A patient maintained on fat-free total parenteral nutrition for five weeks develops a desquamating scaly rash, alopecia, and thrombocytopenia. The most likely deficiency, and the fatty acid whose absence causes it, are:

• A Vitamin A deficiency due to lack of retinol esters
• B Essential fatty acid deficiency due to lack of linoleic acid ✓
• C Zinc deficiency due to lack of divalent cations
• D Vitamin E deficiency due to lack of tocopherol

Explanation

Linoleic acid cannot be synthesised by humans and must come from lipid emulsion in parenteral feeds. Deficiency appears after roughly four to six weeks of fat-free PN and classically causes a scaly desquamating dermatitis, alopecia, thrombocytopenia, and poor wound healing, with a raised triene-to-tetraene ratio diagnostically. Zinc deficiency also causes dermatitis but typically a periorificial acrodermatitis with diarrhoea, not thrombocytopenia.

Reference: Schwartz's Principles of Surgery, 11th ed.

High-yield for: NEET PGINI-CETNExTFMGEUSMLEPLABMRCP

Written and medically reviewed by the StethoPrep medical team.