The clinical utility of a low serum ceruloplasmin measurement in the diagnosis of Wilson Disease

The first step in screening for potential Wilson disease is serum ceruloplasmin testing, whereby a level of less than 0.2g/L is suggestive of the disease. We aimed to determine what proportion of an Irish population had a low ceruloplasmin level, whether low measurements were appropriately followed-up and what were the clinical outcomes. We conducted a retrospective review of all serum ceruloplasmin measurements between August 2003 and October 2009 in a large tertiary referral centre in Southern Ireland. Clinical data, serum ceruloplasmin, liver function tests, urinary copper and liver biopsy reports were all recorded where available. 1573 patients had a serum ceruloplasmin measurement during the 7-year study period. 96 patients (6.1%) had a ceruloplasmin level < 0.2g/L and of these only 3 patients had Wilson disease. There was only 1 new diagnosis. Only 27 patients (28.1%) had some form of confirmatory testing performed. In our centre's experience, the positive predictive value of a significantly low ceruloplasmin level is 11.1% (95% CI 2.91-30.3%). In practice a low serum ceruloplasmin measurement is often not followed by appropriate confirmatory testing. Measuring serum ceruloplasmin as a singular diagnostic test for Wilson disease or as part of the battery of unselected liver screening tests is inappropriate and low-yield.