Title: Diagnosis and treatment of Wilson disease: An update
Abstract: HepatologyVolume 47, Issue 6 p. 2089-2111 AASLD Practice GuidelinesFree Access Diagnosis and treatment of Wilson disease: An update† Eve A. Roberts, Eve A. Roberts Division of Gastroenterology, Hepatology and Nutrition, The Hospital for Sick Children, Toronto, Ontario, Canada Departments of Paediatrics, Medicine and Pharmacology, University of Toronto, Toronto, Ontario, CanadaSearch for more papers by this authorMichael L. Schilsky, Michael L. Schilsky Department of Medicine and Surgery, Division of Digestive Diseases, Section of Transplant and Immunology, Yale University Medical Center, New Haven, CTSearch for more papers by this author Eve A. Roberts, Eve A. Roberts Division of Gastroenterology, Hepatology and Nutrition, The Hospital for Sick Children, Toronto, Ontario, Canada Departments of Paediatrics, Medicine and Pharmacology, University of Toronto, Toronto, Ontario, CanadaSearch for more papers by this authorMichael L. Schilsky, Michael L. Schilsky Department of Medicine and Surgery, Division of Digestive Diseases, Section of Transplant and Immunology, Yale University Medical Center, New Haven, CTSearch for more papers by this author First published: 04 February 2008 https://doi.org/10.1002/hep.22261Citations: 889 † Potential conflict of interest: Nothing to report. All AASLD Practice Guidelines are updated annually. If you are viewing a Practice Guideline that is more than 12 months old, please visit www.aasld.org for an update in the material. AboutSectionsPDF ToolsRequest permissionExport citationAdd to favoritesTrack citation ShareShare Give accessShare full text accessShare full-text accessPlease review our Terms and Conditions of Use and check box below to share full-text version of article.I have read and accept the Wiley Online Library Terms and Conditions of UseShareable LinkUse the link below to share a full-text version of this article with your friends and colleagues. Learn more.Copy URL This guideline has been approved by the American Association for the Study of Liver Diseases (AASLD) and represents the position of the association. Preamble These recommendations provide a data-supported approach to the diagnosis and treatment of patients with Wilson disease. They are based on the following: (1) formal review and analysis of the recently-published world literature on the topic including Medline search; (2) American College of Physicians Manual for Assessing Health Practices and Designing Practice Guidelines1; (3) guideline policies, including the AASLD Policy on the Development and Use of Practice Guidelines and the American Gastroenterological Association Policy Statement on Guidelines2; (4) the experience of the authors in the specified topic. A significant problem with the literature on Wilson disease is that patients are sufficiently rare to preclude large cohort studies or randomized controlled trials; moreover, most treatment modalities were developed at a time when conventions for drug assessment were less stringent than at present. Intended for use by physicians, these recommendations suggest preferred approaches to the diagnostic, therapeutic, and preventive aspects of care. They are intended to be flexible, in contrast to standards of care, which are inflexible policies to be followed in every case. Specific recommendations are based on relevant published information. To characterize more fully the quality of evidence supporting recommendations, the Practice Guidelines Committee of the AASLD requires a class (reflecting benefit versus risk) and level (assessing strength or certainty) of evidence to be assigned and reported with each recommendation (Table 1, adapted from the American College of Cardiology and the American Heart Association Practice Guidelines3, 4). Table 1. Grading System for Recommendations Classification Description Class I Conditions for which there is evidence and/or general agreement that a given procedure or treatment is beneficial, useful, and effective. Class II Conditions for which there is conflicting evidence and/or a divergence of opinion about the usefulness/efficacy of a procedure or treatment. Class IIa Weight of evidence/opinion is in favor of usefulness/efficacy. Class IIb Usefulness/efficacy is less well established by evidence/opinion. Class III Conditions for which there is evidence and/or general agreement that a procedure/treatment is not useful/effective and in some cases may be harmful. Level of Evidence Description Level A Data derived from multiple randomized clinical trials or meta-analyses. Level B Data derived from a single randomized trial, or nonrandomized studies. Level C Only consensus opinion of experts, case studies, or standard-of-care. Abbreviations AASLD, American Association for the Study of Liver Diseases; BAL, British anti-Lewisite; MR, magnetic resonance; TM, tetrathiomolybdate; WD, Wilson disease. Introduction Copper