[The diagnostic value and limits of diagnostic parameters for Wilson's disease].Zhonghua Gan Zang Bing Za Zhi. 2017 Dec 20; 25(12):881-885.ZG
Wilson disease (WD) is a rare and treatable genetic disorder. This paper describes the new advances and author's long-term experiences in the diagnosis of WD. The characteristics in clinical and routine tests are: the age of presentation can be quite broad, the WD could not be excluded based on age only; the patients usually have mild digestive symptoms but obvious chronic liver disease signs; liver function tests may reveal normal or a mild elevation in bilirubin, ALT and AST, but quite abnormal in serum albumin and prothrombin time in most patients; Coombs-negative hemolytic anemia, normal or markedly subnormal serum alkaline phosphatase (typically < 40 IU/L) are useful for the diagnosis of fulminant WD. In china, Kayser-Fleischer rings are present in 72.2% of patients at the time of diagnosis, the positive rate is significantly higher in patients with a neurological presentation (93.4%) than patients presenting with liver disease (63.3%), however, they are usually absent in children under 6 years old, occasionly present in patients with chronic cholestatic liver disease. The mean serum ceruloplamin level in WD patients is 71.1 ± 48.7 mg/L, the level is < 200 mg/L in 98.9% of patients, < 100 mg/L in about three fourths patients, < 50 mg/L in about half patients, but it may be low in 50% of patients with severe end-stage liver disease of any etiology too, and even lower than 50 mg/L in patients with nephritic syndrome. Basal 24-hour urinary copper excretion may be≥100 g at presentation in 86.7% of patients with WD, but also in 22% of Patients with certain chronic liver diseases, the sensitivity of penicillamine challenge test is lower than basal urinary copper excretion, however, the specificity is significantly higher than former (97% versus 78%). Hepatic copper determination remains the gold standard for the diagnosis of WD. We have designed a standard method for hepatic copper determination. The most useful cut-off value is 209 g/g dry wt using our method, with the sensitivity of 99.4%, and specificity of 96.1%. However, long-standing hepatic failure and or obstruction can cause heptic copper elevations into the WD area. In recent years, direct complete DNA sequencing has become easy, rapid, less expensive and commercially available. Currently reported mutation detection rate is 90%, the specificity is almost 100%. The limitation to the method has been the ability to identify all the affected alleles in suspected individuals. If no mutation is identified, the diagnosis of WD could not be excluded. None of the laboratory parameters alone allows a definite diagnosis of WD. The WD diagnostic scoring system based on a composite of key parameters helps clinicians to gauge the degree of certainty of the diagnosis: WD scores greater than 4, the diagnosis of WD is highly likely; score 0 or 1, the diagnosis is unlikely. However, the WD diagnosis could not be excluded in suspected patients who do not perform genetic test and hepatic copper determination. Patients with chronic cholestatic liver disease may have scores more than 4.