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Clinical Studies |
Division of Endocrinology and Metabolism, Departments of Medicine (K.V.W., L.A.B.) and Pediatrics (S.N., D.B.), and The Thomas E. Starzl Transplantation Institute (J.R.), University of Pittsburgh School of Medicine, Pittsburgh, Pennsylvania 15261
Address all correspondence and requests for reprints to: Lynn A. Burmeister, M.D., E1140 Biomedical Science Tower, University of Pittsburgh School of Medicine, Pittsburgh, Pennsylvania 15261. E-mail: Burmeist{at}Novell1.Dept-Med.Pitt.Edu
| Abstract |
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A MEDLINE search for English language cases of PTU hepatotoxicity between 1966 and April 1996 was performed, and additional cases were cross-referenced. Twenty-seven cases were selected based on the availability of information on patient management after the onset of hepatotoxicity. Eighty-five percent of the selected cases met this criterion. A detailed summary of the management of two cases of PTU hepatotoxicity at our institutions is also provided.
Although most patients recovered once PTU was stopped, seven patients died. Patients with PTU hepatotoxicity who survived were more likely to have received 131I during the course of their illness than those who died (P < 0.03, by Fishers exact test). In our two patients, hyperbilirubinemia was linearly associated with progressively decreasing T4 levels (r = 0.91; P < 0.001) despite the presence of clinical thyrotoxicosis in one of the patients. These findings demonstrate the need for appropriate clinical evaluation and treatment of thyroid disease during the course of hepatotoxicity. Additionally, we report the first pediatric patient with PTU hepatotoxicity to undergo liver transplantation. The emerging role of liver transplantation in these patients is discussed.
| Introduction |
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| Case Reports |
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A 14-yr-old female of Latin American descent presented in April with complaints of heat intolerance, weight gain, tremor, restless sleep, intermittently loose stools, and a 5-kg weight gain. She noted diminished school performance due to poor concentration. There was progressive prominence of her eyes. Menarche had occurred at 10 yr, and she had noted a 1-yr history of menstrual irregularity. Her past medical history was unremarkable, and she took no medications. Family history was negative for thyroid or liver disease.
On initial examination she had tachycardia, tremor, exophthalmos, and a
goiter with a prominent bruit. Laboratory evaluation showed
thyrotoxicosis (Table 1
), positive TSH receptor
antibodies (66%; normal, <12%), and strongly positive antimicrosomal
(5540 IU/mL; normal, <120) and antithyroglobulin (7625 IU/mL; normal,
<120 IU/mL) antibodies. In addition, she had mild
-glutamyltransferase and alkaline phosphatase elevations (Table 1
).
She was diagnosed with Graves disease and was treated with 400 mg PTU
daily (6.0 mg/kg·day) and 80 mg propranolol daily (1.2 mg/kg·day).
During the subsequent 10 weeks, the PTU dosage was increased to 450 mg
daily (6.7 mg/kg·day). Her symptoms and thyroid studies gradually
improved, and
-glutamyltransferase normalized, but her other hepatic
studies rose slightly (Table 1
).
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One week later, she presented with fatigue, vomiting, diarrhea, yellow
sclerae, and dark urine. She had tachycardia, icterus, exophthalmos,
jaundice, goiter with a prominent bruit, and tremor. Laboratory
evaluation showed continued thyrotoxicosis and severe hepatocellular
damage (Table 1
, 8/31). Hepatitis A, B, and C screen, and antinuclear
and antismooth muscle antibodies were negative. PTU was discontinued,
and propranolol was maintained at 240 mg/day. Radioiodine uptake was
42% at 24 h. The hepatic dysfunction progressed to fulminant
hepatic failure (Table 1
) with worsening coagulopathy and symptoms of
hepatic encephalopathy. The patient was transferred to the Childrens
Hospital of Pittsburgh. Thyroid studies showed normal total and free
T4 levels (Table 1
, 9/11). Viral hepatitis studies were
again negative. Propranolol therapy was decreased to 120 mg/day, and
Lugols solution (five drops, three times daily) was begun. She
developed progressive hyperbilirubinemia with a declining total
T4 level (Table 1
). Open liver biopsy revealed virtually
complete hepatocellular necrosis. The following day, she received an
orthotopic liver transplant without complication.