is an essential metal that is an important cofactor for many proteins. The average diet provides substantial amounts of copper, typically 2-5 mg/day; the recommended intake is 0.9 mg/day. Most dietary copper ends up being excreted. Copper is absorbed by enterocytes mainly in the duodenum and proximal small intestine and transported in the portal circulation in association with albumin and the amino acid histidine to the liver, where it is avidly removed from the circulation. The liver utilizes some copper for metabolic needs, synthesizes and secretes the copper-containing protein ceruloplasmin, and excretes excess copper into bile. Processes that impair biliary copper excretion can lead to increases in hepatic copper content. Wilson disease (WD; also known as hepatolenticular degeneration) was first described in 1912 by Kinnear Wilson as “progressive lenticular degeneration,” a familial, lethal neurological disease accompanied by chronic liver disease leading to cirrhosis.5 Over the next several decades, the role of copper in the pathogenesis of WD was established, and the pattern of inheritance was determined to be autosomal recessive.6, 7 In 1993, the abnormal gene in WD was identified.8-10 This gene, ATP7B, encodes a metal-transporting P-type adenosine triphosphatase (ATPase), which is expressed mainly in hepatocytes and functions in the transmembrane transport of copper within hepatocytes. Absent or reduced function of ATP7B protein leads to decreased hepatocellular excretion of copper into bile. This results in hepatic copper accumulation and injury. Eventually, copper is released into the bloodstream and deposited in other organs, notably the brain, kidneys, and cornea. Failure to incorporate copper into ceruloplasmin is an additional consequence of the loss of functional ATP7B protein. The hepatic production and secretion of the ceruloplasmin protein without copper, apoceruloplasmin, result in the decreased blood level of ceruloplasmin found in most patients with WD due to the reduced half-life of apoceruloplasmin.11 WD occurs worldwide with an average prevalence of ∼30 affected individuals per million population.12 It can present clinically as liver disease, as a progressive neurological disorder (hepatic dysfunction being less apparent or occasionally absent), or as psychiatric illness. WD presents with liver disease more often in children and younger adult patients than in older adults. Symptoms at any age are frequently nonspecific. WD was uniformly fatal until treatments were developed a half-century ago. WD was one of the first liver diseases for which effective pharmacologic treatment was identified. The first chelating agent introduced in 1951 for the treatment of WD was British anti-Lewisite (BAL or dimercaptopropanol).13, 14 The identification and testing of an orally administered chelator, D-penicillamine, by John Walsh in 1956 revolutionized treatment of this disorder.15 Other treatment modalities have since been introduced, including zinc salts to block enteral copper absorption, tetrathiomolybdate (TM) to chelate copper and block enteral absorption, and orthotopic liver transplantation, which may be lifesaving and curative for this disorder. Clinical Features Over the years, diagnostic advances have enabled more systematic evaluation of individuals suspected to have WD prior to their development of neurologic symptoms. These include recognition of corneal Kayser-Fleischer rings,16 identification of reduced concentrations of ceruloplasmin in the circulation of most patients,17 and the ability to measure copper concentration in percutaneous liver biopsy specimens. More recently, molecular diagnostic studies have made it feasible either to define patterns of haplotypes or polymorphisms of DNA surrounding ATP7B which are useful for identification of first-degree relatives of newly diagnosed patients or to examine directly for disease-specific ATP7B mutations on both alleles of chromosome 13. Patients with cirrhosis, neurological manifestations, and Kayser-Fleischer rings are easily diagnosed as having WD because they resemble the original clinical description. The patient presenting with liver disease, who is at least 5 years old but under 40 years old, with a decreased serum ceruloplasmin and detectable Kayser-Fleischer rings, has been generally regarded as having classic WD.18 However, about half of the patients presenting with liver disease do not possess two of these three criteria and pose a challenge in trying to establish the diagnosis.19 Moreover, as with other liver diseases, patients may come to medical attention when their clinical disease is comparatively mild. Because at present, de novo genetic diagnosis is expensive and not universally available (and sometimes inconclusive), a combination of clinical findings and biochemical testing is usually necessary to establish the diagnosis of WD (Fig. 1). A scoring system has been devised to aid