Can elderly patients have positive leukocytes (white blood cells) even if they are asymptomatic?

Leukocytosis in Asymptomatic Elderly Patients

Yes, elderly patients commonly have positive leukocytes (elevated white blood cell counts) even when they are asymptomatic, particularly in the context of urinary tract colonization. 1

Prevalence and Significance of Asymptomatic Leukocytosis in the Elderly

Urinary Tract

• In elderly residents of long-term care facilities, asymptomatic bacteriuria with associated pyuria (≥10 WBCs/high-power field) is extremely common 1
• For residents with chronic indwelling urinary catheters, the presence of bacteriuria and pyuria is virtually universal 1
• Prospective studies have shown that untreated asymptomatic bacteriuria in elderly patients without long-term indwelling urinary catheters can persist for 1-2 years without evidence of increased morbidity or mortality 1

Systemic Leukocytosis

• Elderly patients often have elevated but normal leukocyte counts that may reflect increased systemic inflammation rather than acute infection 2
• These elevated counts within normal range (particularly neutrophils and monocytes) may be a harbinger of subclinical disease 2
• In a study of hospitalized geriatric patients, white blood cell count (WBCC) was not significantly different between infected and non-infected patients, making it an unreliable biomarker for infection in this population 3

Factors Contributing to Leukocytosis in the Elderly

Several factors can contribute to elevated white blood cell counts in elderly patients even without active infection:

• Chronic inflammatory conditions common in elderly patients 4
• Cardiovascular disease and risk factors 3
• Stress response (including emotional stress, trauma, and surgery) 5
• Medications (corticosteroids, lithium, beta-agonists) 5
• Smoking and obesity 5
• Age-related changes in immune function 2

Clinical Implications and Recommendations

For Urinary Tract Assessment

1. Urinalysis and urine cultures should not be performed for asymptomatic elderly patients (A-I) 1
2. Diagnostic evaluation for UTI should be reserved for those with acute onset of UTI-associated symptoms (fever, dysuria, gross hematuria, new/worsening urinary incontinence, suspected bacteremia) (A-II) 1
3. The minimum laboratory evaluation for suspected UTI should include:
   • Urinalysis for leukocyte esterase and nitrite level by dipstick
   • Microscopic examination for WBCs (B-II) 1
4. Only if pyuria (≥10 WBCs/high-power field) or positive leukocyte esterase or nitrite test is present should a urine culture be ordered (B-III) 1

For Systemic Assessment

1. Left shift in white blood cell count (increased percentage of immature neutrophils/bands) strongly indicates active bacterial infection, even in the absence of fever 4
2. The combination of left shift and elevated WBC count (>14,000 cells/mm³) provides stronger evidence of bacterial infection than either finding alone 4
3. Clinical signs and symptoms should guide diagnosis, not laboratory values alone 4

Pitfalls to Avoid

1. Overdiagnosis: Treating asymptomatic bacteriuria or leukocytosis in elderly patients can lead to unnecessary antibiotic use, contributing to antimicrobial resistance and adverse effects 4

2. Misinterpretation: Positive reagent strip testing is an unreliable method of identifying elderly patients with true urinary tract infections 6

3. Underdiagnosis: Elderly patients may present with atypical symptoms of infection, and the absence of leukocytosis does not rule out infection 4

4. Inappropriate testing: Ordering urine cultures for asymptomatic elderly patients leads to detection of asymptomatic bacteriuria, which should not be treated 1

In conclusion, leukocytosis in elderly patients must be interpreted in the clinical context rather than as an isolated finding. The presence of elevated white blood cells in asymptomatic elderly patients is common and often does not indicate active infection requiring treatment.