01OverviewDefinition, clinical context and the essential points that orientate the chapter.
Standing shifts blood to the legs and splanchnic circulation. Baroreceptors normally increase sympathetic vasoconstriction and heart rate and reduce vagal tone. Orthostatic hypotension occurs when volume, cardiac output, vascular tone or autonomic compensation is inadequate. Neurogenic failure is only one category; dehydration, blood loss, adrenal disease, sepsis, arrhythmia and medicine effect must be assessed according to tempo and physiology.
The symptom–pressure relationship is central. A person can meet numerical criteria without symptoms, while a brief unmeasured early fall can cause symptoms despite normal three-minute values. Delayed orthostatic hypotension emerges after three minutes and may require longer standing or tilt testing. Postural tachycardia syndrome involves excessive heart-rate rise without the defining pressure fall and requires a separate specialist framework; it should not be diagnosed from one dehydrated acute-illness measurement.
Neurogenic autonomic failure is usually multisystem. Parkinsonian movement with early severe autonomic symptoms can suggest multiple system atrophy; length-dependent sensory loss suggests diabetic or amyloid neuropathy; dry mouth and eyes, tonic pupils, bowel dysmotility or rapid subacute failure raises immune autonomic ganglionopathy; cord lesions create disruption and, above T6, risk autonomic dysreflexia. Examination includes cognition, pupils, parkinsonism, gait, peripheral nerves and skin and sweating changes.
Treatment aims to reduce symptoms, syncope and injury rather than normalise every pressure. Measures conflict: fluids and pressors raise standing pressure but may worsen supine hypertension, heart failure and nocturnal natriuresis. A written plan should specify morning and post-dose monitoring, safe resting posture, last dose timing, illness and heat adjustments and who reviews electrolytes or renal function. Complex autonomic failure belongs with neurology, cardiology, geriatrics or specialist autonomic services.
Key points
- Orthostatic hypotension is a sustained fall of at least 20 mmHg systolic or 10 mmHg diastolic within three minutes of standing or head-up tilt; larger systolic thresholds may be used when supine hypertension is present.
- Measure after adequate supine rest and again after standing, recording symptoms, pulse and exact timing. If the patient cannot stand safely, use the locally accepted lying-to-sitting modification and state the limitation.
- Ask about light-headedness, dim vision, coat-hanger neck pain, weakness, cognitive slowing, falls, syncope, meals, heat, exercise, urination and time of day. Patients with chronic autonomic failure may report fatigue rather than dizziness.
- Review volume loss, anaemia, infection, cardiac disease and medicines before diagnosing neurogenic failure. Diuretics, antihypertensives, nitrates, alpha blockers, dopaminergic medicines, antidepressants, opioids and alcohol can contribute.
- A blunted heart-rate rise during a significant pressure fall can support neurogenic orthostatic hypotension, while marked tachycardia suggests preserved reflexes or a different orthostatic syndrome; beta blockers and pacing confound this distinction.
- Look for the rest of the autonomic phenotype: urinary retention or urgency, constipation, erectile dysfunction, sweating change, heat intolerance, pupillary symptoms, gastroparesis and postprandial hypotension.
- Neurological causes include Parkinson's disease, multiple system atrophy, pure autonomic failure, diabetic and amyloid neuropathy, spinal-cord disease and immune or paraneoplastic autonomic neuropathy.
- First-line treatment combines medication rationalisation, adequate fluid and salt only when safe, slow staged rising, physical counter-pressure manoeuvres, smaller meals, heat avoidance, head-up sleeping and compression selected for the individual.
- Supine hypertension commonly coexists with neurogenic orthostatic hypotension. Check lying as well as standing pressures and avoid taking pressor medicine close to lying down or bedtime.
- Midodrine can improve standing pressure but may cause supine hypertension, piloerection, scalp tingling and urinary retention; it requires specialist or experienced prescriber oversight and timed monitoring.
- Fludrocortisone expands volume but is off-label for postural hypotension in many UK contexts and can cause oedema, hypokalaemia, heart failure and supine hypertension; it is not benign salt replacement.
- Driving, bathing, toileting and night-time falls need explicit advice. Treat functional risk and triggers rather than pursuing a normal clinic blood pressure target that worsens standing symptoms.
02AetiologyUnderlying causes, associations and risk factors, with why each one matters.
