Question

Choose the best method of diagnosis for the clinical sign represented in the image.

• A. Serum copper
• B. Serum ceruloplasmin
• C. Karyotyping
• D. PCR

Hint:

A golden-brown corneal ring points to Wilson's disease - test the copper-carrying protein.

Answer 1

The Correct Option is B

Step 1: The image shows a Kayser-Fleischer (KF) ring, a golden-brown ring at the corneal periphery caused by deposition of copper in Descemet's membrane. This sign is the hallmark of Wilson's disease, an autosomal recessive disorder of abnormal copper metabolism.
Step 2: In Wilson's disease, defective copper transport leads to reduced incorporation of copper into ceruloplasmin. Therefore serum ceruloplasmin (a copper-containing ferroxidase) is characteristically decreased and is a key part of Sternlieb's diagnostic criteria, along with KF rings, raised hepatic copper, and increased 24-hour urinary copper.
Step 3: Among the options, serum ceruloplasmin is the best single biochemical test offered for confirming the disease behind this sign.
Step 4: Why not the others - total serum copper is often low or misleadingly normal because protein-bound copper falls while free copper rises, so it is a poor screening test. Karyotyping detects chromosomal disorders, not a copper metabolism defect. PCR/genetic testing for ATP7B is confirmatory in difficult cases but is not the best first-line method listed here. Hence serum ceruloplasmin is correct.