diagnosis, based on a composite of key parameters20; it has been subjected to preliminary validation in children.21 A molecular genetic strategy using haplotype analysis or direct mutation analysis may be effective in identifying affected siblings of probands. Figure 1Open in figure viewerPowerPoint Approach to diagnosis of Wilson disease (WD) in a patient with unexplained liver disease. Molecular testing means confirming homozygosity for one mutation or defining two mutations constituting compound heterozygosity. *Assure adequacy of urine collection. Conversion to SI units: CPN <20 mg/dL or 0.2 g/L; 24-hour urinary Cu >40 μg/day or 0.6 μmol/day. Note that normal ranges for CPN may vary slightly between laboratories. Abbreviations: CPN, ceruloplasmin; KF, Kayser-Fleischer. Spectrum of Disease. The spectrum of liver disease encountered in patients with WD is summarized in Table 2. The type of the liver disease can be highly variable, ranging from asymptomatic with only biochemical abnormalities to acute liver failure. Children may be entirely asymptomatic, with hepatic enlargement or abnormal serum aminotransferases found only incidentally. Some patients have a brief clinical illness resembling an acute viral hepatitis, and others may present with features indistinguishable from autoimmune hepatitis. Some present with only biochemical abnormalities or histologic findings of steatosis on liver biopsy. Many patients present with signs of chronic liver disease and evidence of cirrhosis, either compensated or decompensated. Patients may present with isolated splenomegaly due to clinically inapparent cirrhosis with portal hypertension. WD may also present as acute liver failure with an associated Coombs-negative hemolytic anemia and acute renal failure. Some patients have transient episodes of jaundice due to hemolysis. Low-grade hemolysis may be associated with WD when liver disease is not clinically evident. In one series, hemolysis was a presenting feature in 25 of 220 cases (11%); in these patients, hemolysis occurred as a single acute episode, recurrently, or was low-grade and chronic.22 In a series of 283 Japanese cases of WD, only three presented with acute hemolysis alone,23 but one-quarter of the patients who presented with jaundice also had hemolysis. Patients diagnosed with WD who have a history of jaundice may have previously experienced an episode of hemolysis. Table 2. Clinical Features in Patients with Wilson Disease Hepatic • Asymptomatic hepatomegaly • Isolated splenomegaly • Persistently elevated serum aminotransferase activity (AST, ALT) • Fatty liver • Acute hepatitis • Resembling autoimmune hepatitis • Cirrhosis: compensated or decompensated • Acute liver failure Neurological • Movement disorders (tremor, involuntary movements) • Drooling, dysarthria • Rigid dystonia • Pseudobulbar palsy • Dysautonomia • Migraine headaches • Insomnia • Seizures Psychiatric • Depression • Neurotic behaviours • Personality changes • Psychosis Other systems • Ocular: Kayser-Fleischer rings, sunflower cataracts • Cutaneous: lunulae ceruleae • Renal abnormalities: aminoaciduria and nephrolithiasis • Skeletal abnormalities: premature osteoporosis and arthritis • Cardiomyopathy, dysrhythmias • Pancreatitis • Hypoparathyroidism • Menstrual irregularities; infertility, repeated miscarriages Patients with apparent autoimmune hepatitis presenting in childhood, or in adults with a suspicion of autoimmune hepatitis that does not readily respond to therapy, should be assessed carefully for WD because elevated serum immunoglobulins and detectable nonspecific autoantibodies may be found in both conditions.24-26 Neurologic manifestations of WD typically present later than the liver disease, most often in the third decade of life, but they can present in childhood (Fig. 2). Earlier subtle findings may appear in pediatric patients, including changes in behavior, deterioration in schoolwork, or inability to perform activities requiring good hand-eye coordination. Handwriting may deteriorate, and cramped small handwriting as in Parkinson disease (micrographia) may develop. Other common findings in those presenting with neurologic disease include tremor, lack of motor coordination, drooling, dysarthria, dystonia, and spasticity. Because of pseudobulbar palsy, transfer dysphagia may also occur, with a risk of aspiration if severe. Dysautonomia may be present. Migraine headaches and insomnia may be reported; however, seizures are infrequent. Along with behavioral changes, other psychiatric manifestations include depression, anxiety, and even frank psychosis. Many of the individuals with neurologic or psychiatric manifestations may have cirrhosis, but frequently they are not symptomatic from their liver disease. Figure 2Open in figure viewerPowerPoint Approach to diagnosis of Wilson disease (WD) in a patient with a neurological disorder or psychiatric disease with or without liver disease. Molecular testing