Volume, cardiac and medicine effects
Dehydration, blood loss, anaemia, sepsis, reduced cardiac output and vasodilating or diuretic medicines can lower standing pressure without primary neurological autonomic disease.
Neurodegenerative autonomic failure
Parkinson disease, multiple-system atrophy and pure autonomic failure impair central or peripheral sympathetic control, often alongside parkinsonism, urinary symptoms, REM sleep behaviour disorder or stridor.
Peripheral autonomic neuropathy
Diabetes, amyloid, immune ganglionopathy and paraneoplastic neuropathy can damage sympathetic, parasympathetic and sensory fibres, producing multisystem autonomic symptoms.
Spinal and secondary causes
Spinal cord lesions interrupt descending autonomic pathways and can also predispose to autonomic dysreflexia, while endocrine and metabolic disorders provide important non-neurological alternatives.
03PathophysiologyThe causal sequence from the underlying abnormality to symptoms and harm.
- 1Orthostatic blood pooling
Standing shifts blood into leg and splanchnic capacitance vessels, transiently reducing venous return, stroke volume and arterial pressure.
- 2Compensatory reflex failure
Impaired baroreceptor signalling, sympathetic vasoconstriction or heart-rate response prevents adequate restoration of pressure, especially after meals, heat, exertion or prolonged recumbency.
- 3Cerebral hypoperfusion
Reduced standing pressure lowers brain perfusion, causing dim vision, cognitive slowing, weakness, presyncope or syncope until recumbency restores venous return.
- 4Supine pressure excess
Loss of baroreflex buffering and pressor treatment may cause hypertension when lying flat, promoting nocturnal natriuresis and worsening morning volume depletion.
04Clinical features and red flagsSymptoms, examination findings, patterns of presentation and time-critical warnings.
A reproducible sustained pressure fall with orthostatic symptoms, limited compensatory tachycardia and urinary, bowel, sweating or parkinsonian features supports autonomic failure after volume and medicine causes are addressed.
Recent vomiting, diarrhoea, bleeding, fever, diuresis or poor intake with thirst, weight loss and tachycardia suggests reduced circulating volume. Oedema does not exclude low effective arterial volume.
Collapse during exertion or while supine, palpitations, chest pain, family sudden death, structural heart disease or an abnormal ECG is not explained safely by an orthostatic reading and needs urgent cardiac assessment.
Parkinsonism or cerebellar dysfunction with early prominent urinary, erectile and orthostatic failure, stridor or poor levodopa response raises atypical parkinsonism and requires specialist review.
Orthostatic hypotension with distal sensory loss, reduced reflexes, gastroparesis, diarrhoea or constipation, sweating change and erectile dysfunction occurs in diabetes, amyloid and other generalised neuropathies.
High blood pressure when recumbent, often nocturnal, can coexist with severe standing hypotension and be worsened by pressors. It contributes to nocturnal diuresis and limits treatment escalation.
A person with a lesion usually at or above T6 develops abrupt hypertension, pounding headache, flushing or sweating above the lesion, piloerection and sometimes bradycardia from bladder, bowel or skin stimulation.
05InvestigationsWhat to request, why it matters and how to interpret it.
Read from the initial assessment onwards. Tests may run in parallel in urgent care; first-line, preferred, confirmatory, definitive and gold-standard labels appear only when the chapter explicitly states them.
- 01
Lying and standing blood pressure with pulseFirst step - Why
- Demonstrate timing and magnitude of orthostatic change and relate it to symptoms and chronotropic response.
- Interpretation and limitations
- Rest supine, then record promptly and through at least three minutes of standing as safe. State arm, device, timing and symptoms; repeat on another occasion or after meals when history remains convincing.
- 02
Twelve-lead ECG and cardiac evaluation - Why
- Detect conduction disease, arrhythmia, ischaemia or structural clues that make syncope cardiac rather than autonomic.
- Interpretation and limitations
- A normal resting ECG does not exclude intermittent arrhythmia. Event monitoring and echocardiography are selected from exertional symptoms, examination and history, not ordered for every dizzy spell.
- 03
FBC, U&E, glucose, calcium and targeted endocrine tests - Why
- Identify anaemia, dehydration, electrolyte disturbance, diabetes, renal impairment and selected adrenal or thyroid causes.
