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Wilson Disease in Children: Serum Aminotransferases and Urinary Copper on Triethylene Tetramine Dihydrochloride (Trientine) Treatment

Arnon, Ronen*,†; Calderon, Judith Flores; Schilsky, Michael§; Emre, Sukru*,†,||; Shneider, Benjamin L*,†

Journal of Pediatric Gastroenterology and Nutrition: May 2007 - Volume 44 - Issue 5 - p 596–602
doi: 10.1097/MPG.0b013e3180467715
Original Articles: Hepatology & Nutrition
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Objectives: To evaluate the efficacy of and adherence to trientine and/or zinc therapy in children with Wilson disease (WD).

Materials and Methods: We retrospectively reviewed the clinical records of all children with WD in the pediatric liver/liver transplant program at our institution between 1998 and 2006.

Results: A total of 22 children with WD were evaluated and treated. Seven with fulminant disease required liver transplantation and 15 were treated with trientine and/or zinc. Ten of those 15 had follow-up for 12 to 60 months and 6 of the latter 10 were followed for 12 to 18 months. All 10 patients were started on a trientine treatment regimen. Mean alanine aminotransferase (ALT) levels decreased from 183 ± 103 IU at presentation (n = 10) to 80 ± 46 IU at 12 months (n = 10) and 66 ± 40 IU at 18 months (n = 7). Mean 24-hour urinary copper levels increased from 156 μg at presentation to 494 μg at 1 to 2 months, then decreased to 71 μg after 21 to 24 months of treatment. Three of 10 patients had normalized ALT levels and 1 patient with cirrhosis continued with normal ALT levels since presentation. Four of 10 patients were documented to be nonadherent, as manifested by increased ALT levels (99 ± 31 IU); 1 patient had previously normalized ALT levels. In 3 of 10 patients, ALT level decreased but remained at an abnormal level (93 ± 53 IU).

Conclusions: Trientine and/or zinc therapy is effective for children with WD. Nonadherence is a common cause of increased aminotransferase levels in patients with WD.

*Departments of Pediatrics

||Surgery

the Recanati-Miller Transplant Institute, Mount Sinai Medical Center, Mount Sinai School of Medicine

§Departments of Medicine, Center for Liver Disease and Transplantation

||Department of Surgery, Weill Cornell Medical Center, New York, New York

Department of Gastroenterology, Hospital de Pediatria, Centro Medico Nacional Siglo XXI, Instituto Mexicano del Seguro Social, Mexico City, Mexico

Received 17 October, 2006

Accepted 6 February, 2007

Address correspondence and reprint requests to Benjamin L. Shneider, MD, Children's Hospital of Pittsburgh, Pediatric Gastroenterology, 3705 Fifth Ave, Pittsburgh, PA 15213 (e-mail: benjamin.shneider@chp.edu).

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INTRODUCTION

Wilson disease (WD) is an autosomal recessive disorder of copper metabolism with a prevalence of 1 in 30,000 in the general population (1). The treatment of WD uses copper chelating agents such as penicillamine and trientine, zinc salts that block enteral copper absorption, and orthotopic liver transplantation, which may be lifesaving and curative for this disease (2). The efficacy of penicillamine and trientine is well documented, although there are limited data concerning trientine use in pediatric patients with WD. Penicillamine use is associated with numerous side effects (eg, early sensitivity reactions); some are severe and require drug discontinuation (3). Trientine appears to have a more favorable side effect profile than penicillamine (4–6). Zinc therapy is typically indicated for maintenance therapy in patients who have undergone chelation (7).

One of the parameters to assess clinical and biochemical response to treatment is evaluation of serum alanine aminotransferase (ALT) and aspartate aminotransferase (AST) activity. Lorio et al (8) evaluated the response of serum aminotransferase levels to penicillamine and zinc treatment in 109 patients. They found that 36% of their patients had high aminotransferase levels despite presumably appropriate treatment with penicillamine or zinc. Eighty-seven of the 109 patients were started on penicillamine, whereas 22 were started on zinc monotherapy. Seven of the 29 patients who continued to have high ALT levels while receiving penicillamine were switched to zinc. Five of the 11 zinc-treated patients had persistent high aminotransferase levels and were switched to penicillamine.

