Skip to textbook content
Doctor’s PassportTextbook
TopicsAll topics

Loading topic navigation…

Textbook navigation
TopicsAll topics

Loading topic navigation…
← Medicine of older adults indexChapter sections
OverviewAetiologyPathophysiologyClinical features and red flagsInvestigationsDifferential diagnosisManagementComplicationsMonitoring and follow-upSpecial situationsCommon pitfallsQuestionsSources
Full textbook13 sectionsOpen only what you need
Educational draft · awaiting clinical reviewThe full textbook explains uncertainty but does not replace live national or local guidance, specialist advice, or current prescribing information.

Atypical presentation of illness in older adults

Medicine of older adults · UK scope · Sources checked 27 Aug 2026 · Clinical review pending

RapidFull
!
Non-specific does not mean low risk

A fall, delirium, immobility, poor intake, incontinence, weakness or carer concern may be the only early sign of sepsis, stroke, myocardial infarction, bleeding, fracture, hypoglycaemia, hypoxia or abdominal catastrophe.

Action: Use ABCDE, glucose, observations and full examination immediately, establish the time course and baseline through collateral, reconcile medicines, investigate high-consequence causes in parallel and repeat assessment when initial signs are muted or the functional trajectory worsens.

Overview

Recognise non-specific and muted presentations of serious illness, compare current function with a reliable baseline, avoid diagnostic overshadowing by age or frailty, and use disciplined broad-to-focused assessment without reflex overtesting.

Begin with the change, not the age. Ask the person and collateral witness for the last known well time, symptom sequence, falls or collapse, intake, urine and bowel change, medicines and baseline cognition and daily function. A relative's statement that they are not themselves can be high-value evidence even when initial observations appear normal.

Perform ABCDE, capillary glucose and a head-to-toe examination. Look for respiratory effort and oxygenation, pulse irregularity, perfusion, hydration, focal neurology, meningism, injury, pressure areas, abdominal distension and tenderness, retention, faecal loading and skin infection. Measure lying and standing blood pressure only when safe and relevant, without delaying resuscitation.

Delirium may be hyperactive, hypoactive or mixed. Use 4AT, obtain baseline cognition and search several simultaneous precipitants: infection, hypoxia, pain, constipation, retention, dehydration, metabolic disorder, medicine toxicity, withdrawal and environmental disruption.

Practice

Two practice questions

Your practice draft is saved in this browser.

Question 1 of 2
0 correct
Medicine of older adultsOriginal SBA

Positive urine test in delirium

A care-home resident develops acute delirium and cough. Urine dipstick is positive for leucocytes and nitrite, but there are no urinary symptoms; oxygen saturation is 89% and right basal crackles are present. What is the best interpretation?

Choose one answer, then submit
← Rapid synopsisBack to overviewAll Medicine of older adults topics →
Sources and review status5 sources · checked 27 Aug 2026 · clinical review pending+
Sources

Sources and review status

National guidance is shown before implementation-dependent detail. Apply principles in context and verify current guidance when a decision affects care. Source check completed 27 Aug 2026; clinical approval remains outstanding.

  • British Geriatrics Society CGA resourceAtypical syndromes, baseline function and integrated reassessment.
  • NICE CG103 delirium recommendationsDelirium assessment, causes and multicomponent care.
  • NICE NG51 sepsis recommendationsRisk assessment, physiology, investigations and urgent treatment.
  • NICE NG109 lower urinary tract infectionOlder-adult urine testing and asymptomatic bacteriuria safeguards.
  • NICE NG185 acute coronary syndromesECG, troponin and acute coronary assessment and treatment.

Editorial contact: Doctor’s Passport editorial team. Source-check date is separate from clinical approval. Report a content problem · Content changes

Authoring stateComplete draftClinical stateAwaiting reviewJurisdictionUnited Kingdom
Do not
stop after finding one plausible factor; older adults commonly have multiple interacting causes.

Infection assessment is source-led. Obtain cultures before antibiotics when this creates no harmful delay and use sepsis physiology and organ dysfunction to set urgency. Absence of fever is not reassuring, but neither is a positive urine dipstick proof of urinary infection. Asymptomatic bacteriuria is common; unnecessary antibiotics can cause adverse effects, resistance and Clostridioides difficile.

Falls require reconstruction. Determine trip, prodrome, loss of consciousness, seizure features, palpitations, post-event confusion, head strike and ability to rise. Examine gait, injuries, neurology and cardiovascular system and review postural and sedative or hypoglycaemic medicines. An unwitnessed fall in an anticoagulated person or new inability to weight bear lowers the threshold for imaging.

