Interpret the laboratory panel (normal complete blood count and metabolic panel, mild neutrophilia, slight unconjugated hyperbilirubinemia, and NT‑proBNP 407 pg/mL) for an adult patient.

Laboratory Interpretation: Mild Unconjugated Hyperbilirubinemia with Elevated NT-proBNP

These laboratory values show predominantly normal findings with mild unconjugated hyperbilirubinemia (total bilirubin 1.6 mg/dL with direct 0.60 mg/dL) most consistent with Gilbert syndrome in an asymptomatic patient, and an NT-proBNP of 407 pg/mL that warrants clinical correlation but does not definitively indicate heart failure. 1, 2

Complete Blood Count Analysis

• WBC 9.97, Hgb 14.9, Hct 46.6, RBC 4.95, Plt 280: All values are within normal limits with no evidence of anemia, thrombocytopenia, or leukocytosis 1
• Mild neutrophilia (65.3%, absolute 6.51): This represents a borderline elevation that is non-specific and may reflect physiologic stress, early infection, or normal variation 3, 4
• Lymphocytes 21.2%, Eosinophils 4.7%: Within acceptable ranges 3

Metabolic Panel Interpretation

• Na 141, K 4.2, Cl 101, CO2 29: Electrolytes are completely normal 1
• BUN 14, Cr 0.73, eGFR 93.71: Renal function is normal with no evidence of prerenal azotemia (BUN/Cr ratio ~19:1, which is <20:1) 1
• Glucose 99: Normal fasting glucose 1
• Ca 9.8, Protein 7.1, Albumin 4.0: Normal calcium and protein status with preserved hepatic synthetic function 5

Liver Function Tests: The Key Finding

The pattern shows mild unconjugated hyperbilirubinemia without hepatocellular injury:

• Total bilirubin 1.6 mg/dL with direct (conjugated) 0.60 mg/dL: This yields an indirect (unconjugated) bilirubin of 1.0 mg/dL, representing 62.5% of total bilirubin 5
• Since unconjugated bilirubin comprises >70% of total bilirubin, this indicates unconjugated hyperbilirubinemia 5, 1
• AST 19, ALT 16, AlkPhos 80: All aminotransferases and alkaline phosphatase are completely normal, excluding hepatocellular injury or cholestatic disease 5
• Albumin 4.0 with normal protein: Preserved hepatic synthetic function rules out significant liver disease 5

Gilbert Syndrome: The Most Likely Diagnosis

In an asymptomatic adult with isolated mild unconjugated hyperbilirubinemia (<3 mg/dL), normal aminotransferases, and normal hepatic synthetic function, Gilbert syndrome is the diagnosis 5, 1, 6:

• Gilbert syndrome affects 10-15% of the Western population and is characterized by reduced hepatic glucuronidation to approximately 30% of normal 6
• Total bilirubin typically ranges from 1.0-3.0 mg/dL (up to 80 μmol/L or ~4.7 mg/dL) with predominantly unconjugated fraction 6
• This is a benign condition requiring no treatment and no further hepatic workup if the patient is truly asymptomatic 5, 1

What to Rule Out

Before accepting Gilbert syndrome, exclude hemolysis and medication-induced hyperbilirubinemia 5, 1:

• Hemolysis markers: The normal hemoglobin (14.9), hematocrit (46.6), and MCV (94.1) argue strongly against hemolysis 1, 7
• Medication review: Obtain detailed history of all medications, supplements, and herbal products that could cause unconjugated hyperbilirubinemia 5, 2, 7
• No further imaging needed: Abdominal ultrasound is NOT indicated with isolated unconjugated hyperbilirubinemia and normal aminotransferases 5, 1

NT-proBNP Interpretation: Clinical Context is Critical

NT-proBNP 407 pg/mL falls in an intermediate zone requiring clinical correlation:

• For acute heart failure exclusion: Values <300 pg/mL effectively rule out acute HF, while values >2000 pg/mL strongly suggest acute decompensated HF 5
• This value of 407 pg/mL is mildly elevated but non-diagnostic 5
• Age matters significantly: NT-proBNP increases with age, and values >75 years can be elevated without HF 5
• Obesity lowers NT-proBNP: Obese patients may have falsely reassuring values 5

Other Causes of Elevated NT-proBNP

Multiple cardiac and non-cardiac conditions elevate NT-proBNP beyond heart failure 5:

• Cardiac causes: Acute coronary syndrome, atrial fibrillation or other arrhythmias, LV hypertrophy, valvular disease 5
• Non-cardiac causes: Renal failure (though eGFR is normal here at 93.71), pulmonary embolism, sepsis, chronic obstructive pulmonary disease 5
• With normal renal function and no other laboratory abnormalities, cardiac causes are more likely if this value is truly pathologic 5

Clinical Action for NT-proBNP

Determine if the patient has any symptoms or signs of heart failure 5:

• Symptoms to assess: Dyspnea, orthopnea, paroxysmal nocturnal dyspnea, fatigue, exercise intolerance 5
• Physical examination findings: Peripheral edema, elevated jugular venous pressure, pulmonary rales, S3 gallop, hepatojugular reflux 5
• If asymptomatic with no physical findings: NT-proBNP of 407 pg/mL may represent chronic elevation from LV hypertrophy, diastolic dysfunction, or atrial arrhythmia rather than acute HF 5
• If symptomatic: Obtain echocardiogram and chest X-ray to evaluate for structural heart disease and pulmonary congestion 5

Recommended Clinical Approach

For the mild unconjugated hyperbilirubinemia:

1. Confirm patient is truly asymptomatic: No jaundice, right upper quadrant pain, pruritus, dark urine, pale stools, or constitutional symptoms 5, 1
2. Review all medications and supplements: Exclude drug-induced hyperbilirubinemia 5, 2, 7
3. If asymptomatic with negative medication review: Diagnose Gilbert syndrome and reassure patient this is benign 5, 1, 6
4. No repeat testing needed unless bilirubin rises significantly or symptoms develop 5, 1

For the NT-proBNP elevation:

1. Obtain focused cardiovascular history: Assess for dyspnea, chest pain, palpitations, exercise tolerance, orthopnea 5
2. Perform cardiovascular physical examination: Check for edema, JVP, pulmonary rales, S3 gallop, irregular rhythm 5
3. If symptomatic or abnormal examination: Order echocardiogram and consider chest X-ray 5
4. If asymptomatic with normal examination: Consider echocardiogram to evaluate for structural heart disease (LV hypertrophy, diastolic dysfunction, valvular disease) or repeat NT-proBNP when clinically indicated 5
5. Check for atrial fibrillation: Obtain ECG as atrial arrhythmias commonly elevate NT-proBNP 5

Common Pitfalls to Avoid

• Do not order abdominal ultrasound for isolated unconjugated hyperbilirubinemia with normal aminotransferases: This represents unnecessary testing and cost 5, 1
• Do not assume NT-proBNP 407 pg/mL equals heart failure: This value requires clinical correlation and is non-diagnostic in isolation 5
• Do not repeat bilirubin "to see if it normalizes" in Gilbert syndrome: The diagnosis is made by the pattern, not by normalization 5, 1
• Do not overlook medications as a cause of unconjugated hyperbilirubinemia: Many drugs can interfere with bilirubin conjugation 5, 2, 7
• Do not ignore the clinical context for NT-proBNP: Age, obesity, renal function, and acute versus chronic symptoms dramatically affect interpretation 5