[Abnormal Serum Total Protein Measurement by Lipoprotein-X in an Infant with Biliary Atresia]

Area of Science:

• Clinical Chemistry
• Biochemistry
• Pediatric Gastroenterology

Background:

• Cholestatic jaundice, often seen in infants with biliary atresia, is known to cause assay interference for low-density lipoprotein-cholesterol.
• The impact of Lipoprotein-X (LP-X) on other biochemical assays, particularly total serum protein, remains largely uncharacterized.

Observation:

• A case report details an 11-month-old infant diagnosed with biliary atresia presenting with jaundice since two months of age.
• Biochemical testing revealed markedly elevated total serum protein levels when measured by the biuret method, exhibiting abnormal response curves and dilution linearity.
• Agar electrophoresis confirmed the presence of Lipoprotein-X (LP-X) in the patient's serum.

Findings:

• Experiments involving ultracentrifugation and fractionation of the patient's LP-X-rich lipoprotein fraction demonstrated abnormal reactions with the biuret method.
• Specifically, normal gamma-globulin fractions showed aberrant results when incubated with the patient's LP-X-rich lipoproteins.
• These findings indicate that LP-X significantly influences total serum protein measurements performed using the biuret method in infants with biliary atresia.

Implications:

• The study highlights a critical analytical interference in total serum protein assays caused by LP-X in cholestatic infants.
• This interference may lead to inaccurate clinical interpretations and requires careful consideration in the biochemical assessment of pediatric cholestatic conditions.
• Further research is warranted to elucidate the precise mechanism of LP-X interaction with the biuret assay and to develop methods for accurate protein quantification in such cases.