Cardiovascular and abdominal emergencies can be quiet. Consider ECG and serial troponin for compatible dyspnoea, nausea, sweating, syncope or unexplained decline. Bowel obstruction, ischaemia, perforation, cholecystitis and retention may produce delirium or anorexia with limited pain. Repeat abdominal examination and use lactate and imaging according to probability, recognising that normal early tests may not end the assessment.

Review every medicine, including recent starts, dose changes, adherence and non-prescription products. Link sedatives, opioids and anticholinergics to arousal and retention; insulin and sulfonylureas to hypoglycaemia; antihypertensives and diuretics to hypotension and renal injury; anticoagulants to occult bleeding. Adjust for current kidney and liver function and avoid abrupt withdrawal where dangerous.

Order tests to address explicit questions. Common early studies may include FBC, renal and liver profile, calcium, CRP, glucose, ECG and targeted imaging or microbiology, but presentation determines selection. Interpret modest abnormalities against baseline and medicines. Repeat observations and examination when trajectory and initial results disagree rather than escalating incidental findings.

Treat the cause and prevent the cascade simultaneously: oxygen when indicated, fluid with reassessment, analgesia, nutrition, glasses and hearing aids, orientation, sleep protection, early mobilisation, thrombosis and pressure prevention and removal of unnecessary catheters. Avoid sedating distress before pain, retention, constipation and fear are addressed.

Before discharge, explain the working diagnosis and residual uncertainty and compare cognition, intake, mobility and ADLs with baseline. Confirm medicine changes, rehabilitation, care support and safety-net triggers. Persistent unexplained functional loss warrants senior reassessment rather than being relabelled new frailty.

Key points

  • Atypical presentation means the initial symptom does not localise the cause: common signals are delirium, falls, immobility, incontinence, anorexia, fatigue and functional decline.
  • First-line action is ABCDE, observations, capillary glucose, pain and full examination while collateral establishes exact onset and stable baseline.
  • Serious infection can occur without fever or leukocytosis; use physiology, organ dysfunction, source assessment and trajectory rather than one absent classic sign.
  • Delirium is acute brain failure and demands a cause search. Known dementia increases risk but never explains a sudden fluctuation by itself.
  • Acute coronary syndrome may present with dyspnoea, weakness, nausea, syncope or delirium; obtain ECG and troponin when the context supports it.
  • A fall is an event, not a diagnosis. Ask what happened before, during and after and examine for syncope, stroke, infection, medicine harm and injury.
  • Reconcile recent prescriptions, missed doses and renal function early; a medicine that was previously tolerated can become toxic during dehydration or acute kidney injury.
  • Do not diagnose urinary infection from bacteriuria or a positive dipstick alone in an older adult without compatible urinary or systemic evidence.
  • Use targeted testing from competing high-consequence hypotheses and repeat examination; indiscriminate panels create incidental findings and treatment harm.
  • Track function and cognition as vital outcomes. Failure to regain expected mobility or intake should reopen the diagnosis before discharge.

Aetiology

01

Acute organ disease

Infection, vascular events, heart failure, arrhythmia, bleeding, fracture and abdominal or urinary emergencies commonly present through functional or cognitive change rather than a localising symptom.

02

Metabolic and endocrine disturbance

Hypoglycaemia, hyperglycaemia, sodium and calcium disorders, renal or hepatic failure, thyroid disease and dehydration can produce weakness, falls, reduced intake or delirium.

03

Medicine and substance effects

Sedatives, anticholinergics, opioids, antihypertensives, insulin, anticoagulants, withdrawal and recent dose changes can cause non-specific decline or amplify otherwise modest illness.

04

Environmental and social stress

Care disruption, sleep loss, unfamiliar surroundings, sensory deprivation, malnutrition and carer breakdown can precipitate decline but should be considered alongside, not instead of, medical disease.

Pathophysiology

  1. 1
    Reduced physiological reserve

    Limited cardiovascular, renal, neurological and muscular reserve means a small stressor can cross functional thresholds and produce disproportionate dependency before organ-specific symptoms become prominent.

  2. 2
    Altered inflammatory response

    Immunosenescence, frailty and medicines can blunt fever, tachycardia, leukocytosis and pain, so absence of classic inflammatory signs lowers sensitivity but never excludes serious infection.

  3. 3
    Brain as vulnerable organ

    Systemic inflammation, hypoxia, metabolic change, pain and drugs disrupt attention and arousal, making delirium a frequent final common pathway of extracranial illness.

