What should I check when an elderly patient complains of weakness?

Evaluation of Weakness in Elderly Patients

When an elderly patient complains of weakness, immediately assess vital signs (heart rate >90 bpm, systolic BP <110 mmHg warrant urgent evaluation), obtain blood glucose and hemoglobin A1c, check electrolytes (particularly potassium, phosphate, magnesium), perform a complete blood count, and conduct a comprehensive medication review focusing on diuretics, psychotropics, and anticoagulants. 1, 2, 3

Immediate Vital Signs and Risk Stratification

• Check heart rate and blood pressure immediately - elderly patients require lower thresholds for concern, with heart rate >90 bpm and systolic blood pressure <110 mmHg indicating potential hemodynamic instability requiring urgent intervention 1
• Obtain orthostatic blood pressure measurements - standing from supine position to detect volume depletion or autonomic dysfunction 1, 2
• Perform blood gas analysis (arterial or venous) for baseline lactate and base deficit assessment, as these are markers of occult hypoperfusion in elderly patients 1

Essential Laboratory Workup

First-Tier Tests (Obtain Immediately)

• Blood glucose and hemoglobin A1c - diabetes is a common cause of weakness through neuropathy and metabolic derangement 1, 3
• Complete blood count with differential - to evaluate for anemia, infection, or pancytopenia 2
• Electrolytes including potassium, phosphate, and magnesium - diuretics commonly cause hypokalemia and azotemia leading to weakness 2, 3
• Renal function (BUN/creatinine) - azotemia from diuretics or dehydration is a frequent culprit 3
• Thyroid-stimulating hormone (TSH) - hypothyroidism presents with weakness and is easily treatable 4

Critical Refeeding Syndrome Monitoring

• If the patient appears malnourished (unintentional weight loss >10%, BMI <20 if <70 years or <22 if >70 years), immediately check phosphate, magnesium, potassium, and thiamine levels before any nutritional intervention 1, 2
• Monitor these electrolytes daily for the first 72 hours if nutritional support is initiated - refeeding syndrome carries up to 20% mortality risk 1, 2

Comprehensive Medication Review

• Review ALL medications for myelotoxic agents including azathioprine, anticoagulants, antibiotics, and antihypertensives 2
• Identify sedating medications - psychotropics impair emotional and physical drive and are major fall risk factors 1, 3
• Assess for polypharmacy and drug-drug interactions - elderly patients on multiple medications are at high risk for adverse effects 1
• Check for medications causing hypoglycemia in diabetic patients - overtreatment is common and dangerous in the elderly 1

Focused History Elements

Clarify the Nature of "Weakness"

• Distinguish true muscle weakness from fatigue, asthenia, or functional decline - these are separate conditions requiring different evaluations 5, 4
• Determine pattern: generalized versus focal, proximal versus distal, acute versus chronic 4

Red Flag Symptoms Requiring Urgent Neuroimaging

• New focal neurological deficits, altered mental status, or sudden deterioration - obtain brain and spinal cord MRI emergently to exclude stroke, hemorrhage, or spinal cord compression 6
• Headache with scalp tenderness or jaw claudication - immediately check erythrocyte sedimentation rate and C-reactive protein for giant cell arteritis 1

Geriatric Syndrome Assessment

• Screen for falls in the past 12 months - falls are frequently unreported and indicate multiple risk factors including medications, balance disorders, and visual deficits 1
• Assess for urinary incontinence - new incontinence warrants evaluation for UTI (occurs in 15-60% of neurological patients), urinary retention, or neurological injury 1, 6
• Evaluate cognitive function using standardized screening (Montreal Cognitive Assessment) - cognitive impairment affects self-care ability and medication management 1
• Document unintentional weight loss - >5% over 3 months combined with low BMI indicates malnutrition risk 1

Specific Symptom Inquiry

• Difficulty with gait and balance - indicates fall risk and potential neurological or musculoskeletal pathology 1
• Time spent on floor after falls - prolonged immobility suggests severe weakness or inability to call for help 1
• Pain assessment - chronic pain is a common geriatric syndrome affecting function 1
• Peripheral neuropathy symptoms - diabetes and alcoholism are common causes in elderly 3

Physical Examination Priorities

• Objective strength testing - document specific muscle groups affected and severity 4
• Neurological survey - assess for patterns suggesting central versus peripheral nervous system involvement 4
• Gait assessment and "Get Up and Go" test - patients unable to rise from bed, turn, and steadily ambulate require reassessment before discharge 1
• Visual examination - visual deficits contribute to falls and functional impairment 1
• Fundoscopic examination - look for papilledema indicating elevated intracranial pressure 1

Frailty Assessment

• Assess frailty in ALL elderly trauma or acutely ill patients using Clinical Frailty Score (1=very fit to 7=very frail) 1
• Evaluate functional status - activities of daily living and instrumental activities of daily living capacity 1
• Consider Geriatric Trauma Outcome Score even in non-trauma presentations to predict poor outcomes 1

Additional Testing Based on Clinical Suspicion

If Infection Suspected

• Urinalysis and urine culture immediately - UTI is extremely common and causes acute mental status changes and weakness 1, 6
• Blood cultures if febrile 1

If Inflammatory/Rheumatologic Cause Suspected

• Erythrocyte sedimentation rate and C-reactive protein 1, 4
• Antinuclear antibody assay 4

If Myopathy Suspected

• Creatine kinase level 4
• Consider electromyography if diagnosis remains unclear after initial workup 4

If Neurological Cause Suspected

• Brain and spinal cord MRI with and without contrast - particularly if no vasculopathic risk factors or if symptoms fail to improve in 4-6 weeks 1, 6

Critical Pitfalls to Avoid

• Never assume symptoms are "just old age" - elderly patients deserve the same thorough evaluation as younger patients, with lower thresholds for intervention 1
• Do not delay imaging in patients with new neurological symptoms - acute stroke and spinal pathology require time-sensitive intervention 6
• Avoid aggressive nutritional support without refeeding syndrome monitoring - start low and go slow, with daily electrolyte monitoring for 72 hours 1, 2
• Do not continue potentially harmful medications without clear indication - deintensification is often appropriate in elderly patients 1, 2
• Never discharge patients who cannot safely ambulate without ensuring adequate support and follow-up 1