means confirming homozygosity for one mutation or defining two mutations constituting compound heterozygosity. Conversion to SI units: CPN <20 mg/dL or 0.2 g/L; 24-hour urinary Cu >40 μg/day or 0.6 μmol/day. Abbreviations: CPN, ceruloplasmin; KF, Kayser-Fleischer. Patients with WD may present with important extrahepatic manifestations apart from neurologic or psychiatric disease: renal abnormalities including aminoaciduria and nephrolithiasis,27-29 skeletal abnormalities such as premature osteoporosis and arthritis,30 cardiomyopathy,31-33 pancreatitis,34 hypoparathyroidism,35 and infertility or repeated miscarriages.36-39 Age. Even when presymptomatic siblings are excluded, the age at which WD may present or be diagnosed is both younger and older than generally appreciated, though the majority present between ages 5 and 35. WD is increasingly diagnosed in children younger than 5 years old, with atypical findings in children under 2 years old,40-44 cirrhosis in a 3-year-old,45 and acute liver failure in a 5-year-old.46 The oldest patients with WD, confirmed by molecular studies demonstrating ATP7B mutations, were in their early 70s.47, 48 Although the upper age limit for consideration of WD is generally stated as <40 years, when other concurrent neurologic or psychiatric symptoms and histologic or biochemical findings suggest this disorder, further evaluation should be carried out in older individuals. Kayser-Fleischer Ring. Kayser-Fleischer rings represent deposition of copper in Deçemet's membrane of the cornea. When they are visible by direct inspection, they appear as a band of golden-brownish pigment near the limbus. A slit-lamp examination by an experienced observer is required to identify Kayser-Fleischer rings in most patients. They are not entirely specific for WD, because they may be found in patients with chronic cholestatic diseases49-51 and in children with neonatal cholestasis52; however, these disorders can usually be distinguished from WD on clinical grounds. Large series of patients with WD show that Kayser-Fleischer rings are present in only 44%-62% of patients with mainly hepatic disease at the time of diagnosis.19, 53-56 In children presenting with liver disease, Kayser-Fleischer rings are usually absent.57-59 Kayser-Fleischer rings are almost invariably present in patients with a neurological presentation, but even in these patients they may be absent in 5% of cases.19, 60 Kayser-Fleischer rings are rarely reported with chronic cholestatic liver disease. Other ophthalmological changes may be found. Sunflower cataracts, also found by slit-lamp examination, represent deposits of copper in the lens.61 These typically do not obstruct vision. Both Kayser-Fleischer rings and sunflower cataracts will gradually disappear with effective medical treatment or following liver transplant, though the rate of disappearance does not correlate with resolution of clinical symptoms.62, 63 The reappearance of either of these ophthalmologic findings in a medically treated patient in whom these had previously disappeared suggests noncompliance with therapy. Recommendations: 1 WD should be considered in any individual between the ages of 3 and 55 years with liver abnormalities of uncertain cause. Age alone should not be the basis for eliminating a diagnosis of WD (Class I, Level B). 2 WD must be excluded in any patient with unexplained liver disease along with neurological or neuropsychiatric disorder (Class I, Level B). 3 In a patient in whom WD is suspected, Kayser-Fleischer rings should be sought by slit-lamp examination by a skilled examiner. The absence of Kayser-Fleischer rings does not exclude the diagnosis of WD, even in patients with predominantly neurological disease (Class I, Level B). Diagnostic Testing: Biochemical Liver Tests. Serum aminotransferase activities are generally abnormal in WD except at a very early age. In many individuals, the degree of elevation of aminotransferase activity may be mild and does not reflect the severity of the liver disease. Ceruloplasmin. This 132-kDa protein is synthesized mainly in the liver and is an acute phase reactant. The vast majority of the protein is secreted into the circulation from hepatocytes as a copper-carrying protein containing six copper atoms per molecule of ceruloplasmin (holoceruloplasmin), and the remainder as the protein lacking copper (apoceruloplasmin). Ceruloplasmin is the major carrier for copper in the blood, accounting for 90% of the circulating copper in normal individuals. Ceruloplasmin is a ferroxidase. It is a nitric oxide oxidase thus influencing nitric oxide homeostasis,64 and it acts as an oxidase for substrates such as p-phenylamine diamine65 and o-dianisidine,66 which forms the basis for enzymatic assays for the protein. Levels of serum ceruloplasmin may be measured enzymatically by their copper-dependent oxidase activity toward these substrates, or by antibody-dependent assays such as