Hepatic studies returned to normal within 2 days of transplantation
(Table 1
). Immunosuppression was maintained with tacrolimus and
prednisone. Lugols solution and propranolol were continued, and she
had further improvement of thyrotoxicosis and exophthalmos over the
following 2 weeks. Eighteen days after liver transplantation she
underwent a subtotal thyroidectomy. One year later, the patient is in
good health and receiving thyroid hormone replacement and minimal
immunosuppressive therapy.
Case 2
A 54-yr-old white man with a history of heavy alcohol use 15 yr previously presented in December with dyspnea on exertion, palpitations, nausea, pruritus, and right upper quadrant tenderness. Over the preceding 4 months he had lost 8.2 kg despite no change in his appetite. Two weeks before presentation he developed frequent stools. He also complained of heat intolerance, difficulty sleeping, and tremors. Although he readily admitted to drinking heavily in the past, he currently reported drinking six cans of beer per week. There was no history of medication use, hepatitis, blood transfusions, homosexual contact, iv drug use, or recent travel. He denied any significant past medical illnesses. Family history was negative for thyroid or liver diseases.
The patient was very anxious. The heart rate was 140 beats/min and
irregular, with a blood pressure of 140/80 mm Hg. The skin was warm,
and there were spider angiomas. The sclerae were anicteric, there was
no proptosis, and extraocular muscle function was intact. The thyroid
gland was not palpable. There were no cardiac murmurs, and the lungs
were clear to auscultation. There was moderate right upper quadrant
tenderness, but the liver was not enlarged. There was no peripheral
edema. An electrocardiogram showed atrial fibrillation with a rapid
ventricular rate. Laboratory evaluation showed elevation of hepatic
enzymes and bilirubin as well as thyrotoxicosis (Table 2
) with positive antimicrosomal antibodies (1:6400
titer; normal, <1:100) and normal thyroid-stimulating Ig (83%;
normal, 70150%). Right upper quadrant ultrasound showed diffuse
dilation of intrahepatic ducts, normal extrahepatic ducts, and no
gallstones. Computed tomography (CT) of the liver and spleen with oral
gastrografin was normal. A hepatobiliary scan with cholecystokinin
showed no findings to suggest acute cholecystitis. Hepatitis B surface
antigen, hepatitis B surface antibodies, hepatitis B core antibodies,
and hepatitis C antibodies were all negative.
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Twelve days later he presented with jaundice, right upper quadrant
pain, worsening hepatic enzyme abnormalities, and persistent
thyrotoxicosis (Table 2
, 12/20). PTU was discontinued. Hepatitis A
antibodies and hepatitis C PCR were negative. A repeat ultrasound of
the liver showed no dilated intra- or extrahepatic ducts. A CT scan of
the abdomen with iv contrast showed slight prominence of the
intrahepatic ducts. Methimazole was given on the seventh hospital day,
but was discontinued on the ninth hospital day due to persistent
hepatic enzyme elevations. He received Lugols solution (three drops
daily) for 2 days.
He was transferred to the University of Pittsburgh Medical Center on
December 29. On arrival, he did not appear clinically thyrotoxic
despite an elevated free T4 index of 24.5 (Table 2
).
Serologies were again negative for hepatitis A, B, and C. Antinuclear,
antimitochondrial, and antismooth muscle antibodies were negative.
Liver biopsy revealed chronic liver disease with an acute insult and
mild eosinophilia due to a drug, viral, or autoimmune reaction. He was
placed on the transplant waiting list and discharged.
Three days later he was readmitted with nausea and vomiting due to a
duodenal ulcer. He appeared clinically euthyroid, but the free
T4 index remained elevated at 17.6 (Table 2
, 1/14). He
developed progressive hyperbilirubinemia with a declining total
T4 level (Table 2
). Liver transplantation was delayed due
to atrial fibrillation, hypotension, fever, and acute renal failure.
