Factors affecting drug-induced liver injury: antithyroid drugs as instances

Research progress on rodent models and its mechanisms of liver injury

The liver is the most important organ for biological transformation in the body and is crucial for maintaining the body's vital activities. Liver injury is a serious pathological condition that is commonly found in many liver diseases. It has a high incidence rate, is difficult to cure, and is prone to recurrence. Liver injury can cause serious harm to the body, ranging from mild to severe fatty liver disease. If the condition continues to worsen, it can lead to liver fibrosis and cirrhosis, ultimately resulting in liver failure or liver cancer, which can seriously endanger human life and health. Therefore, establishing an rodent model that mimics the pathogenesis and severity of clinical liver injury is of great significance for better understanding the pathogenesis of liver injury patients and developing more effective clinical treatment methods. The author of this article summarizes common chemical liver injury models, immune liver injury models, alcoholic liver injury models, drug-induced liver injury models, and systematically elaborates on the modeling methods, mechanisms of action, pathways of action, and advantages or disadvantages of each type of model. The aim of this study is to establish reliable rodent models for researchers to use in exploring anti-liver injury and hepatoprotective drugs. By creating more accurate theoretical frameworks, we hope to provide new insights into the treatment of clinical liver injury diseases.

Clinical Characteristics and Outcomes of Patients With Antithyroid Drug-Related Liver Injury

Context

Antithyroid drugs (ATDs) are the cornerstone of hyperthyroidism management. Hepatotoxicity due to ATDs can range from mild transaminase elevation to liver transplantation requirement and mortality.

Objective

The primary objective of the systematic review was to assess the clinical characteristics and outcomes of patients with drug induced liver injury (DILI) due to ATDs.

Methods

We conducted a systematic review of PUBMED, SCOPUS, and EMBASE on characteristics and outcomes of adults (>18 years) with DILI due to ATDs. We defined DILI as bilirubin ≥2.5 mg/dL or international normalized ratio >1.5 with any rise in alanine aminotransferase (ALT), aminotransferase (AST), or alkaline phosphatase (ALP), or an elevation of ALT or AST >5 times or ALP >2 times the upper limit of normal without jaundice/coagulopathy.

Results

The review included 100 articles describing 271 patients; 148 (70.8%) were female (N = 209). Mean age was 42.9 ± 17.2 years. Graves' disease was the most common indication for ATDs. Carbimazole/methimazole (CBM/MMI) was the most common offending agent (55.7%). DILI pattern was hepatocellular in 41.8%, cholestatic in 41.3%, and mixed in 16.9%. Outcomes included death in 11.8%, liver transplantation in 6.4%, partial improvement in 2.2%, and complete resolution in 79.6% with a median time (IQR) to resolution of 45 (20-90) days. Patients in the propylthiouracil (PTU) group had higher initial bilirubin, initial AST, initial ALT, peak ALT, peak AST, severe and fatal DILI, liver transplantation, and mortality than CBM/MMI. Rechallenge of antithyroid medication was infrequently reported (n = 16) but was successful in 75%.

Conclusion

DILI due to ATDs can present with different patterns and should prompt immediate drug discontinuation. Referral to a hepatologist should be considered if severe as transplantation is sometimes required. PTU-induced DILI may have worse outcomes than CBM/MMI.

Case report: Severe cholestatic jaundice associated with hyperthyroidism treated with methimazole

RATIONALE

We present a case of a 43-year-old female patient diagnosed with hyperthyroidism. This study aims to demonstrate the rare association between hyperthyroidism and severe cholestatic jaundice, and the effectiveness of methimazole treatment.

PATIENT CONCERNS

The patient developed severe jaundice, a typically mild symptom in most hyperthyroidism cases.

DIAGNOSIS

The severe jaundice was suspected to be a result of cholestasis induced by hyperthyroidism, with other potential causes such as drug-induced or autoimmune liver dysfunction being ruled out.

OUTCOMES

The patient was effectively treated with methimazole. Outcomes: Treatment with methimazole alleviated the severe cholestatic jaundice and restored normal thyroid function.

LESSONS

The specific mechanism of cholestasis as a secondary complication of hyperthyroidism remains unclear, and there are no specific biochemical markers for cholestasis caused by this hormonal disease. This case underscores the possibility of severe jaundice as a clinical manifestation of hyperthyroidism, and highlights antithyroid drug treatment as an effective strategy for managing severe cholestatic jaundice.

