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Causes??
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Finding Sources
Finding Sources
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Reading File
Here is a full breakdown based on the CBC findings and what the textbooks say:
CBC Summary - Key Abnormalities
| Finding | Value | Status |
|---|---|---|
| Total WBC | 11,750 cells/cumm | HIGH (ref: 4,000-10,000) |
| Absolute Neutrophil Count (ANC) | 8,578 cells/cumm | HIGH (ref: 2,000-7,000) |
| Lymphocytes % | 18.3% | LOW (ref: 20-40%) |
| Hb, MCV, MCH, Platelets | All normal | Normal |
The primary finding is leukocytosis driven by neutrophilia (a neutrophilic leukocytosis). The red cell picture is completely normal (normocytic/normochromic), and no atypical/blast cells are seen.
Causes of Neutrophilic Leukocytosis
1. Infections (Most Common)
- Bacterial infections - acute bacterial infections are the #1 cause (pneumonia, UTI, skin/soft tissue, abscess, sepsis)
- Fungal infections
- Some parasitic infections
- Note: viral infections more commonly cause lymphocytosis or normal WBC, but some (e.g., early COVID-19) can cause neutrophilia
2. Physiological / Stress Response
- Physical or emotional stress causes catecholamine release, which demarginalizes neutrophils from vessel walls into circulation within minutes
- Post-exercise
- Post-surgery or trauma
- Burns
3. Drugs
- Corticosteroids - the most well-known cause; they reduce neutrophil egress from circulation
- Beta-agonists (e.g., salbutamol/albuterol)
- Lithium - increases endogenous colony-stimulating factors (CSFs)
- G-CSF / GM-CSF therapy
4. Inflammatory / Autoimmune Disorders
- Rheumatoid arthritis, vasculitis, inflammatory bowel disease
- Tissue necrosis (e.g., acute myocardial infarction - elevated WBC is a recognized finding and correlates with worse prognosis)
5. Metabolic / Endocrine
- Diabetic ketoacidosis (DKA)
- Gout (acute attack)
- Thyroid storm
- Uremia
6. Cigarette Smoking
- Chronic smokers have neutrophilia in ~25-50% of cases, thought to be due to slowed neutrophil apoptosis from cigarette smoke. It can persist up to 5 years after cessation.
7. Malignancy
- Some solid tumors (lung, head/neck, kidney, bladder) can secrete G-CSF ectopically, causing leukocytosis
- Myeloproliferative neoplasms (e.g., CML) - however, in CML the WBC is typically dramatically elevated (>50,000-100,000) with left shift; this CBC does NOT fit CML
- Leukoerythroblastic reaction from bone marrow metastases
8. Hematologic Causes
- Hemolytic anemia, ITP (marrow stimulation causing reactive neutrophilia)
- Post-splenectomy
What This CBC Most Likely Represents
Given the mild leukocytosis (11,750 - only modestly elevated), neutrophilia without left shift (no bands/blasts mentioned, no atypical cells = 0%), and normal red cell and platelet indices, this picture is most consistent with:
- Acute bacterial infection (most likely) - look for fever, localizing symptoms (cough, dysuria, cellulitis, abdominal pain)
- Physiological/stress-related neutrophilia - a common benign finding
- Corticosteroid or other drug use
- Smoker's leukocytosis
The level of WBC elevation (~11,750) is mild, and the absence of any blast or atypical cells makes a primary hematologic malignancy very unlikely. If infection is suspected, clinical correlation and possibly CRP/ESR and cultures would be the next step.
- Textbook of Family Medicine 9e, Table 14-10 - Common Causes of Leukocytosis
- Goldman-Cecil Medicine - Drug-Induced and Stress Leukocytosis sections
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