- Interpretation and limitations
- Use the acute context and medication changes. Check potassium and renal function before and during fludrocortisone, and do not diagnose adrenal failure from a random cortisol without appropriate interpretation.
- 04
Medication and volume review - Why
- Find reversible hypotensive, sedative and autonomic effects and quantify fluid, salt, alcohol and meal triggers.
- Interpretation and limitations
- Do not stop cardioprotective or neuropsychiatric medicines indiscriminately. Agree staged changes with the indication-holder and repeat standing observations and symptoms after each intervention.
- 05
Tilt-table and continuous beat-to-beat testing - Why
- Characterise delayed orthostatic hypotension, reflex syncope and postural tachycardia when bedside assessment is inconclusive.
- Interpretation and limitations
- Protocols and thresholds are specialist-specific. Reproduced symptoms and haemodynamics matter; a provoked result must be reconciled with spontaneous events and medication state.
- 06
Specialist autonomic function tests - Why
- Assess cardiovagal, adrenergic and sudomotor pathways in suspected generalised or immune autonomic failure.
- Interpretation and limitations
- Deep breathing, Valsalva, sweat and catecholamine methods require specialist laboratories and medication preparation. Results localise physiology but do not alone establish degenerative or autoimmune cause.
06Differential diagnosisRealistic alternatives and the features that help distinguish them.
Vasovagal or cardiac syncope
Prodromal warmth, nausea and a stereotyped trigger favour reflex syncope, while exertional events, palpitations or abnormal ECG findings raise arrhythmic or structural cardiac disease.
Postural tachycardia syndrome
Orthostatic symptoms with excessive heart-rate rise but without the defining sustained pressure fall suggest a separate syndrome after dehydration and acute illness are excluded.
Vestibular or gait disorder
Vertigo, nystagmus or persistent imbalance unrelated to measured pressure change supports vestibular or neurological gait disease rather than cerebral hypoperfusion.
Adrenal or systemic illness
Weight loss, pigmentation, electrolyte disturbance, fever or ongoing volume loss suggest endocrine, infectious or gastrointestinal disease and should prevent premature attribution to neurogenic failure.
07ManagementImmediate care, first-line treatment, alternatives and escalation.
01Postural dizziness or collapseProve physiology and exclude dangerFirst stepLight-headedness, visual dimming, weakness, fall or transient loss of consciousness occurs during standing or soon after rising.+
- 1Check ABCDE and glucose when acute, obtain event and witness history, ECG, injury and red flags, and measure properly timed supine and standing pressure and pulse when safe.
- 2Treat bleeding, dehydration, infection, arrhythmia or endocrine crisis and review medicines; route exertional, supine, cardiac or focal neurological features to emergency specialist care.
- 3If orthostatic hypotension persists, implement individual non-drug measures and arrange follow-up or autonomic assessment rather than relying on one asymptomatic clinic reading.
02Neurogenic chronic failureBalance standing function and supine riskRepeated symptomatic orthostatic falls coexist with blunted pulse response and neurological, urinary, bowel or sweating dysfunction.+
- 1Map the full autonomic and neurological phenotype, reconcile medicines, check cardiovascular and laboratory contributors and record lying, standing, meal-related and bedtime pressures.
- 2Optimise fluids, salt when safe, staged rising, counter-pressure manoeuvres, compression and head-up sleeping, then consider midodrine or fludrocortisone through an experienced prescriber if disability remains.
- 3Set symptom and falls goals and monitor supine blood pressure, urine retention, oedema, electrolytes and organ function, reducing or retiming treatment when harms outweigh standing benefit.
03Autonomic dysreflexiaRemove the trigger and lower pressure safelyA person with high spinal-cord injury develops sudden hypertension, headache, flushing, sweating, anxiety, visual change or bradycardia.+
- 1Sit the person upright, lower legs if feasible, loosen tight clothing or devices, call urgent spinal and medical help and monitor blood pressure repeatedly while maintaining safety.
- 2Check the urinary system first for catheter kinks, obstruction or a full bladder using the trained spinal protocol, then consider bowel impaction, skin injury, pain and other noxious stimuli below the lesion.
- 3If hypertension persists, give the rapid-acting medicine specified in the person's emergency and local spinal plan, continue trigger removal and observe for recurrence and hypotension after resolution.