Vitamin D alleviates hypothyroidism associated liver dysfunction: Histological and biochemical evidence

There is a complex correlation between thyroid hormones (THs) and liver function. Hypothyroidism as a failure of the thyroid gland to produce adequate thyroid hormones to fulfill the metabolic requirements of the body, may perturb liver structure and function. Emerging evidence suggests the protective effects of vitamin D against liver damage. Herein, this study aimed to investigate the role of vitamin D in hypothyroidism-associated liver injury. Forty male Wistar rats were classified into 4 groups: control, hypothyroid (Hypo) group received 0.05% PTU, Hypo- Vitamin D groups were given 100 and 500 IU/kg vitamin D orally via gavage for 6 weeks. Serum level of liver function including alanine aminotransferase (ALT), aspartate aminotransferase (AST), and alkaline phosphatase (ALP) were measured. Malondialdehyde (MDA) level, superoxide dismutase (SOD) enzyme activity, and total thiol content were measured as oxidative stress indicators in the liver tissue. Furthermore, to estimate liver tissue fibrosis, Masson's trichrome staining was done. Our findings showed that hypothyroidism-induced liver fibrosis was associated with increased levels of ALT, AST and ALP. Though, vitamin D administration could significantly reduce the ALT, AST and ALP in the serum and suppress the accumulation of collagen fibers. Moreover, the activity of SOD and total thiol content was notably reduced, while the MDA content was significantly increased in the PTU- induced hypothyroid rats compared to the control group. Nonetheless, treatment with vitamin D improved mentioned oxidative stress markers in the Hypo-vitamin D groups. In conclusion, vitamin D due to its potential antioxidant and anti-fibrotic properties could be effective in the decrease of hypothyroidism-associated liver injury.

Approach to the Patient: Management and the Long-term Consequences of Graves' Disease in Children

In children, Graves' disease (GD) is the most common cause of hyperthyroidism. Most pediatric patients with GD will not go into lasting remission, even following many years of antidrug therapy. Thus, most pediatric patients will require radioactive iodine (RAI) or surgery. When antithyroid drugs are used, methimazole is the drug of choice. When methimazole is used in children, up to 20% will have minor adverse reactions and serious adverse events occur in up to 1%. RAI is an effective form of therapy when the thyroid size is less than 80 g. Because of concerns of whole-body radiation exposure, it is recommended that RAI be avoided in children under 5 years of age, and dosages less than 10 mCi be used between 5 and 10 years of age. Surgery is an effective treatment in children if performed by a high-volume thyroid surgeon. Because of the scarcity of high-volume pediatric thyroid surgeons, a multidisciplinary approach using pediatric surgeons and endocrine surgeons can be considered. Whereas there is a trend toward long-term antithyroid drug therapy in adults, for several reasons, this approach may not be practical for children. Determining the optimal treatment for the pediatric patient with GD, requires consideration of the risks and benefits relating to age and likelihood of remission.

Protective Effect of Natural Antioxidant Compounds on Methimazole Induced Oxidative Stress in a Feline Kidney Epithelial Cell Line (CRFK)

The treatment of choice for feline hyperthyroidism is the administration of the antithyroid drug methimazole. Both the endocrinopathy and the drug adverse reactions (e.g., hepatotoxicosis, gastrointestinal disorders, and renal injury) are partly due to oxidative stress and redox unbalance. This study investigated the free radical production and the impairment of the antioxidant barrier induced by methimazole in an in vitro model of feline renal epithelium. The protective effects of quercetin and resveratrol were also explored. CRFK cells were incubated with a methimazole concentration equivalent to the maximum plasma levels in orally treated cats (4 µM), in the presence or absence of either one of the two selected antioxidants at different time-points (up to 72 h). Cell viability, ROS production, GSH levels, and mRNA expression of antioxidant enzymes (i.e., CAT, SOD, GPx, and GST) were assessed. Methimazole impaired cell viability and increased ROS levels in a time-dependent manner. Similarly, GSH content and CAT, SOD, and GPx3 expression were higher compared with control cells. Such effects were significantly counteracted by quercetin. These results provide new insights about the mechanisms underlying the methimazole-related side effects frequently observed in hyperthyroid cats. They also support the use of quercetin in the management of feline hyperthyroidism.

Management of Feline Hyperthyroidism and the Need to Prevent Oxidative Stress: What Can We Learn from Human Research?

Feline hyperthyroidism is a clinical syndrome related to an excessive production of thyroid hormones, and it is considered as a spontaneous animal model for human thyrotoxicosis. Many shared features between the feline and the human disease have been identified so far, including pathogenesis, clinical signs, and treatment options. Although methimazole is considered the first-choice drug in both species, several side effects have been described. Furthermore, methimazole could interfere with the oxidative status, already perturbated by the disease. It has been reported in humans that dietary management, mainly through antioxidant supplementation, could mitigate this oxidative burden. The purpose of the review is to describe current therapeutic options in the course of feline hyperthyroidism and to summarize the state of the art relationship between dietary antioxidants administration and the reduction of methimazole side-effects in humans to support the use of this approach also in cats.