  4. 4
    Homeostatic cascade

    Illness causes anorexia, dehydration, immobility and medication disruption, which then create kidney injury, constipation, pressure injury, thrombosis and further cognitive and functional loss.

  5. 5
    Communication and perception barriers

    Cognitive, hearing, visual, language and neuropathic impairment can alter symptom recognition and reporting, while clinicians may unconsciously discount complaints because of age or disability.

Clinical features and red flags

Delirium as presentationRed flag

Acute inattention, fluctuation or altered arousal may be the only visible sign of systemic infection, hypoxia, pain or metabolic disease.

Fall as presentation

A fall can follow syncope, arrhythmia, stroke, hypoglycaemia, infection, drug effect or fracture and requires event reconstruction.

Functional decline

New inability to cook, walk, toilet or take medicines can precede classic symptoms and quantifies physiological impact.

Muted infection response

Serious infection may lack fever, tachycardia or leukocytosis, especially with frailty, immune suppression or rate-limiting medicines.

Silent cardiopulmonary diseaseRed flag

Dyspnoea, nausea, fatigue, collapse or confusion can replace chest pain in acute coronary, arrhythmic and thromboembolic disease.

Diagnostic overshadowing

A known dementia, frailty or care-home residence is used as the explanation before acute and reversible causes are assessed.

Red flags requiring action

  • New delirium, drowsiness or agitation with physiological change requires urgent infection, hypoxia, metabolic, neurological, pain and medicine assessment.
  • Unexplained fall with syncope, chest discomfort equivalent, palpitations, focal neurology, head injury or inability to weight bear needs emergency evaluation.
  • New breathlessness, fatigue, nausea, diaphoresis or confusion may represent acute coronary syndrome without classic central chest pain.
  • Poor intake with hypotension, oliguria, hypoglycaemia, hyperglycaemia, electrolyte disturbance or acute kidney injury can deteriorate rapidly.
  • Abdominal distension, vomiting, altered bowel habit, guarding, retention or unexplained delirium may signal obstruction, perforation, ischaemia or urinary pathology despite modest pain.
  • A frailty or dementia diagnosis must not close the differential when change is acute, focal, progressive or inconsistent with baseline.

Investigations

  1. 01
    ABCDE, glucose and observationsFirst step
    Why
    Detect immediate physiological and metabolic threat.
    Interpretation and limitations
    Treat abnormalities while repeating trends; normal temperature or one reassuring observation set does not exclude evolving disease.
  2. 02
    Collateral timeline and baseline
    Why
    Separate acute change from chronic vulnerability.
    Interpretation and limitations
    Record last known well, event sequence, baseline cognition, ADLs and IADLs, intake, continence, medicines and carer concern.
  3. 03
    Full repeated examination
    Why
    Localise disease that the history does not reveal.
    Interpretation and limitations
    Include neurology, cardiopulmonary, abdomen, bladder, injury, skin, hydration, pain, feet and pressure areas and repeat when trajectory changes.
  4. 04
    Medication reconciliation
    Why
    Identify toxicity, withdrawal and prescribing cascade.
    Interpretation and limitations
    Compare multiple sources, recent changes, missed doses and OTC products and interpret each against renal, hepatic, pressure and glucose status.
  5. 05
    Targeted laboratory testing
    Why
    Test several competing high-consequence clinical hypotheses.
    Interpretation and limitations
    Select blood count, renal, liver, calcium, glucose, inflammation, troponin, thyroid, cultures and urinalysis according to presentation and baseline.
  6. 06
    ECG and presentation-led imaging
    Why
    Find silent vascular, cardiac, pulmonary, abdominal and traumatic disease.
    Interpretation and limitations
    Choose CT, radiograph, ultrasound or other imaging from event, focal findings, anticoagulation, injury and failure to improve; avoid routine scanning without a question.
  7. 07
    4AT and functional reassessment
    Why
    Measure brain and whole-person response.
    Interpretation and limitations
    Screen delirium and repeatedly compare alertness, attention, mobility, intake and self-care with baseline after treatment.

Differential diagnosis

01

Primary neurological event

Stroke, seizure, subdural haemorrhage and neurodegeneration can cause falls or confusion; focal findings, headache, anticoagulation, trauma and time course guide urgent imaging.

02

Systemic infection or inflammation

Respiratory, urinary, skin, abdominal and device infection may be afebrile, but asymptomatic bacteriuria is common and must not become the default explanation for delirium.

03

Cardiopulmonary disease

Acute coronary syndrome, arrhythmia, heart failure, pulmonary embolism and respiratory failure can manifest as weakness, falls, nausea or confusion with little reported pain.

