Specimen collection and handling:
(1) The liver biopsy must be collected with copper-free needles.
(2) The biopsy must be handled and transported in copper-free containers and fixative.
(3) Analysis should only be performed by a laboratory familiar with the technique.
Analysis:
(1) weight of the liver biopsy after drying, in grams
(2) amount of copper in the biopsy as µmol or µg
1 mol copper = 63.546 g
1 µg copper = 0.01574 µmol
weight of copper per g dried liver weight =
= (µmol copper in sample) / (weight of sample in grams)
Interpretation:
• The normal range for hepatic copper at the Mayo Clinic is 0.16 to 0.55 µmol per g dry weight liver (10 to 36 µg per g dry weight liver).
• A patient with homozygous Wilson disease will have an elevated copper level, often >= 250 µg per g liver dried (>= 3.94 µmol). This is 6.94 times the upper limit of the normal reference range.
• The presence of copper levels in the normal range excludes Wilson's disease.
• A patient heterozygous for Wilson's disease may have a normal liver level or one that is elevated. However, the level does not reach that seen with homozygous disease.
• A patient with primary biliary cirrhosis or a cholestatic syndrome may have an elevated copper level, but this will not reach the level seen in patient's with homozygous Wilson's disease.
• According to Sallie et al, hepatic copper levels may vary considerably between different regions of the liver in Wilson's disease (up to 7 fold). In 2 of 15 patients with fulminant hepatic failure the hepatic copper level was normal.
