Diabetic Ketoacidosis with Possible Underlying Infection
This patient has diabetic ketoacidosis (DKA) with a left shift suggesting bacterial infection, requiring immediate IV insulin, aggressive fluid resuscitation, electrolyte replacement, and empiric broad-spectrum antibiotics after obtaining cultures.
Immediate Life-Threatening Diagnosis: Diabetic Ketoacidosis
The combination of hyperglycemia (245 mg/dL), elevated anion gap (25 mEq/L), and low chloride definitively indicates DKA 1. This is a medical emergency requiring immediate intervention before addressing the leukocytosis 1, 2.
Priority management steps for DKA:
- Start IV insulin infusion immediately 1
- Aggressive IV fluid resuscitation with normal saline 1
- Correct electrolyte abnormalities, particularly potassium and phosphate 1
- Monitor glucose hourly and anion gap every 2-4 hours 1
Secondary Urgent Issue: Left Shift Indicating Bacterial Infection
The WBC of 12.9 × 10⁹/L with 82.1% neutrophils and 1.1% myelocytes represents a significant left shift 1, 3. An absolute band count ≥1,500 cells/mm³ has a likelihood ratio of 14.5 for documented bacterial infection, and band percentage ≥16% has a likelihood ratio of 4.7 1, 3. The presence of myelocytes (1.1%) further confirms a left shift, indicating bone marrow response to infection 4, 5.
Critical point: Left shift can occur even with only mildly elevated total WBC count and still indicates significant bacterial infection requiring evaluation 1, 3. Do not ignore this finding simply because the WBC is only 12.9 3, 6.
Infection Workup Required Before Antibiotics
Obtain these studies immediately:
- Blood cultures (two sets from separate sites) before antibiotics 3
- Urinalysis with microscopy and urine culture if pyuria present 3
- Chest X-ray to evaluate for pneumonia 3
- Assess for skin/soft tissue infection, particularly diabetic foot ulcers 3
Do not obtain urinalysis if truly asymptomatic for urinary symptoms, as asymptomatic bacteriuria occurs in 15-50% of elderly patients and does not require treatment 3, 6. However, query specifically for dysuria, flank pain, increased frequency, or new incontinence 3.
Empiric Antibiotic Initiation
Start broad-spectrum empiric antibiotics immediately after obtaining cultures based on suspected infection source and local resistance patterns 3. The left shift combined with DKA suggests a serious bacterial infection that may have precipitated the metabolic decompensation 1, 3.
Common infection sources precipitating DKA include:
- Urinary tract infection (most common) 1, 7
- Pneumonia 1, 7
- Skin/soft tissue infection 1, 7
- Intra-abdominal infection 1
Additional Laboratory Considerations
The lymphopenia (2.1%) is consistent with acute bacterial infection and physiologic stress 1, 7. The platelet count of 405 × 10⁹/L represents reactive thrombocytosis, commonly seen with infection and inflammation 1.
The TSH of 0.197 suggests possible hyperthyroidism, which can precipitate DKA and should be addressed after stabilization 1. Elevated triglycerides (445 mg/dL) are expected in DKA due to insulin deficiency 1.
Critical Pitfalls to Avoid
- Do not delay insulin therapy to complete the infection workup—DKA takes priority 1
- Do not rely on automated differential alone—manual differential is essential to accurately assess band forms 1, 3, 6
- Do not ignore left shift when total WBC is only mildly elevated—this combination still indicates significant bacterial infection 1, 3
- Do not treat asymptomatic bacteriuria in elderly patients, but do treat symptomatic UTI aggressively 3, 6
- Do not assume absence of infection based on lack of fever—elderly patients and those with DKA may not mount a febrile response 3, 6
Monitoring During Treatment
- Glucose and electrolytes every 1-2 hours initially 1
- Anion gap every 2-4 hours until closure 1
- Repeat CBC with manual differential in 12-24 hours to assess response to antibiotics 1, 3
- Vital signs every 1-2 hours, watching for sepsis (temperature >38°C or <36°C, systolic BP <90 mmHg, heart rate >100 bpm, respiratory rate >20/min) 3