Comparison of long-term antithyroid drugs versus radioactive iodine or surgery for Graves' disease: A review of the literature

BACKGROUND

The management of Graves' disease (GD) in the US is shifting towards increased use of anti-thyroid drugs (ATD). If patients fail to achieve remission after a standard course of therapy of 12-18 months, long-term treatment with ATD (≥24 months) may be chosen over definitive therapy with radioiodine (RAI) or surgery. Clinicians will need to contrast this strategy to ablative therapies as they help patients in decision making.

SUMMARY

Review of the literature illustrates that long-term ATD delivers euthyroidism with minimal complications, low financial cost and with an advantageous profile regarding quality of life (QoL) and other biological outcomes.

CONCLUSIONS

Long-term ATD is a viable alternative to ablative therapies in the management of GD offering advantages across multiple patient centred outcomes. Decision making must factor differences in this approach compared to ablative therapies and ultimately be tailored to individualized patient situations.

[The thyroid gland in old age : Physiology and pathology]

In healthy older people the metabolism of thyroid hormones is physiologically altered and can possibly even actively contribute to longevity. This should also be taken into consideration in the treatment of diseases of the thyroid and principally also for younger patients. For example, with progressing age comorbidities become more prevalent and especially in cardiovascular diseases, hyperthyroidism is less well tolerated, and should be treated more aggressively. Benign multinodular goiter also becomes more prevalent in old age and should be surgically treated when causing mechanical symptoms. The treatment concept for malignant diseases should be adapted to the holistic situation of the patient but principally in the same manner as in younger patients. Old and very old patients also benefit from adequate, risk-adapted treatment of thyroid gland diseases so that appropriate diagnostics and clarification are meaningful, regardless of age.

MATERNAL GRAVES DISEASE AND ABNORMAL CYP2D6 GENOTYPE WITH FETAL HYPERTHYROIDISM

Objective

Fetal hyperthyroidism is a rare yet potentially fatal complication of past or present maternal Graves disease (GD). Our objective was to present a unique case of fetal hyperthyroidism in a mother with a prior history of GD and a cytochrome P450 2D6 (CYP2D6) polymorphism.

Methods

The clinical course in addition to serial laboratory and imaging results are presented. These include thyroid-stimulating hormone, free thyroxine, and thyrotropin receptor antibody levels, as well as fetal ultrasound, doppler fetal heart rate, and cordocentesis testing.

Results

A 27-year-old with a history of GD previously treated with radioiodine and a known cytochrome P450 polymorphism was referred to an endocrinology clinic at 17 weeks gestation for evaluation and management of fetal thyrotoxicosis. Despite close follow-up with a multidisciplinary care team and an aggressive "block and replace" treatment approach, progressive disease resulted in intrauterine fetal demise at 28 weeks gestation.

Conclusion

To our knowledge, this is the first published case report of fetal hyperthyroidism accompanied by a maternal CYP2D6 polymorphism. We hypothesize that the maternal CYP2D6 poor metabolizer phenotype prevents formation of antithyroid drug (ATD) metabolites and thus decreases the efficacy of ATD treatment. We suggest this as an area of future research.

Evaluation of Antioxidant Supplementation on Redox Unbalance in Hyperthyroid Cats Treated with Methimazole: A Blinded Randomized Controlled Trial

Methimazole (MMI) is often the selected medical treatment for feline hyperthyroidism. However, the onset of MMI-related side effects (MMI-SE) is likely caused by oxidative stress. This study evaluated the dietary supplementation of selected antioxidants in hyperthyroid cats receiving MMI, to reduce MMI-SE. Thirty hyperthyroid client-owned cats were randomly allocated in group M (MMI + placebo) or group M+A (MMI + antioxidants). At different time-points from the enrolment (ET) to the end of the trial (FT), the following information was recorded: clinical findings, complete blood count, serum biochemical parameters, urinalysis, total plasma thyroxine concentrations, determinable reactive oxygen metabolites (dROMs), OXY-adsorbent test values, and oxidative stress index (OSi) values, and MMI-SE. dROMs and OSi values significantly increased from ET to FT in group M and were significantly higher in group M than in group M+A at FT. Likewise, OXY-absorbent test values were significantly higher in group M+A than in group M at FT. Moreover, the occurrence rate of MMI-SE in group M+A was lower than in group M. In conclusion, our results show that the dietary supplementation of antioxidants in hyperthyroid cats receiving MMI exerts a protective effect against oxidative stress, likely contributing to the reduction of MMI-SE.

