A preterm infant maintained on prolonged fat-free parenteral nutrition develops a dry, scaly, desquamating dermatosis over the trunk and limbs, poor wound healing, and a platelet count of 80,000/mm3. Plasma lipid analysis would most likely show which abnormality?

• A Elevated beta-hydroxybutyrate
• B Elevated phytanic acid
• C Elevated very long chain fatty acids
• D Elevated eicosatrienoic acid relative to arachidonic acid (raised triene to tetraene ratio) ✓

Explanation

Linoleic acid, an omega-6 essential fatty acid, cannot be synthesized by humans and must come from dietary fat. Deficiency from fat-free parenteral nutrition causes scaly dermatitis, poor growth and wound healing, and thrombocytopenia. The biochemical hallmark is a rise in the triene to tetraene ratio, meaning eicosatrienoic acid accumulates relative to arachidonic acid when linoleate is absent. Phytanic and very long chain fatty acids mark peroxisomal disorders, not dietary deficiency.

Reference: Nelson Textbook of Pediatrics, 21st ed.

High-yield for: NEET PGINI-CETNExTFMGEUSMLEPLABMRCP

Written and medically reviewed by the StethoPrep medical team.