In our program, in the past 9 years, we have used trientine as the primary chelator for children with liver disease resulting from WD (Fig. 1). Typically, after 4 to 8 months of trientine therapy, when chelation has been achieved, zinc acetate is added (ie, combination therapy) until liver function tests are well on their way to improvement (usually 12–15 months after commencing treatment) and urinary copper levels are reduced. Subsequently, zinc monotherapy is used for maintenance. Twenty-four–hour urine copper and zinc levels are monitored during therapy. The urinary copper measurement permits assessment of chelation/copper overload, whereas urinary zinc measurement can document adherence to the medical regimen. The goal of therapy is normal or near-normal aminotransferase levels in the setting of normal or mildly increased 24-hour urine copper.

FIG. 1

FIG. 1

Little is known about the fluctuations of serum aminotransferase levels and urinary copper levels during treatment with trientine and/or zinc in children with WD. The aim of our retrospective study was to evaluate the efficacy of trientine and zinc therapy in children with WD.

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MATERIALS AND METHODS

We retrospectively reviewed the clinical records of all the children with WD evaluated and treated in the Division of Pediatric Hepatology and the Pediatric Liver/Liver Transplant Program at the Mount Sinai School of Medicine between 1998 and 2006. We reviewed and recorded clinical, laboratory, and histological features at diagnosis in all of the children enrolled in the study. Other causes of liver disease such as autoimmune liver disease, chronic viral hepatitis, α-1-antitrypsin deficiency, and other metabolic conditions were excluded by appropriate investigations.

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Diagnosis

The diagnosis of WD in the probands was based on the presence of liver disease and at least 2 of the following criteria (9):

  1. Positive family history
  2. Low serum ceruloplasmin level (<0.2 g/L)
  3. Elevated liver copper level (>250 μg/g dry weight)
  4. Presence of Kayser-Fleischer rings
  5. Increased baseline 24-hour urinary copper excretion >1 μmol/24 hours (63.5 μg/24 hours)
  6. Increased 24-hour urinary copper excretion after administration of 1000 mg penicillamine (>25 μmol/24 hours, 1590 μg/24 hours)
  7. Coombs negative hemolytic anemia

Complete blood counts, liver enzymes, prothrombin time, albumin and bilirubin levels, and 24-hour urine copper and zinc levels were assessed using commercially available methods during therapy. Acute liver failure (ALF) was defined by the presence of coagulopathy (International Normalized Ratio [INR] >2) with acute presentation of signs and symptoms of liver disease with or without encephalopathy (10).

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Medical Treatment

Initial therapy was directed at chelation of excess copper with trientine at a dose of 250 to 500 mg twice daily (approximately 20 mg · kg−1 · d−1; Fig. 1). Chelation by trientine after an initial increase in urinary copper was considered adequate if urine copper levels were <200 μg/24 hours and above the upper limit of normal. Long-term therapy, once adequate chelation was observed, was based on blocking intestinal absorption with zinc acetate given at a dose of 25 to 50 mg 2 times per day based on patient weight (approximately 1–2 mg · kg−1 · d−1 elemental zinc). The patients receiving trientine and zinc were instructed to take the medications with at least 1 hour difference in the time of administration to prevent chelation of the zinc by the trientine. The primary goals of treatment included maintenance of good clinical status, biochemical normalization of serum ALT and AST, activity and reduction of 24-hour urinary copper levels. Our goal for urinary copper excretion was a decrease from baseline measurements on the maximum dosage of trientine to an amount between 50 and 200 μg/d. When patients were receiving zinc therapy alone, the goal for urinary copper excretion was <100 μg/d. These parameters are based on data from the literature (5,11) and local experience. Twenty-four hour urine collections were part of routine monitoring in patients receiving zinc or trientine, enabling detailed assessment of a patient's clinical status, most notably including adherence to the medical regimen.

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Adherence

We investigated adherence to the medical regimen by clinical history, serum aminotransferase levels, and levels of urine copper and zinc. Nonadherence was defined as not taking the medications as prescribed, typically associated with biochemical sequelae (eg, increased aminotransferase levels, changes in urinary copper or zinc levels). For the purposes of this report, all instances of nonadherence were confirmed by the patients themselves. We suspected nonadherence in patients with a new increase in aminotransferase levels during medical therapy with trientine and/or zinc. A marked decrease in urine copper excretion to the normal range for those receiving trientine and an increase in urine copper excretion for those receiving zinc alone would also suggest possible nonadherence. A decrease in the 24-hour excretion of zinc in the urine to <2 mg for those taking zinc would suggest nonadherence or failure to take the medication apart from food or trientine (11). Patients with persistently high ALT activity during therapy were reevaluated for other causes of liver disease such as infection, autoimmune disease, drug-related toxicity, and obesity/fatty liver disease. We recorded any report of side effects and concomitant treatment. This retrospective study was approved by the institutional review board at Mount Sinai School of Medicine.