The possibility of thyroid storm was considered. Radioiodine uptake was
8.24% at 24 h. A trial of propranolol treatment induced
hypotension. He was given hydrocortisone (150 mg daily) and
supersaturated potassium iodide (five drops every 6 h).
Antibiotics were given for subacute bacterial peritonitis and a urinary
tract infection. Recurrent fevers and unstable hemodynamics continued
despite repeatedly negative blood, peritoneal, and urine cultures. He
died of multisystem organ failure within 5 weeks of presentation. A
free T4 level was high on the day of death (Table 2
,
1/26).
| Materials and Methods |
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Thyroid function tests on the two cases presented were obtained through
five different institutions. The specific tests used are reported in
Tables 1
and 2
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Statistical analysis was performed with the Statistical Package for the
Social Sciences using t tests, Wilcoxon rank sum test,
ANOVA,
2, and Fishers exact test where appropriate.
P < 0.05 is considered significant.
| Results |
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The characteristics of the patients who developed PTU-associated
hepatic disease are shown in Table 3
. One female who
received PTU via transplacental passage and manifested symptoms at the
age of 5 days was not included (6). There were more case reports of PTU
hepatotoxicity in women than men, with an overall female to male ratio
of 8.3:1. When patients who survived were compared to those who died,
there was no difference in age, dose of PTU, or months of continuous
PTU therapy before the onset of PTU hepatotoxicity (Table 3
). Most
patients (75.0%) did not have hepatic function tests performed before
the initiation of PTU therapy (Table 3
). Baseline hepatic function test
abnormalities were reported in our two cases and three others (2, 14, 20).
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PTU was discontinued in all reported cases once hepatotoxicity was
recognized. Thyroid function studies at presentation with hepatoxicity
were not described in 38.1% of the reports (Table 4
).
When noted, the thyroidal state was either normal or thyrotoxic. The
rationale for treatment of hyperthyroidism at the time patients
presented with hepatotoxicity was not always stated. Some cases were
described as being euthyroid but received treatment for
hyperthyroidism, whereas others were described as hyperthyroid yet
received no treatment for hyperthyroidism.
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Propranolol alone (9, 11, 21, 22) or methimazole (8, 15, 16) was used without complication in a total of seven cases. Including our two patients, four patients received oral iodide either as the primary treatment of hyperthyroidism before thyroidectomy or after 131I therapy (7, 14). The first case presented is the first reported patient to undergo thyroidectomy as part of the management of hyperthyroidism.
Diagnosis and treatment of hepatotoxicity
The diagnosis of PTU hepatotoxicity was supported by either liver biopsy in our 2 cases and 14 others (3, 10, 14, 16, 18, 19, 20, 21, 22, 23) or postmortem examination (9, 24). Liver histology showed varying degrees of liver necrosis, although exceptions were found (10, 19). The association between PTU and hepatic injury was confirmed by rechallenge with PTU in 1 case (16). Nine patients had lymphocyte sensitization studies performed at various times after the onset of hepatotoxicity. Lymphocyte sensitization to PTU was positive in 5 patients (6, 10, 14, 15, 18) and negative in 4 patients (4, 11, 12, 19).
Most of the patients had resolution of hepatic function abnormalities upon discontinuation of the antithyroid drug followed by supportive therapy alone (2, 3, 4, 5, 6, 7, 9, 10, 11, 12, 13, 14, 15, 16, 17, 18, 19, 20). Three patients received steroids, but the reasons for steroid therapy were not uniform and included treatment for possible autoimmune hepatitis (3), rash (10), or unexplained hypotension in the second case presented here. Two patients, including the first case presented here, underwent liver transplantation for PTU-associated hepatic failure. The other patient who received a liver transplant was pregnant when she developed PTU hepatotoxicity and successfully received a liver transplant while pregnant, but suffered fetal death (8). Seven patients died of PTU hepatotoxicity (9, 13, 21, 22, 23, 24). The deaths occurred between 117 weeks (mean, 39 ± 14 days) after presentation with hepatotoxicity. Deaths were attributed to complications of hepatic failure, such as deepening coma with brain death (9, 21), hepatorenal syndrome (22), sepsis (13, 24), or gastrointestinal bleeding (23).
