HypotensionEdit
Hypotension, or low blood pressure, is a medical condition characterized by blood pressures that are lower than normal and, in some cases, insufficient perfusion of vital organs. It is not always a sign of disease; many healthy people operate with chronically low readings and few symptoms. However, when the drop in pressure is persistent or associated with symptoms such as dizziness, fainting, or confusion, it can signal an underlying problem—ranging from dehydration and medication effects to cardiac or endocrine disorders. In clinical practice, the concern with hypotension lies not simply in the numbers, but in what those numbers mean for tissue perfusion and organ function, particularly in the brain, heart, and kidneys.
The term hypotension encompasses a variety of patterns and causes. Broadly, clinicians distinguish acute hypotension, which can occur suddenly as in bleeding or sepsis, from chronic forms that are persistent over time. A common subtype is orthostatic hypotension, where blood pressure falls when a person stands up or changes position, leading to lightheadedness or fainting. Understanding the different facets of hypotension helps guide evaluation and management, including when to pursue urgent care versus routine monitoring.
Types and etiologies
Orthostatic hypotension
Orthostatic hypotension is diagnosed when blood pressure drops significantly within minutes of standing. Typical criteria describe a systolic decrease of at least 20 mmHg or a diastolic decrease of at least 10 mmHg, accompanied by symptoms. Causes are diverse and may include dehydration, blood loss, age-related changes in the autonomic nervous system, medication effects (such as vasodilators, diuretics, or certain antidepressants), and conditions that impair autonomic function. Some forms, like neurogenic orthostatic hypotension, arise from disorders that damage the autonomic nervous system, including neurodegenerative diseases. See orthostatic hypotension for a broader discussion of this pattern.
Vasovagal and neurally mediated hypotension
Vasovagal syncope, the most common cause of fainting in healthy individuals, involves a reflex that temporarily reduces heart rate and dilates blood vessels, leading to brain hypoperfusion. Neurally mediated hypotension is a broader category that includes vasovagal responses, situational syncope, and other reflex-related blood pressure drops. See vasovagal syncope for more details, and note how transient these episodes can be with proper management and recognition.
Chronic low blood pressure
In some people, a consistently low blood pressure reading is part of their normal physiology. This can occur without symptoms or with mild symptoms that do not impair daily activities. In other cases, chronic hypotension reflects underlying issues such as anemia, hypothyroidism, adrenal insufficiency, chronic heart failure, or kidney disease. Diagnostic workups often include blood tests to assess anemia and endocrine function, as well as evaluation for cardiac or volume status issues. See anemia, hypothyroidism, and adrenal insufficiency for related conditions that can contribute to chronic hypotension.
Acute hypotension and shock
Acute hypotension is a medical emergency in many scenarios. Blood loss from trauma or surgery, severe dehydration, and septic or cardiogenic shock can precipitate dangerous drops in pressure. In these contexts, rapid assessment and resuscitation are critical to restore perfusion and prevent organ injury. See sepsis, cardiogenic shock, and hypovolemia for linked concepts and pathways.
Signs, symptoms, and assessment
Symptoms of hypotension relate to inadequate cerebral and organ perfusion. Common complaints include dizziness, lightheadedness, blurred vision, fatigue, and in some cases fainting or confusion. Some individuals describe weakness, pallor, or cold, clammy skin, especially during episodes where perfusion is compromised. It is important to assess the context—whether the symptoms occur with standing, after meals, during illness, or after medication changes—to guide investigation.
Clinical assessment typically includes repeated blood pressure measurements in different positions (lying, sitting, and standing) and a review of recent fluid intake, medications, and potential blood loss. Diagnostic workups may involve baseline and targeted tests such as blood counts and metabolic panels to evaluate anemia, electrolytes, and kidney function; thyroid tests if endocrine causes are suspected; and an electrocardiogram to screen for rhythm problems. See blood pressure, electrolyte, anemia, thyroid function, and electrocardiogram for related topics.
Diagnosis
Diagnosis hinges on both quantitative measurements and the clinical context. Key elements include: - Confirming a low blood pressure reading, with attention to whether the reading is persistently low or episodic. - Documenting orthostatic changes when symptoms are position-related (as described under orthostatic hypotension). - Identifying symptoms that suggest inadequate organ perfusion. - Investigating potential underlying causes through history, physical examination, and targeted laboratory and testing studies, such as those for anemia, dehydration, endocrine disorders, cardiac disease, or autonomic dysfunction. See orthostatic hypotension, neurogenic orthostatic hypotension, and sepsis for related diagnostic contexts.
Management
Management is tailored to the underlying cause and the severity of symptoms: - Nonpharmacologic measures: adequate hydration, careful management of salt intake if appropriate, and gradual positional changes to reduce symptoms. Compression garments can help in forms related to venous pooling, and physical conditioning may improve tolerance in some patients. See hydration and compression stockings for related interventions. - Adjustment of medications: review and modify drugs that may contribute to low blood pressure, such as certain antihypertensives, diuretics, or vasodilators. - Pharmacologic therapy: in select cases, medications that raise blood pressure or improve autonomic tone may be used, such as midodrine or fludrocortisone, under specialist supervision. See midodrine and fludrocortisone for more information. - Treatment of underlying conditions: addressing dehydration, treating anemia, managing endocrine disorders, and treating cardiac conditions when they contribute to hypotension.
In clinical practice, clinicians balance the goals of maintaining adequate perfusion with avoiding excessive pressure that might cause hypertension-related complications. See cerebral perfusion for a physiological framework of why maintaining tissue perfusion matters.
Prognosis and epidemiology
The prognosis of hypotension depends on the cause and the effectiveness of treatment. Brief, isolated episodes of lightheadedness may improve with simple interventions, whereas persistent hypotension due to chronic disease requires ongoing management. The risk of adverse outcomes, such as falls or organ dysfunction, increases with age, frailty, and the presence of comorbid conditions such as cardiovascular disease, kidney disease, or autonomic disorders. See frailty and cardiovascular disease for broader context on risk factors and outcomes.
Special topics
- Pediatric considerations: hypotension in children has different thresholds and implications than in adults, with emphasis on hydration status, volume depletion, and congenital heart or endocrine issues. See pediatrics and pediatric hypotension for clarifications.
- Autonomic dysfunction: disorders that impair autonomic regulation can produce chronic orthostatic hypotension and complicate management, often requiring multidisciplinary care. See autonomic nervous system and neurogenic orthostatic hypotension.