Association between genetic polymorphisms of SLCO1B1 and susceptibility to methimazole-induced liver injury

Methimazole (MMI) has been used in the therapy of Grave's disease (GD) since 1954, and drug-induced liver injury (DILI) is one of the most deleterious side effects. Genetic polymorphisms of drug-metabolizing enzymes and drug transporters have been associated with drug-induced hepatotoxicity in many cases. The aim of this study was to investigate genetic susceptibility of the drug-metabolizing enzymes and drug transporters to the MMI-DILI. A total of 44 GD patients with MMI-DILI and 118 GD patients without MMI-DILI development were included in the study. Thirty-three single nucleotide polymorphisms (SNPs) in twenty candidate genes were genotyped. We found that rs12422149 of SLCO2B1, rs2032582_AT of ABCB1, rs2306283 of SLCO1B1 and rs4148323 of UGT1A1 exhibited a significant association with MMI-DILI; however, no significant difference existed after Bonferroni correction. Haplotype analysis showed that the frequency of SLCO1B1*1a (388A521T) was significantly higher in MMI-DILI cases than that in the control group (OR = 2.21, 95% CI = 1.11-4.39, P = 0.023), while the frequency of SLCO1B1*1b (388G521T) was significantly higher in the control group (OR = 0.52, 95% CI = 0.29-0.93, P = 0.028). These results suggested that genetic polymorphisms of SLCO1B1 were associated with susceptibility to MMI-DILI. The genetic polymorphism of SLCO1B1 may be important predisposing factors for MMI-induced hepatotoxicity.

Redox unbalance in the hyperthyroid cat: a comparison with healthy and non-thyroidal diseased cats

Background

Feline hyperthyroidism, the most common endocrinopathy in older cats, provides a spontaneous model for human thyrotoxicosis. Human thyrotoxicosis is associated with redox unbalance, which may result in organ damage. The redox status of hyperthyroid cats is largely unknown. The aims of the present study were to compare the redox status of cats with hyperthyroidism with that of healthy cats and cats with chronic non-thyroidal illness.

Results

Forty cats with untreated hyperthyroidism (group H), 45 chronically ill cats with non-thyroidal illness (group I), and 39 healthy cats (group C) were recruited for this observational cross-sectional study. All cats were screened for redox status markers. Determinable reactive oxygen metabolites (d-ROMs) were used as oxidative stress markers. Antioxidant status was determined using the OXY-Adsorbent test to quantify the plasma barrier to oxidation. The Oxidative Stress index (OSi) was calculated as the ratio of d-ROMs and OXY-Adsorbent test values. Data were compared by ANOVA with Tukey’s multiple comparisons post-hoc test. The dROMs of group H (193 ± 47 CarrU) were significantly higher (p < 0.001) than those of the healthy cats (103 ± 17 CarrU). The OXY-Adsorbent test results in group H (265 ± 68 μmol HClO/ml) were significantly lower than those in healthy cats (390 ± 83 μmol HClO/ml; p < 0.01) and chronically ill cats (306 ± 45 μmol HClO/ml, p < 0.05). Moreover, the Osi value in group H (0.8 ± 0.2 CarrU/μmol HClO/ml) was significantly higher (p < 0.001) than that of the healthy cats (0.3 ± 0.1 CarrU/μmol HClO/ml).

Conclusions

As described in humans with hyperthyroidism, feline hyperthyroidism is associated with redox unbalance. Free radical production is increased in hyperthyroid cats and their antioxidant depletion seems to be more severe than in cats with non-thyroidal illnesses. Our results support the rationale for a clinical trial investigating the potential positive effects of antioxidant supplementation to cats with hyperthyroidism.

Electronic supplementary material

The online version of this article (10.1186/s12917-019-1896-7) contains supplementary material, which is available to authorized users.

Research Progress on the Animal Models of Drug-Induced Liver Injury: Current Status and Further Perspectives

Drug-induced liver injury (DILI) is a major concern in clinical studies as well as in postmarketing surveillance. It is necessary to establish an animal model of DILI for thorough investigation of mechanisms of DILI and searching for protective medications. This article reviews the current status and future perspective on establishment of DILI models based on different hepatotoxic drugs, as well as the underlying mechanisms of liver function damage induced by specific medicine. Therefore, information from this article can help researchers make a suitable selection of animal models for further study.