| Discussion |
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PTU hepatotoxicity occurs at all ages and, like thyroid disease (33), shows a female predominance. The ranges for both PTU dose and duration of therapy in the patients who developed hepatotoxicity are wide. The presentation of PTU hepatotoxicity is clinically nonspecific. Abnormalities or worsening of liver function tests suggest the diagnosis. However, a search for other potential causes of hepatic dysfunction remains necessary. Nonspecific hepatocellular necrosis is typically found on liver biopsy (3, 9, 14, 16, 20, 21, 22, 23, 24). Based on the severity of the disease process, the pathological findings may range from early signs of hepatocellular inflammation and swelling to submassive hepatic necrosis. The mechanism of antithyroid drug hepatotoxicity is not known, although positive lymphocyte sensitization studies in some patients who developed PTU hepatotoxicity suggest an immune reaction to PTU. Because both hyperthyroidism and hepatic dysfunction may progress despite discontinuation of PTU, appropriate management of both diseases is critical.
Upon recognition of hepatotoxicity, PTU should be discontinued. With supportive therapy, most patients should recover. However, death due to complications of liver failure occurred in 25% of the population reported herein. Thus, early recognition of fulminant hepatic failure and intervention may be necessary. Several early prognostic factors are known to be associated with survival rates of less than 20% in fulminant hepatic failure (34). These include patient age (<11 and >40 yr), duration of jaundice (>7 days) before the onset of encephalopathy, serum bilirubin concentration (>300 µmol/L), and prothrombin time (>50 s). The etiology of fulminant hepatic failure may be the most important variable predicting outcome in medically managed patients, with a survival rate of only 13.6% in patients with idiosyncratic drug reactions (34). If patients who receive a liver transplant are included in this group, the overall survival rate is increased to 2030% (35). Thus, liver transplantation should be considered based on close clinical and laboratory follow-up in patients with PTU hepatotoxicity. This procedure proved necessary and was lifesaving in two patients, including the pediatric patient reported herein (8). To this end, early referral to a transplantation center may improve the chances of finding a suitable donor organ (34). The presence of encephalopathy, hypoprothrombinemia, or the hepatorenal syndrome may hasten the need for transplantation (36). Lastly, plasmapheresis or hemodialysis with hemoperfusion for correction of coagulopathy and encephalopathy may be effective in providing time for recovery of the liver or as a bridge to transplantation (37).
The interpretation of thyroid function tests and the treatment of
hyperthyroidism in the unique setting of PTU-associated hepatotoxicity
presents another challenge. Interactions between both thyroid and
hepatic disease as well as the patients clinical status must be
considered. Biochemical tests alone may not reflect the patients true
thyroid status. Acute hepatitis may increase the concentration of
thyroid hormone-binding globulin, causing an increase in the total
T4 level and a decrease in the thyroid hormone binding
ratio (38). With progressive hepatic dysfunction, the interaction
between thyroid and hepatic disease becomes even more important. Both
cases presented showed an inverse linear relationship between total
T4 level and serum bilirubin (r = 0.91;
P < 0.001) (Fig. 1
). This relationship has been
observed in other patient populations (39). Yet, in case 2, when total
T4 was unmeasurable, free T4 (by equilibrium
dialysis) was markedly elevated, suggesting persistent, insufficiently
treated hyperthyroidism. The low total T4 level may have
been due to a decreased concentration of thyroid hormone-binding
proteins (40, 41). Bilirubin may also have interfered with the
measurement of T4 by lowering the affinity of
T4 for thyroid hormone-binding proteins (42). Furthermore,
because bilirubin is a marker of the severity of hepatic dysfunction,
the correlation between bilirubin and total T4 may only
reflect the progression of nonthyroidal illness (40). Because free
T4 may be elevated when total T4 is normal,
low, or unmeasurable in hyperthyroidism associated with severe illness
(40, 43, 44), the measurement of free T4 levels may aid in
the interpretation of the patients thyroidal status.