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RESULTS

Between July 1998 and January 2006, 22 children with WD (11 females) were evaluated and treated in the Division of Pediatric Hepatology and the Pediatric Liver/Liver Transplant Program at the Mount Sinai School of Medicine. The median age at diagnosis was 12.5 ± 3.2 years (range, 7–17 years).

Seven patients (32%) presented with ALF (5 females), with a mean age (±SD) of 13.0 ± 3.4 years (range, 7–16 years). All of the patients with ALF required liver transplantation despite aggressive medical management including albumin dialysis or plasmapheresis. The 15 other patients presented with increased liver enzyme levels, features of cirrhosis, neurologic symptoms, psychiatric manifestations, or fatigue, or were identified as part of screening because of an affected sibling. Ten of 15 patients receiving medical therapy had clinical and biochemical data with intermediate to long-term follow-up (between 12 and 60 months; Table 1). These 10 patients represent 300 patient-months of follow-up: 3 patients were followed for 1 year, 3 patients were followed for 18 months, 1 patient was followed for 30 months, and 3 patients were followed for 60 months.

TABLE 1

TABLE 1

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ALT in Follow-up

All 10 patients were started on chelation therapy with trientine. At 12 months of follow-up, all of the patients were receiving trientine or trientine and zinc therapy. All of the patients were transitioned to zinc monotherapy by 18 months of follow-up as shown in Figure 2.

FIG. 2

FIG. 2

Changes in ALT levels during therapy are seen in Table 2 and in Figure 2a for adherent patients and Figure 2b for nonadherent patients. Changes in AST were similar to those in ALT (Table 2). Three patients had normal ALT within 1 year of treatment. One was a patient who presented with cirrhosis and normal liver enzyme levels (patient 4; Fig. 2a). Another patient (patient 5; Fig. 2a) had normalized ALT levels after 30 months of treatment.

TABLE 2

TABLE 2

Nonadherence was identified in 4 patients by increased ALT levels coupled with low urinary levels of zinc (<2 mg/24 h). Each of these patients admitted to nonadherence. Two of the nonadherent patients (patients 7 and 8 in Fig. 2b) were treated again with trientine after receiving zinc monotherapy. The other 2 patients (patients 2 and 10 in Fig. 2b) were nonadherent to therapy during their early phase of treatment with trientine and zinc. They were reinstructed by our team regarding the importance of therapy and were closely monitored. The subsequent clinical course in these patients is not long enough to determine whether they have sustained adherence to their medical regimen and have commensurate improvement in their liver biochemistry findings.

Two patients had clinical evidence of cirrhosis with hypersplenism at presentation (patients 3 and 4 in Fig. 2a). Both had evidence of hepatic dysfunction manifest by coagulopathy and hypoalbuminemia (INR 1.8 and 1.9; albumin level 2.7 and 2.9 g/dL). After 2 years, the INR for both patients improved to 1.5. Albumin levels normalized after 3 to 6 months of chelation therapy. All of the other patients had normal hepatic synthetic function at presentation and throughout the reported therapy.

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Urine Copper Levels During the Study Period

Figure 3 shows the 24-hour urinary copper levels of 10 patients during a period of 60 months of follow-up. At presentation, the mean 24-hour urine copper level was 156 μg; it increased to a peak of 494 μg 1 to 2 months after the start of chelation therapy. After this peak, slow reduction of urine copper levels was observed, and by 1 year of treatment the mean urinary level was 72 μg/24 hours (range, 62–92), which is twice the upper normal limit.

FIG. 3

FIG. 3

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Treatment Side Effects

Significant side effects were not observed in any of the patients in this cohort. In 1 patient (patient 5; Fig. 2a) trientine was stopped after 12 months in response to elevated liver enzyme levels and zinc dosing was increased to 3 times daily, and the aminotransferase levels normalized thereafter. It is presumed that this patient had mild hepatic toxicity as a result of trientine therapy.

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DISCUSSION

The therapeutic goal in patients with WD is to restore or maintain normal liver function by removal of toxic copper stores in the liver and other sites in the body. This can be accomplished with oral chelating agents. Penicillamine, an effective chelating agent, has the potential for serious toxicity, including hypersensitivity reactions, bone marrow suppression, and development of autoimmune disease (3). Merle et al initially treated 126 patients with WD with penicillamine; 97 (71.3%) developed side effects and 31.3% experienced severe side effects such as neurological deterioration, pancytopenia, nephrotoxicity, polyneuropathy, optic neuritis, and polymyositis (4). Lorio et al reported that 13% of their pediatric patients with WD had to discontinue penicillamine treatment secondary to side effects (8). Trientine was introduced in 1969 as an alternative chelating agent for cases in which serious toxic reactions to penicillamine occur. We have not seen any of these side effects that are reported for penicillamine in our patients receiving trientine, although our sample size is fairly small and the follow-up is limited.