Boldine Supplementation Regulates Mitochondrial Function and Oxidative Stress in a Rat Model of Hepatotoxicity

Background: The xenobiotics-induced liver injury is a clinical complication. Hence, finding new hepatoprotective strategies has clinical value. Oxidative stress and its subsequent complications are major mechanisms involved in xenobiotics-induced hepatotoxicity. Boldine is one of the most potent antioxidant molecules widely investigated for its protective properties in different experimental models. In the current study, the hepatoprotective properties of boldine and its potential mechanisms of hepatoprotection have been investigated. Methods: Rats received thioacetamide (TAA; 200 mg/kg, i.p) as a model of acute liver injury. Boldine (5, 10, 1nd 20 mg/kg; 24 hours intervals; oral) was administered as the hepatoprotective agent. Results: Liver injury was evident in TAA-treated animals (48 hours after TAA exposure) as a severe increase in serum level of liver injury biomarkers and histopathological alterations. Moreover, markers of oxidative stress were increased in liver tissue of TAA-treated rats. Assessment of mitochondrial indices of functionality revealed a significant decrease in mitochondrial dehydrogenases activity, the collapse of mitochondrial membrane potential, mitochondrial swelling and depletion of ATP content. It was found that boldine supplementation mitigated liver tissue markers of oxidative stress and improved mitochondrial indices of functionality in TAA-treated animals. Conclusion: The hepatoprotective properties of boldine might primarily rely on antioxidant and mitochondria protecting effects of this alkaloid.

Low-expressional IGF1 mediated methimazole-induced liver developmental toxicity in fetal mice

Anti-thyroid drugs (ATDs) therapy is necessary for pregnant women with hyperthyroidism. However, there is a lack of studies on developmental toxicity of ATDs. In this study, we observed the developmental toxicity of fetal liver induced by prenatal methimazole exposure (PME) in mice, and explored the potential mechanism. Pregnant Kunming mice were administered intragastrically with 4.5 or 18 mg/kg·d methimazole from gestational day (GD) 9∼18. After PME, the birth weights of the offspring mice were decreased, and the liver morphology, development indexes and metabolic function were all altered in different degree in the PME fetuses. Meanwhile, PME decreased the levels of serum and hepatic insulin-like growth factor 1 (IGF1), and reduced the gene expression of IGF1 downstream signaling pathway. Furthermore, the protein levels of phosphorylated-extracellular regulated protein kinases (p-ERK) and serine-threonine protein kinase (p-Akt) were also reduced. Furthermore, methimazole disturb hepatocyte differentiation, maturation and metabolic function through suppressing IGF1 signaling pathway in HepG2 cells. These results demonstrated that PME could induce fetal liver developmental toxicity, and the underlying mechanism was related to low-expression of hepatic IGF1 caused by methimazole, which mediated abnormal liver morphology and metabolic function.

Exacerbated liver injury of antithyroid drugs in endotoxin-treated mice

Drug-induced liver injury is a major concern in clinical studies as well as in post-marketing surveillance. Previous evidence suggested that drug exposure during periods of inflammation could increase an individual's susceptibility to drug hepatoxicity. The antithyroid drugs, methimazole (MMI) and propylthiouracil (PTU) can cause adverse reactions in patients, with liver as a usual target. We tested the hypothesis that MMI and PTU could be rendered hepatotoxic in animals undergoing a modest inflammation. Mice were treated with a nonhepatotoxic dose of LPS (100 µg/kg, i.p) or its vehicle. Nonhepatotoxic doses of MMI (10, 25 and 50 mg/kg, oral) and PTU (10, 25 and 50 mg/kg, oral) were administered two hours after LPS treatment. It was found that liver injury was evident only in animals received both drug and LPS, as estimated by increases in serum alanine aminotransferase (ALT), lactate dehydrogenase (LDH), aspartate aminotransferase (AST), and TNF-α. An increase in liver myeloperoxidase (MPO) enzyme activity and tissue lipid peroxidation (LPO) in addition of liver glutathione (GSH) depletion were also detected in LPS and antithyroid drugs cotreated animals. Furthermore, histopathological changes including, endotheliitis, fatty changes, severe inflammatory cells infiltration (hepatitis) and sinusoidal congestion were detected in liver tissue. Methyl palmitate (2 g/kg, i.v, 44 hours before LPS), as a macrophage suppressor, significantly alleviated antithyroids hepatotoxicity in LPS-treated animals. The results indicate a synergistic liver injury from antithyroid drugs and bacterial lipopolysaccharide coexposure.

Effect of Goiter Dispersion Formula on Serum Cytokines in Hyperthyroidism Patients with Neurologic Manifestations of Graves' Disease: A Randomized Trial on 80 Cases

PURPOSE

This study is aimed to explore the combined use of goiter dispersion formula and antithyroid drugs in the treatment of patients with neurologic manifestations of Graves' disease by examining its modulating effects on patients' cytokines.

METHODS

A total of 80 patients with Graves' disease were randomly divided into treatment and control groups. Patients of the treatment group received goiter dispersion formula and antithyroid drugs (methimazole or propylthiouracil), whereas those of the control group received antithyroid drug alone. FT3, FT4, and TSH contents were detected by chemiluminescence immunoassay at pre- and post-treatment; interleukin (IL)-2, IL-8, and IL-17 serum levels before and after the treatment were detected by radioimmunoassay; thyroid B-mode ultrasound and liver and renal function tests were performed in all patients of both groups. An additional cohort of 40 healthy subjects was recruited for baseline measurement.