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The use of iodide alone after recognition of hepatotoxicity merits further comment. In most patients, iodide doses of 114 mg produce maximal suppression of thyroid hormone levels within 714 days and last from 1 to more than 50 days (46, 47). Because iodide can also provide substrate for thyroid hormone synthesis, it is usually used in combination with antithyroid drugs. In the two cases presented, iodide was administered in isolation because of PTU hepatotoxicity. However, because the cause of hyperthyroidism is variable (Graves disease vs. toxic multinodular goiter), this therapy cannot be recommended in all patients. In the first case presented, who had Graves disease, iodide treatment controlled thyrotoxicosis until a thyroidectomy could be performed. The etiology of hyperthyroidism in the second case may not have been Graves disease but, rather, toxic multinodular goiter, and it is theoretically possible, although undocumented, that iodide treatment may have exacerbated his thyrotoxic condition.
An important question that could not be answered by this study is whether patients with preexisting liver function test abnormalities or hepatic disease are at increased risk of developing hepatotoxicity. PTU has been administered in a clinical trial to patients with alcoholic hepatitis with associated decreased mortality and without reported worsening of liver function (48). PTU hepatotoxicity has been reported in patients with both normal and abnormal baseline liver function tests. Up to 72% of patients with hyperthyroidism and presumably normal liver function may have an elevation of at least one hepatic enzyme (49). Alkaline phosphatase elevations are most commonly reported; however, the bone isoenzyme predominates (50, 51). Transaminase elevations may be due to thyrotoxicosis-induced increased hepatic oxygen consumption (52, 53) with inadequate compensatory hepatic blood flow (52). In one prospective study, thyrotoxic patients with mild baseline alanine aminotransferase (ALT) elevations had either an increase or a decrease in ALT with PTU treatment. When PTU was continued at a reduced dose, ALT levels normalized in most patients (31). Liver function test elevations were present in both of our cases before the initiation of PTU therapy; however, the second case had a greater elevation of ALT before starting PTU therapy than those previously reported (49). Marked baseline elevations in liver enzymes require investigation for underlying liver disease.
This report does not include data on methimazole hepatotoxicity, for
which there have been 21 reported cases (7, 54, 55, 56, 57, 58, 59, 60, 61, 62, 63, 64, 65, 66, 67, 68, 69, 70) and 3 (14%)
reported deaths (7, 69, 70). The percentage of deaths from methimazole
hepatotoxicity did not reach statistical significance compared to the
percentage of reported deaths in patients with PTU hepatotoxicity (by
2 analysis using Fishers exact test, P
= 0.48). Patients with methimazole hepatotoxicity more commonly have
cholestatic changes on liver biopsy.
In summary, in the past 50 years there have been several changes that
can affect the management of PTU-associated hepatotoxicity, including
improvements in thyroid hormone assays, additional forms of antithyroid
therapy, and liver transplantation. Recommendations for the management
of these patients are shown in Table 5
. No specific
factors identify the risk of hepatotoxicity in an individual patient.
Baseline hepatic function abnormalities may be related to
hyperthyroidism (31, 49) and do not necessarily contraindicate the use
of antithyroid drugs. The available data are insufficient to establish
whether baseline hepatic function test abnormalities are more common in
patients with PTU hepatotoxicity. If significant hepatic enzyme
abnormalities develop during the course of PTU therapy, the drug should
be discontinued immediately, and definitive treatment of the
hyperthyroidism should consist of 131I therapy. Because of
the possible autoimmune etiology of PTU hepatotoxicity (6, 18) and
recurrence of hepatotoxicity with drug rechallenge (16), PTU should not
be reinstituted even after resolution of hepatotoxicity or liver
transplantation. Appropriate evaluation of the patients thyroid
status requires assessment of both physical findings and accurate
measurement of free T4 levels. Close clinical follow-up is
necessary because hepatic failure can progress despite discontinuation
of PTU. Recognition of the need for liver transplantation and prompt
referral to a transplant center may be lifesaving. Using these combined
approaches it is possible that deaths from PTU-associated
hepatotoxicity might be reduced over the next 50 years.
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| Acknowledgments |
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| Footnotes |
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Received September 18, 1996.
Revised December 12, 1996.
Accepted January 26, 1997.
| References |
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