What is the appropriate workup for a 76-year-old patient presenting to the emergency room with a 2-day history of vomiting and diarrhea?

Workup of a 76-Year-Old with Vomiting and Diarrhea in the Emergency Department

Immediately assess hydration status using specific clinical signs: check for at least four of the following seven indicators—confusion, non-fluent speech, extremity weakness, dry mucous membranes, dry tongue, furrowed tongue, and sunken eyes—as the presence of four or more indicates moderate to severe volume depletion requiring aggressive fluid resuscitation. 1

Initial Assessment and Severity Stratification

Clinical Evaluation

• Document specific diarrhea characteristics: number of stools above baseline, stool composition (watery vs. bloody), presence of nocturnal diarrhea 1
• Assess for "complicated" features that mandate aggressive management:
  • Fever (suggests infectious complications or sepsis) 1
  • Orthostatic dizziness or postural pulse change >30 beats/minute (indicates significant volume depletion) 1
  • Moderate to severe abdominal cramping (harbinger of severe diarrhea) 1
  • Altered mental status 1
  • Signs of shock or severe dehydration 1

Volume Depletion Assessment in Elderly Patients

The 76-year-old patient requires age-specific assessment criteria. Check the seven-sign assessment for volume depletion: confusion, non-fluent speech, extremity weakness, dry mucous membranes, dry tongue, furrowed tongue, and sunken eyes—four or more positive signs indicate moderate to severe depletion. 1 Note that traditional signs like skin turgor may be unreliable in elderly patients.

Laboratory Workup

Essential Initial Testing

• Complete blood count to assess for infection, anemia from bleeding 1
• Comprehensive metabolic panel including electrolytes (sodium, potassium, chloride, bicarbonate), renal function (BUN, creatinine) 1, 2
• Blood cultures if febrile 1

Stool Studies (When Indicated)

Empiric antimicrobial therapy is NOT recommended for most acute watery diarrhea without recent international travel in immunocompetent adults. 1 However, obtain stool workup if the patient has:

• Fever, bloody stools, or severe symptoms: Test for fecal leukocytes, Clostridioides difficile, Salmonella, E. coli, Campylobacter, and infectious colitis 1
• Immunocompromised status or ill-appearing presentation: These patients may warrant empiric treatment even before results return 1

Fluid Resuscitation Strategy

Mild to Moderate Dehydration

Initiate oral rehydration solution (ORS) as first-line therapy for mild to moderate dehydration—this is strongly recommended over intravenous fluids when the patient can tolerate oral intake. 1 ORS should be continued until clinical dehydration is corrected. 1

Severe Dehydration or Inability to Tolerate Oral Intake

Administer isotonic intravenous fluids (lactated Ringer's or normal saline) immediately if the patient has:

• Severe dehydration with shock 1
• Altered mental status 1
• Persistent vomiting preventing oral intake 1
• Ileus 1

Continue IV rehydration until pulse, perfusion, and mental status normalize, then transition to ORS for remaining deficit replacement. 1 In elderly patients, isotonic fluids can be administered orally, nasogastrically, subcutaneously, or intravenously depending on severity. 1

Symptomatic Management

Antiemetic Therapy

Consider ondansetron to facilitate oral rehydration tolerance once adequate hydration is initiated—but antiemetics are not a substitute for fluid therapy. 1

Antimotility Agents

Loperamide may be given to immunocompetent adults with acute watery diarrhea (initial dose 4 mg, then 2 mg every 4 hours or after each unformed stool, maximum 16 mg/day), but AVOID if the patient has fever or bloody diarrhea due to risk of toxic megacolon. 1 In this 76-year-old, only use loperamide after adequate hydration and if there are no signs of inflammatory diarrhea. 1

Disposition and Monitoring

Criteria for Hospitalization

Admit the patient if any of the following are present:

• Severe dehydration requiring IV fluids 1
• Persistent vomiting preventing oral rehydration 3
• Altered mental status or shock 1
• Fever with suspected sepsis 1
• Significant electrolyte abnormalities requiring IV correction 2

Outpatient Management (If Appropriate)

If the patient has mild to moderate dehydration without complicating features:

• Prescribe ORS for home use with clear instructions to drink 8-10 large glasses of clear liquids daily 1
• Dietary modifications: eliminate lactose-containing products, alcohol, and high-osmolar supplements; recommend BRAT diet (bananas, rice, applesauce, toast) 1
• Close follow-up within 24-48 hours to reassess hydration status and symptom progression

Critical Pitfalls to Avoid

• Do not assume "dehydration" without distinguishing between true dehydration (hypernatremia with intracellular water loss) and volume depletion (extracellular fluid loss) 4—this 76-year-old likely has volume depletion from GI losses requiring isotonic fluid replacement
• Do not give loperamide if fever or bloody stools are present due to risk of toxic megacolon 1
• Do not correct severe hypernatremia or hyponatremia too rapidly as this can cause neurological damage or death 4—correct electrolyte abnormalities gradually based on laboratory monitoring
• Do not withhold empiric antibiotics in elderly patients who appear septic or have high fever with bloody diarrhea while awaiting stool culture results 1