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Zorluk: OrtaInterpreting Laboratory Results

A 56-year-old man is brought to the emergency department by his daughter due to increasing confusion and abdominal swelling over the past 3 days. He has a history of alcohol use disorder. His temperature is 37.9°C (100.2°F), blood pressure is 105/65 mm Hg, and pulse is 98/min. Physical examination reveals scleral icterus, spider angiomas on the chest, a distended abdomen with a positive fluid wave, and bilateral pitting pedal edema. When the patient extends his arms and dorsiflexes his wrists, a flapping tremor is observed.

Laboratory studies show:

TestResultReference Range
Serum sodium132 mEq/L136-145 mEq/L
Serum creatinine1.4 mg/dL0.7-1.3 mg/dL
Serum albumin2.7 g/dL3.5-5.0 g/dL
Total bilirubin3.8 mg/dL0.1-1.2 mg/dL
Aspartate aminotransferase (AST)145 U/L10-40 U/L
Alanine aminotransferase (ALT)62 U/L7-56 U/L
Serum lactate dehydrogenase (LDH)300 U/L100-250 U/L
Serum glucose95 mg/dL70-99 mg/dL

A diagnostic paracentesis is performed, yielding cloudy yellow fluid. Ascitic fluid analysis reveals:

TestResult
Total protein0.9 g/dL
Albumin1.1 g/dL
Lactate dehydrogenase (LDH)110 U/L
Glucose85 mg/dL
White blood cell count400/mm³
Neutrophils75%
Lymphocytes25%
Red blood cell count100/mm³

Based on these laboratory results, which of the following is the most accurate diagnostic interpretation?

  1. Spontaneous bacterial peritonitisCevap
  2. B
    Uncomplicated cirrhotic ascites
  3. C
    Secondary bacterial peritonitis
  4. D
    Ascites secondary to right-sided heart failure
  5. E
    Malignant peritoneal carcinomatosis

Cevap

Spontaneous bacterial peritonitis
The correct answer is spontaneous bacterial peritonitis (SBP). The patient's presentation with altered mental status (hepatic encephalopathy), fever, and abdominal pain raises high suspicion for an infection. Ascitic fluid analysis demonstrates a Serum-Ascites Albumin Gradient (SAAG) of 1.6 g/dL, which is ≥1.1\geq 1.1 g/dL, confirming underlying portal hypertension. Crucially, the absolute neutrophil count (ANC) must be calculated: 400/mm3×0.75=300/mm3400/\text{mm}^3 \times 0.75 = 300/\text{mm}^3. An ANC ≥250/mm3\geq 250/\text{mm}^3 is the diagnostic hallmark of SBP.

Adım Adım Çözüm

1
Calculate the Serum-Ascites Albumin Gradient (SAAG).
SAAG = Serum Albumin - Ascitic Albumin = 2.7−1.1=1.62.7 - 1.1 = 1.6 g/dL.
A SAAG ≥1.1\geq 1.1 g/dL indicates that portal hypertension is the underlying cause of the ascites.
2
Calculate the absolute neutrophil count (ANC) of the ascitic fluid.
ANC = Total WBC ×\times Neutrophil percentage = 400×0.75=300/mm3400 \times 0.75 = 300/\text{mm}^3.
An ANC ≥250/mm3\geq 250/\text{mm}^3 establishes the diagnosis of spontaneous bacterial peritonitis.
3
Evaluate criteria for secondary bacterial peritonitis.
Ascitic protein is <1.0< 1.0 g/dL, glucose is >50> 50 mg/dL, and ascitic LDH is less than the upper limit of normal for serum LDH.
Runyon's criteria for secondary bacterial peritonitis are not met, confirming spontaneous bacterial peritonitis as the diagnosis.

Anahtar Kavram

Interpretation of ascitic fluid analysis requires calculating the SAAG to identify portal hypertension and the absolute neutrophil count to diagnose spontaneous bacterial peritonitis.
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