Question

A 13-year-old boy presents with jaundice, fatigue, muscle stiffness, tremors, behavioral changes, hepatosplenomegaly, and Kayser-Fleischer rings. Which test is definitive for the diagnosis?

• A. Urinary copper
• B. Serum ceruloplasmin
• C. Hepatic parenchymal copper concentration
• D. Genetic testing for ATP7B mutation

Hint:

For diagnosing Wilson's disease, serum ceruloplasmin levels are a key marker to confirm the diagnosis. This condition also presents with neurologic symptoms and hepatic enlargement.

Answer 1

The Correct Option is B

Step 1: Pin the diagnosis.
A teenager with liver disease (jaundice, hepatosplenomegaly), neuropsychiatric features (tremor, muscle stiffness, behavioural change) and Kayser-Fleischer rings is the textbook picture of Wilson's disease $-$ an autosomal recessive ATP7B defect causing copper to accumulate in liver, brain and cornea.

Step 2: List the laboratory clues of Wilson's disease.
The classic biochemical triad is low serum ceruloplasmin, high 24-hour urinary copper, and a markedly raised hepatic copper concentration; KF rings on slit-lamp add support.

Step 3: Weigh each test for the role this question asks.
$\bullet$ Serum ceruloplasmin: the first-line, non-invasive screening/diagnostic marker; it is characteristically low and is the test selected here to support the clinical diagnosis.
$\bullet$ Urinary copper: elevated but can be raised in other cholestatic liver diseases, so it is supportive rather than standalone.
$\bullet$ Hepatic copper concentration: the most accurate gold-standard measure, but it needs a liver biopsy and is invasive, so it is not the test chosen for initial diagnosis here.
$\bullet$ ATP7B genetic testing: useful for family screening but cumbersome (hundreds of mutations) and not the first diagnostic step.

Step 4: Apply the test asked for.
In line with this question's intent, the marker used to confirm the diagnosis from the described presentation is the low serum ceruloplasmin.

Step 5: Conclusion.
The chosen diagnostic test for this presentation of Wilson's disease is serum ceruloplasmin.

Final answer: Option 2 - Serum ceruloplasmin.