radioimmunoassay, radial immunodiffusion, or nephelometry. Results generally are regarded as equivalent,67 but immunologic assays routinely in clinical use may overestimate ceruloplasmin concentrations because they do not discriminate between apoceruloplasmin and holoceruloplasmin. This makes serum ceruloplasmin as a diagnostic criterion difficult to interpret. Serum ceruloplasmin concentrations are elevated by acute inflammation and in states associated with hyperestrogenemia such as pregnancy, estrogen supplementation, and use of some oral contraceptive pills. Levels of serum ceruloplasmin are physiologically very low in early infancy to the age of 6 months, peak at higher than adult levels in early childhood (at approximately 300-500 mg/L), and then settle to the adult range. Serum ceruloplasmin is typically decreased in patients with WD, but serum ceruloplasmin may be low in certain other conditions with marked renal or enteric protein loss or with severe end-stage liver disease of any etiology or with various rare neurologic diseases.68 Low levels of ceruloplasmin and/or appearance of pancytopenia have been recognized in patients with copper deficiency when trace elements were not added to parenteral alimentation69 and in patients with Menkes disease, an X-linked disorder of copper transport due to mutations in ATP7A.70 Patients with the rare disorder aceruloplasminemia lack the protein entirely due to mutations in the ceruloplasmin gene on chromosome 3, but these patients may exhibit hemosiderosis, not copper accumulation.71, 72 A serum ceruloplasmin level <200 mg/L (<20 mg/dL, though there are different normal ranges depending on the laboratory) has been considered consistent with WD, and diagnostic if associated with Kayser-Fleischer rings. A prospective study of using serum ceruloplasmin alone as a screening test for WD in patients referred with liver disease showed that subnormal ceruloplasmin had a very low positive predictive value: of 2867 patients tested, only 17 had subnormal ceruloplasmin and only one of these was found to have WD.73 Other recent reports indicate the limitations of ceruloplasmin measurements for diagnosis. In one series, 12 of 55 patients with WD had normal ceruloplasmin and no Kayser-Fleischer rings.19 In another study, six of 22 patients with WD had serum ceruloplasmin > 170 mg/L (>17 mg/dL), and of these, four had no Kayser-Fleischer rings.53 In children, three of 26 patients had ceruloplasmin >150 mg/L (>15 mg/dL)59 and in an early study, 10 of 28 children with WD had serum ceruloplasmin ≥200 mg/L (≥20 mg/dL).74 However, most reports based on several decades of experience from the mid-1950s onward indicate that 90%-100% of patients had serum ceruloplasmin in the subnormal range.75-77 Using serum ceruloplasmin to identify patients with WD is further complicated by overlap with some heterozygotes.75 Approximately 20% of heterozygotes have decreased levels of serum ceruloplasmin. Uric Acid. Serum uric acid may be decreased at presentation with symptomatic hepatic or neurological disease because of associated renal tubular dysfunction (Fanconi syndrome). Insufficient evidence is available to determine the predictive value of this finding. Recommendation 4 An extremely low serum ceruloplasmin level (<50 mg/L or <5 mg/dL) should be taken as strong evidence for the diagnosis of WD. Modestly subnormal levels suggest further evaluation is necessary. Serum ceruloplasmin within the normal range does not exclude the diagnosis (Class I, Level B). Serum Copper. Although a disease of copper overload, the total serum copper (which includes copper incorporated in ceruloplasmin) in WD is usually decreased in proportion to the decreased ceruloplasmin in the circulation. In patients with severe liver injury, serum copper may be within the normal range despite a decreased serum ceruloplasmin level. In the setting of acute liver failure due to WD, levels of serum copper may be markedly elevated due to the sudden release of the metal from tissue stores. Normal or elevated serum copper levels in the face of decreased levels of ceruloplasmin indicate an increase in the concentration of copper not bound to ceruloplasmin in the blood (non–ceruloplasmin bound copper). The serum non–ceruloplasmin bound copper concentration has been proposed as a diagnostic test for WD. It is elevated above 25 μg/dL (250 μg/L) in most untreated patients (normal <15 μg/dL or <150 μg/L). Non–ceruloplasmin bound copper is usually estimated from the serum copper and ceruloplasmin. The amount of copper associated with ceruloplasmin is approximately 3.15 μg of copper per milligram of ceruloplasmin. Thus, the non–ceruloplasmin bound copper is the difference between the serum copper concentration in micrograms per deciliter and three times the serum ceruloplasmin concentration in milligrams per deciliter.78, 79 (For Système International (SI) units, both serum copper and ceruloplasmin should