RESULTS

All the enrolled patients completed the trial. The effective treatment rate was higher in the treatment group than in the control group, of which the difference was statistically significant (treatment group, 95%; control group, 75%, p < 0.01). For blood cytokine, before treatment, IL-2 was reduced whereas IL-8 and IL-17 were increased significantly in both groups of patients with Graves' disease comparing with those in healthy subjects (p < 0.01). For patients of the treatment group, after treatment, their IL-2 levels were increased (p < 0.01) with concomitant decreases in IL-8 and IL-17 levels (p < 0.05). There were no significant changes in blood cytokine levels before and after treatment in the control group.

CONCLUSIONS

Goiter dispersion formula significantly improved the treatment outcomes of antithyroid drug in hyperthyroidism patients with neurologic manifestations of Graves' disease by modulating IL-2, IL-8, and IL-17. The data supported the rationale for the use of goiter dispersion formula in Graves' disease treatment.

Impact of cell types and culture methods on the functionality of in vitro liver systems - A review of cell systems for hepatotoxicity assessment

Xenobiotic safety assessment is an area that impacts a multitude of different industry sectors such as medicinal drugs, agrochemicals, industrial chemicals, cosmetics and environmental contaminants. As such there are a number of well-developed in vitro, in vivo and in silico approaches to evaluate their properties and potential impact on the environment and to humans. Additionally, there is the continual investment in multidisciplinary scientists to explore non-animal surrogate technologies to predict specific toxicological outcomes and to improve our understanding of the biological processes regarding the toxic potential of xenobiotics. Here we provide a concise, critical evaluation of a number of in vitro systems utilised to assess the hepatotoxic potential of xenobiotics.

Hepatotoxicity in hyperthyroid patient after consecutive methimazole and propylthiouracil therapies

Methimazole (MMI) and propylthiouracil (PTU) are widely used antithyroid drugs (ATD) that have been approved for the treatment of hyperthyroidism. Hepatotoxicity may be induced by these drugs, though they exert dissimilar incidence rates of hepatotoxicity and, possibly, with different underlying pathogenic mechanisms. We report the case of a 55-year-old woman with no relevant medical history diagnosed with hyperthyroidism due to Graves' disease, who developed two episodes of acute hepatitis concurrent with the consecutive administration of two different ATDs, first MMI and then PTU. Given the impossibility of administering ATDs, it was decided to perform a total thyroidectomy because the patient was found to be euthyroid at that point. Pathological anatomy showed diffuse hyperplasia and a papillary thyroid microcarcinoma of 2 mm in diameter. Subsequent clinical check-ups were normal. This case suggests the importance of regular monitoring of liver function for hyperthyroid patients. Due to the potential severity of this side effect, it is recommended to determine baseline liver function prior to initiation of treatment.

LEARNING POINTS

We present a rare case of two acute hepatitis episodes concurrent with two different consecutive ATD therapies.Our results highlight the relevance of a liver function monitoring during the treatment with MMI or PTU.A baseline assessment of the liver function before starting an ATD treatment should be recommendable.

Methimazole-induced liver injury overshadowed by methylprednisolone pulse therapy: Case report

RATIONALE

Treatment choices are limited, when deciding how to manage thyrotoxicosis and moderate to severe Graves ophthalmopathy (GO) with suspected optic nerve damage in patients with elevated liver transaminase levels. The situation become even more complicated, if methimazole induced hepatotoxicity is suspected and intravenous methylprednisolone is co-administrated.

PATIENT CONCERNS

A 74-year-old woman presented with spontaneous retro-bulbar pain, eyelid swelling and inconstant diplopia.

DIAGNOSES

Thyrotoxicosis and severe GO with suspected optic nerve damage and drug induced liver injury (DILI).

INTERVENTIONS

Intravenous methylprednisolone pulse therapy was administered to treat GO and methimazole was continued for thyrotoxicosis. Dose of methimazole was reduced after exclusion of concurrent infection and active liver disease.

OUTCOMES

The GO symptoms (eyelid swelling, sight loss, proptosis, retro-bulbar pain, diplopia) markedly decreased after the treatment course. Liver transaminases spontaneously returned to normal ranges and remained normal during the next 12 months until the Graves' disease until the treatment was completed.

LESSONS

1. The interaction of methimazole and methylprednisolone may result in DILI. 2. In a patient without concomitant liver diseases MP can be continued if the methimazole dose is reduced if no other treatment options are available.