04

Medication or metabolic toxicity

Hypoglycaemia, electrolyte disturbance, renal drug accumulation, anticholinergic load, opioid toxicity and withdrawal are rapidly testable causes that often coexist with acute disease.

05

Functional and psychosocial cause

Depression, pain, sensory loss, malnutrition and care failure can produce decline, but a new presentation requires medical exclusion before diagnostic closure.

Management

01First-line acute sequenceStabilise, date the change and test serious hypothesesFirst stepFirst lineAn older adult presents with a fall, confusion, weakness, poor intake or functional loss.+
  1. 1Perform ABCDE, glucose, observations and immediate treatment while obtaining last-known-well and baseline collateral.
  2. 2Complete full examination and medicine reconciliation and investigate several plausible high-consequence causes in parallel.
  3. 3EscalationRepeat physiology, cognition and function and escalate when trajectory remains unexplained despite initially modest findings.
02Delirium routeTreat brain failure and its interacting causesAcute fluctuation, inattention or altered arousal is present.+
  1. 1Use 4AT, ensure safety and identify hypoxia, infection, pain, retention, constipation, metabolic and medicine precipitants.
  2. 2Treat causes and provide orientation, sensory support, hydration, sleep protection and mobilisation without unnecessary restraint or sedation.
  3. 3Monitor course and investigate persistent or focal change for neurological, malignant or other missed disease.
03Non-response routeReopen the diagnosis before accepting declineLaboratory values improve but function, intake or cognition does not.+
  1. 1Repeat history, examination, observations and medicine review and verify that treatment and rehabilitation were delivered.
  2. 2Reconsider occult injury, stroke, embolism, abdominal disease, depression, sensory loss, malnutrition and care factors.
  3. 3EscalationObtain senior and MDT review, update goals and support and communicate residual uncertainty and escalation triggers.

Complications

01

Delayed diagnosis and death

Attributing non-specific change to age, dementia or frailty can postpone antibiotics, reperfusion, surgery or treatment of metabolic and cardiopulmonary emergencies.

02

Delirium and persistent decline

Untreated illness and hospital stress can cause prolonged delirium, deconditioning and new care dependency even after the original physiology improves.

03

Iatrogenic cascade

Indiscriminate tests, catheters, bed rest, sedatives and treatment of colonisation can cause infection, adverse drug effects, immobility and further diagnostic confusion.

04

Falls and pressure harm

Weakness and immobility lead to recurrent falls, fracture, pressure injury, venous thromboembolism and aspiration unless prevention and mobilisation begin alongside diagnosis.

05

Unsafe transition

Discharge after laboratory improvement without recovery, explanation or support for new functional loss risks readmission, missed medicines and carer breakdown.

Monitoring and follow-up

  • Trend observations, urine output and disease-specific tests together with 4AT, alertness, intake, mobility and ADL recovery.
  • Repeat examination after analgesia, hydration and delirium change; evolving abdominal, neurological and injury signs may become clearer.
  • Review medicines daily during renal, hepatic, pressure or glucose instability and document restart criteria for temporarily held treatment.
  • Remove catheters and unnecessary monitoring promptly and track pressure, thrombosis, aspiration and deconditioning prevention.
  • At transition compare with dated baseline, confirm the explanatory diagnosis and safety net any persistent or unexplained functional gap.

Special situations

Collateral can be a vital sign

A reliable witness describing abrupt change may reveal severity before conventional observations become abnormal.

Afebrile is not uninfected

Older physiology and medicines may mute fever, but source evidence and organ dysfunction still determine treatment.

Bacteriuria can distract

Colonisation is common and may divert attention from pneumonia, retention, medicines or stroke.

A fall needs a verb before it

Tripped, fainted, collapsed, was pushed or lost balance generate different investigations.

Recovery tests the diagnosis

Failure of cognition or function to improve as predicted is evidence that the cause or intervention may be incomplete.

Frailty modifies, never explains

It predicts vulnerability to the stressor but does not identify which stressor occurred.

Common pitfalls

  1. 01

    Writing mechanical fall without reconstructing prodrome, consciousness, injury and contributing illness.

  2. 02

    Diagnosing urinary infection from a positive dipstick in delirium without compatible source evidence.

  3. 03

    Using absent fever or normal leukocytes to exclude serious infection.

  4. 04

    Attributing sudden decline to dementia or frailty before checking acute and reversible causes.

  5. 05

    Ordering indiscriminate tests, then treating incidental abnormalities while the clinical trajectory worsens.

  6. 06

    Discharging after biochemical recovery despite persistent unexplained immobility, anorexia or cognitive change.