Key medicines and prescribing safety2 treatments · regimens, roles and cautions+
Midodrine for disabling neurogenic orthostatic hypotension
An experienced prescriber may start 2.5 mg orally three times daily during waking upright hours and titrate weekly to response, commonly up to 10 mg three times daily, keeping the last dose at least four hours before bed.Check supine hypertension, urinary retention, bradycardia, severe heart or renal disease and interacting vasoconstrictors; patients must avoid lying flat after doses and stop or seek review for severe headache or chest symptoms.
Fludrocortisone for selected orthostatic hypotension
When specialist or experienced review supports off-label use, start 50–100 micrograms orally each morning and titrate cautiously to symptoms and monitoring rather than a normal standing-pressure target.Monitor supine blood pressure, potassium, renal function, weight and oedema; avoid or use extreme caution in heart failure, significant renal disease and uncontrolled hypertension, and reassess long-term corticosteroid effects.
08ComplicationsImportant consequences, why they occur and why they matter clinically.
Syncope, falls and injury
Transient cerebral hypoperfusion causes collapse, fractures and fear of standing, while nocturnal toileting and coexisting gait disease amplify risk.
Functional restriction and deconditioning
Avoidance of upright activity reduces mobility, self-care and exercise tolerance, creating muscle loss and further orthostatic intolerance unless rehabilitation is paced safely.
Supine hypertension injury
Persistent recumbent hypertension may contribute to cardiovascular, renal and cerebrovascular harm and can worsen overnight fluid loss, complicating otherwise helpful pressor therapy.
Multisystem autonomic morbidity
Urinary retention, constipation, sweating disturbance, erectile dysfunction and gastroparesis can cause infection, impaction, malnutrition, skin problems and substantial quality-of-life loss.
09Monitoring and follow-upTreatment response, safety checks and longer-term review.
- Maintain a symptom, fall and blood-pressure diary including supine, pre-dose, post-dose, standing, post-meal and bedtime readings tailored to the treatment plan.
- Review pulse response, hydration, weight and new cardiac symptoms after illness or medicine changes because the mechanism of hypotension may shift.
- Check potassium and renal function after starting or increasing fludrocortisone and monitor oedema and breathlessness for volume-related harm.
- Assess urinary retention and supine hypertension after midodrine, ensuring the final daily dose remains sufficiently separated from lying down.
- Track functional goals—safe showering, toileting, walking and reduced falls—rather than escalating medicine solely to improve a numerical reading.
- Provide an emergency plan for autonomic dysreflexia, syncope with injury, focal neurological symptoms, chest pain and sustained severe hypertension.
10Special situationsVariants, exceptions and circumstances that change the usual approach.
Symptoms may be cognitive
Reduced cerebral perfusion can produce fatigue, shoulder-neck ache or slowed thinking rather than classic light-headedness. Asking only about dizziness under-recognises orthostatic disability.
Heart rate is contextual
A small pulse rise during a large pressure fall supports autonomic failure, but beta blockade, intrinsic conduction disease and pacing can blunt the response independently.
Meals redistribute blood
Splanchnic pooling after carbohydrate-rich or large meals can worsen neurogenic hypotension. Smaller meals and planned activity timing may help more than indiscriminate drug escalation.
Supine pressure drives nocturia
Recumbent hypertension promotes pressure natriuresis overnight, reducing morning volume and worsening standing symptoms. Head-up sleeping can address both sides of the cycle.
Compression must reach abdomen
Venous pooling is substantially splanchnic. Abdominal binders or waist-high garments may be more effective than knee-length stockings, provided skin, arterial and comfort risks are assessed.
Dysreflexia reverses the problem
High cord lesions can cause episodic dangerous hypertension from an unseen bladder, bowel or skin trigger. It is not simply another form of low autonomic blood pressure.
11Common pitfallsFrequent interpretation and management errors.
- 01
Measuring only sitting blood pressure and declaring postural hypotension absent.
- 02
Diagnosing autonomic failure during dehydration without repeating physiology after correction.
- 03
Stopping several essential medicines at once, making benefit and harm impossible to attribute.
- 04
Prescribing pressor therapy without checking supine and bedtime blood pressure.
- 05
Taking midodrine at bedtime and worsening nocturnal hypertension.
- 06
Increasing salt and fluid without considering heart failure, kidney disease and severe hypertension.
- 07
Treating autonomic dysreflexia as anxiety while a blocked catheter or bowel trigger persists.