Copper transport — After intestinal absorption, which carrier predominantly transports copper from enterocytes to the liver in portal blood?

Introduction / Context:Copper absorbed in the small intestine must be trafficked to the liver, where it is incorporated into cuproenzymes and into ceruloplasmin for systemic delivery. Understanding which plasma proteins carry copper at each stage clarifies laboratory findings and disease mechanisms in copper disorders.

Given Data / Assumptions:

• Immediately post-absorption, copper appears in portal blood bound primarily to albumin (and to a lesser extent transcuprein/alpha-2-macroglobulin).
• Ceruloplasmin is synthesized by the liver and then carries copper systemically.
• Transferrin is the iron transport protein and does not normally carry copper.

Concept / Approach:Distinguish early transport from systemic distribution. The question asks specifically about transport from intestinal cells to the liver, which points to albumin-bound copper rather than ceruloplasmin (a hepatic product for peripheral delivery).

Step-by-Step Solution:

Verification / Alternative check:Clinical chemistry shows low ceruloplasmin in Wilson’s disease despite copper overload; newly absorbed copper is not ceruloplasmin-bound until processed by the liver.

Why Other Options Are Wrong:

Common Pitfalls:Assuming “ceruloplasmin” for any copper transport question; remember the sequence: albumin in portal blood → liver → ceruloplasmin to tissues.

Final Answer:Albumin.