Incidence of abnormal liver biochemical tests in hyperthyroidism

OBJECTIVE

Abnormal serum liver function tests are common in patients with untreated thyrotoxicosis, even prior to the initiation of antithyroidal medications that may worsen the severity of the abnormal serum liver biochemistries. There is a wide range of the incidence of these abnormalities in the published literature. The aim of this study was to assess the risks factors and threshold of thyrotoxicosis severity for developing an abnormal liver biochemical test upon the diagnosis of new thyrotoxicosis.

DESIGN

Single-institution retrospective cohort study.

PATIENTS

Patients of ≥18 years old receiving medical care at a large, academic, urban US medical centre between 2002-2016.

MEASUREMENTS

Inclusion criteria were a serum thyroid stimulating hormone (TSH) concentration of <0·3 mIU/l or ICD-9 code for thyrotoxicosis, with thyrotoxicosis confirmed by either a concurrent elevated serum triiodothyronine (T3) or thyroxine (T4) concentration ([total or free] within 3 months), and an available liver biochemical test(s) within 6 months of thyrotoxicosis. The biochemical liver tests assessed were serum aspartate transaminotransferase (AST), alanine aminotransferase (ALT), alkaline phosphatase (AP), gamma-glutamyltransferase (GGT), total bilirubin, and conjugated bilirubin concentrations.

RESULTS

In this cohort of 1514 subjects, the overall incidence of any biochemical liver test abnormality within 6 months of thyrotoxicosis was 39%. An initial serum TSH concentration <0·02 mIU/l, male gender, and African-American race were significant predictors of an abnormal serum liver biochemical test within 6 months of the diagnosis of new-onset untreated thyrotoxicosis.

CONCLUSIONS

This study identifies risk factors for patients who develop an abnormal serum liver biochemical test result within 6 months of a diagnosis of untreated thyrotoxicosis.

The Opportunities of Metabolomics in Drug Safety Evaluation

Although safety of drug candidates is carefully monitored in preclinical and clinical studies using a variety of approaches, drug toxicity may still occur in clinical practice. Therefore, novel approaches are needed to complement the current drug safety evaluation system. Metabolomics comprehensively analyzes the metabolites altered by drug exposure, which can therefore be used to profile drug metabolism, endobiotic metabolism, and drug-microbiota interactions. The information from metabolomic analysis can be used to determine the off-targets of a drug candidate, and thus provide a mechanistic understanding of drug toxicity. We herein discuss the opportunities of metabolomics in drug safety evaluation.

Gruchy S, MacLeod M. Ramipril-associated cholestasis in the setting of recurrent drug-induced liver injury

Aim: Angiotensin-converting enzyme inhibitors (ACEIs) are commonly used to treat hypertension. Although generally well tolerated, the adverse effects of ACEIs include hypotension, cough, acute kidney injury and hyperkalemia. Rare reports of ACEI-induced hepatotoxicity have been described, most notably a cholestatic pattern of injury related to captopril. A 67-year-old male presented to the emergency department with a three-week history of jaundice, pruritis and weakness. Eight weeks before, he began taking ramipril and clopidogrel. His past medical history was significant for previous acute cholestatic liver injury approximately 20 years earlier, which was attributed to methimazole. Abnormal blood work demonstrated aspartate aminotransferase (AST) 47 U/L, alanine aminotransferase (ALT) 46 U/L, total bilirubin 230 µmol/L, direct bilirubin 176 µmol/L, and alkaline phosphatase (ALP) 470 U/L. Abdominal ultrasound and magnetic resonance cholangiopancreatography showed no bile duct obstruction. Further work-up was negative for infectious, autoimmune, or other causes. Percutaneous liver biopsy showed marked cholestasis. With discontinuation of ramipril, the patient demonstrated prolonged cholestasis with partial biochemical improvement and was discharged after six weeks in hospital. This case represents the first described cross reactivity between ramipril and methimazole, illustrating the complex and poorly understood nature of DILI. Despite the relatively few instances of ACEI-induced liver hepatotoxicity, consideration should be given to discontinuation of ramipril in situations of unknown liver damage.

Drug-induced liver injury caused by iodine-131

Iodine-131 is a radioisotope that is routinely used for the treatment of differentiated thyroid cancer after total or near-total thyroidectomy. However, there is some evidence that iodine-131 can induce liver injury . Here we report a rare case of drug-induced liver injury (DILI) caused by iodine-131 in a patient with regional lymph node metastasis after total thyroidectomy. A 47-year-old woman was admitted with elevated liver enzymes and symptoms of general weakness and nausea. Ten weeks earlier she had undergone a total thyroidectomy for papillary thyroid carcinoma and had subsequently been prescribed levothyroxine to reduce the level of thyroid-stimulating hormone. Eight weeks after surgery she underwent iodine-131 ablative therapy at a dose of 100 millicuries, and subsequently presented with acute hepatitis after 10 days. To rule out all possible causative factors, abdominal ultrasonography, endoscopic ultrasonography (on the biliary tree and gall bladder), and a liver biopsy were performed. DILI caused by iodine-131 was suspected. Oral prednisolone was started at 30 mg/day, to which the patient responded well.