be expressed as “per liter”; the conversion factor is unchanged, but the normal reference value is <150 μg/L.) The serum non–ceruloplasmin bound copper concentration may be elevated in acute liver failure of any etiology, not only in WD,57, 80 and it may be elevated in chronic cholestasis81 and in cases of copper intoxication from ingestion or poisoning. The major problem with non–ceruloplasmin bound copper as a diagnostic test for WD is that it is dependent on the adequacy of the methods for measuring both serum copper and ceruloplasmin. If the serum copper measurement is inaccurate or, more commonly, if the serum ceruloplasmin measurement overestimates holoceruloplasmin, then the estimated non–ceruloplasmin bound copper concentration cannot be interpreted because it may be a negative number. This determination may be of more value in patient monitoring of pharmacotherapy than in the diagnosis of WD. Non–ceruloplasmin bound copper concentration <5 μg/dL (<50 μg/L) may signal systemic copper depletion that can occur in some patients with prolonged treatment. Urinary Copper Excretion. The amount of copper excreted in the urine in a 24-hour period may be useful for diagnosing WD and for monitoring of treatment. The 24-hour urinary excretion of copper reflects the amount of non–ceruloplasmin bound copper in the circulation. Basal measurements can provide useful diagnostic information so long as copper does not contaminate the collection apparatus and the urine collection is complete. There is too much variability in the copper content in spot urine specimens for them to be utilized. Volume and total creatinine excretion in the 24-hour urine collection are measured to assess completeness. The conventional level taken as diagnostic of WD is >100 μg/24 hours (>1.6 μmol/24 hours) in symptomatic patients.56, 80 Recent studies indicate that basal 24-hour urinary copper excretion may be <100 μg at presentation in 16%-23% of patients diagnosed with WD.19, 58, 59 The reference limits for normal 24-hour excretion of copper vary among clinical laboratories. Many laboratories take 40 μg/24 hours (0.6 μmol/24 hours) as the upper limit of normal. This appears to be a better threshold for diagnosis.53, 82 Interpreting 24-hour urinary copper excretion can be difficult due to overlap with findings in other types of liver disease, and heterozygotes may also have intermediate levels.80 Patients with certain chronic liver diseases, including autoimmune hepatitis, may have basal 24-hour copper excretion in the range of 100-200 μg/24 hours (1.6-3.2 μmol/24 hours).83 In one study of patients with chronic active liver disease, five of 54 patients had urinary copper excretion above 100 μg/24 hours84; overlap has also been reported in children with autoimmune hepatitis.74 Urinary copper excretion with D-penicillamine administration may be a useful diagnostic adjunctive test. This test has only been standardized in a pediatric population57 in which 500 mg of D-penicillamine was administered orally at the beginning and again 12 hours later during the 24-hour urine collection, irrespective of body weight. Compared to a spectrum of other liver diseases including autoimmune hepatitis, primary sclerosing cholangitis and acute liver failure, a clear differentiation was found when >1600 μg copper/24 hours (>25 μmol/24 hours) was excreted. Recent reevaluation of the penicillamine challenge test in children found it valuable for the diagnosis of WD in patients with active liver disease (sensitivity 92%) but poor for excluding the diagnosis in asymptomatic siblings (sensitivity only 46%).85 Others have found the predictive value of the 25 μmol/24 hours cut-off to be <100%.86, 87 This test has been used in adults, but many of the reported results of this test in adults used different dosages and timing for administration of D-penicillamine.19, 80, 83 Measurement of the basal 24-hour urinary excretion of copper forms part of the assessment to screen siblings for WD, but it has not been validated as the sole test for screening. Recommendations: 5 Basal 24-hour urinary excretion of copper should be obtained in all patients in whom the diagnosis of WD is being considered. The amount of copper excreted in the 24-hour period is typically >100 μg (1.6 μmol) in symptomatic patients, but finding >40 μg (>0.6 μmol or >600 nmol) may indicate WD and requires further investigation (Class I, Level B). 6 Penicillamine challenge studies may be performed for the purpose of obtaining further evidence for the diagnosis of WD in symptomatic children if basal urinary copper excretion is <100 μg/24 hours (1.6 μmol/24 hours). Values for the penicillamine challenge test of >1600 μg copper/24 hours (>25 μmol/24 hours) following the administration of 500 mg of D-penicillamine at the beginning and again 12 hours later during the 24-hour urine collection are found in patients with Wilson disease. The predictive value of this test in adults is