The rate and time of normalization of aminotransferase levels and urine copper levels in children with WD adherent to therapy are not well described. Aminotransferase levels seem to be a more reliable parameter of treatment efficacy in the early phase of WD than clinical signs such as fatigue, abdominal pain, or hepatomegaly (8). To our knowledge, our study is the first to evaluate serum aminotransferase activity in children with WD receiving trientine treatment. Penicillamine was used as a chelator in the recent report of Lorio et al, in which ALT levels normalized in 56 of 87 patients (64%) within a median of 17 months (range, 2–96 months) (8). Four of the 56 patients had a relapse of high aminotransferase levels; 1 of these did not comply with therapy. A total of 33.3% of patients (29 of 87) had diminished but persistent high aminotransferase levels at the end of follow-up. We have observed a similar phenomenon of persistent increases in ALT and AST in some patients receiving long-term treatment for WD. The clinical significance of this mild increase in aminotransferase levels is not clear. Marcellini et al reported that 6 of 22 patients treated with 5 years of zinc monotherapy had persistent increases in ALT (12). In our study only 3 patients of 10 had normalized ALT levels by 1 year of treatment. Two others had ALT levels less than twice the upper limit of normal. All of the patients showed improvement from their baseline measurements. In rare cases, high aminotransferase levels may be a side effect of the chelating agent and change to an alternative agent may be indicated.

Poor adherence to therapy may be responsible for the persistence of abnormal liver function test results. Confirmed nonadherence was identified in 4 of our patients with increased ALT levels. Dual therapy with trientine and zinc can be arduous and may contribute to some of the nonadherence in this cohort. It is not clear that dual therapy is necessary, and future approaches may include a direct transition from trientine to zinc. The limited time period of follow-up from the recognition and treatment of nonadherence does not permit analysis of the efficacy of efforts to improve compliance with the medical regimen. In a cohort of 141 patients receiving zinc therapy, Brewer et al (11) found that over a follow-up period of 5 to 10 years, approximately 10% of patients had serious nonadherence problems and another 20% had episodic nonadherence. It is difficult to assess the real percentage of patients, especially children, who do not take their medications appropriately, although we have shown that this is a common problem in a cohort of pediatric patients with autoimmune hepatitis (13). We and others have observed fulminant liver disease in patients with WD who are not adherent to their medical regimen. Despite the longstanding mildly increased level of ALT, none of our patients showed worsening of liver disease or developed other WD-related symptoms.

Twenty-four–hour urinary copper and zinc levels are important tools in diagnosis and monitoring treatment adherence and response in patients with WD (14). Our data demonstrate that with trientine, the peak copper excretion appears after 1 to 2 months and then there is a slow reduction of urine copper levels. Twenty-four–hour urinary copper levels remain increased up to twice the upper limit of normal after 1 to 2 years of treatment. Marcellini et al reported a decrease of 24-hour urinary copper excretion from a mean of 169 μg at diagnosis to 120 μg after 5 years of zinc treatment and to 113 μg after 10 years of treatment (12). Cupruresis is clearly more rapid with a chelating agent such as trientine. A low urinary zinc level in the setting of elevated aminotransferase levels and urinary copper levels is strongly suggestive of nonadherence with zinc therapy.

This study describes clinical experience and management of pediatric patients with WD. Trientine and/or zinc therapy, when taken, is effective and did not cause serious side effects. Zinc monotherapy after chelation may be efficacious as long-term maintenance management. Nonadherence is a common cause of increased liver enzyme levels in patients with WD receiving long-term therapy. We suggest routine blood and urine tests on a monthly basis in the first 6 months of treatment, bimonthly in the following 6 months, and every 3 months afterward as routine follow-up of patients with WD. Documented nonadherence may necessitate restarting chelation therapy and reinitiation of the follow-up program with monthly visits until there is biochemical improvement.

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Acknowledgment

The authors would like to thank Mr O. Arnon for his statistical and artistic contributions.

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REFERENCES

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Keywords:

Cirrhosis; Copper; Liver transplantation; Treatment adherence; Zinc

© 2007 Lippincott Williams & Wilkins, Inc.