Effect of Thiol-reducing Agents and Antioxidants on Sulfasalazine-induced Hepatic Injury in Normotermic Recirculating Isolated Perfused Rat Liver

Sulfasalzine is a widely administered drug against inflammatory-based disorders in human. However several cases of liver injury are associated with its administration. There is no stabilized safe protective agent against sulfasalazine-induced liver injury. Current investigation was designed to evaluate if N-acetylcysteine (NAC) and dithioteritol (DTT) as thiol reducing agents and/or vitamins C and E as antioxidants have any protective effects against sulfasalazine-induced hepatic injury in an ex vivo model of isolated rat liver. Rat liver was canulated and perfused via portal vein in a closed recirculating system. Different concentrations of sulfasalazine and/or thiol reductants and antioxidants were administered and markers of organ injury were monitored at different time intervals. It was found that 5 mM of sulfasalazine caused marked liver injury as judged by rise in liver perfusate level of alanine aminotransferase (ALT), aspartate aminotransferase (AST), and lactate dehydrogenase (LDH) (p < 0.05). A significant amount of lipid peroxidation and hepatic glutathione depletion were detected in drug-treated livers, accompanied with significant histopathological changes of the organ. Administration of NAC (500 μM), DTT (400 μM), Vitamin C (200 μM), or vitamin E (200 μM) significantly alleviated sulfasalazine-induced hepatic injury in isolated perfused rat liver. The data obtained from current investigation indicate potential therapeutic properties of thiol reductants and antioxidants against sulfasalazine-induced liver injury.

Hyperthyroidism Improves the Pathological Condition of Nonalcoholic Steatohepatitis: A Case of Nonalcoholic Steatohepatitis with Graves' Disease

3,5,3'-triiodo-L-thyronine regulates the glucose metabolism, lipid metabolism, and hepatic steatosis. Several groups have shown the relationships between hypothyroidism and nonalcoholic fatty liver and hypothyroidism and nonalcoholic steatohepatitis (NASH). However, the effect of hyperthyroidism on NASH has not yet been investigated. We herein report effects of thyroid hormone on the pathological condition of NASH in a patient with NASH complicated by Graves' disease. In our case, the liver enzyme level improved with the increasing thyroid hormone level; however, the liver enzyme level was aggravated with the improving thyroid hormone level. Therefore, hyperthyroidism may improve the pathological condition of NASH.

Factors predicting abnormal liver function tests induced by Graves' disease alone: a retrospective cohort study

Abnormal liver function tests (LFTs) are often observed in patients with Graves' disease (GD). To date, there are limited data demonstrating the factors or biochemical indexes contributing to LFT abnormalities in this patient population. The aim of this study was to explore factors predicting abnormal LFTs induced by GD alone. This was a retrospective study of 289 consecutive cases of newly diagnosed and untreated patients with GD. All patients were divided into abnormal LFTs (group A) and normal LFTs (group B). In total, 205 (70.9%) cases were found to have at least 1 LFT abnormality. Among them, the frequencies of ALT, AST, ALP, γ-GTP, TBIL and DBIL abnormalities were 52.7%, 32.2%, 45.9%, 38.5%, 23.4%, 2.9%, respectively, and the number of patients with 1 to 6 hepatic variable abnormalities were 89, 64, 30, 16, 6 and 0, respectively. Logistic regression analysis was used to determine predictive factors contributing to abnormal LFTs. A receiver operating characteristic (ROC) curve was also plotted to verify the accuracy of predictors. In the univariate analysis, patients in group A had significantly higher FT3 concentration (37.5 vs 33.4 pmol/L, P = 0.009), FT4 concentration (85.7 vs 77.4 pmol/L, P = 0.002) and TRAb level (22.2 vs 17.4 IU/L, P < 0.001) when compared with those in group B. Binary logistic regression analysis identified higher FT4 concentration (odds ratio [OR]: 1.017, 95% confidence interval [CI]: 1.005-1.030, P = 0.006) and higher TRAb value (OR: 1.038, 95% CI:1.013-1.064, P = 0.003) to be independent risk factors predicting abnormal LFTs. The optimal cutoffs for FT4 and TRAb to predict abnormal LFTs were 75 pmol/L and 15 IU/L, respectively, based on ROC analysis.