symptoms.