Elevated thyroxine levels due to increased thyroxine-binding globulin in acute hepatitis

Fulminant liver failure associated with delayed identification of thyroid storm due to heterophile antibodies

Hepatic dysfunction during hyperthyroidism frequently occurs with mild abnormalities in liver function tests that are self-limited, improving after treatment of thyroid disease. With the exception of congestive heart failure or secondary hepatic disease, significant hepatic compromise during thyrotoxicosis is rare and often of unexplained origin. This report identifies a novel case of severe hepatic compromise in the setting of thyrotoxicosis that was not initially identified due to a falsely elevated TSH. A 43-year-old African-American man presented to the intensive care unit with severe jaundice, weight loss, thyroid bruit and altered mental status. Initial diagnosis of hyperthyroidism was delayed due to a non-suppressed TSH of 0.20 μU/mL. Laboratory studies identified dramatic hepatic synthetic dysfunction and elevated transaminases with a total bilirubin of 47.4 mg/dL, AST 259 U/L, and ALT 142 U/L. No toxins, structural or viral causes of liver disease were identified and the patient was prepared for potential liver biopsy. Heterophile antibodies were identified and removed by precipitation, demonstrating an undetectable TSH and free thyroxine 9.0 ng/dL consistent with hyperthyroidism. Subsequent treatment with thionamides, corticosteroids, and potassium iodide improved both thyroid and liver function and avoided unnecessary invasive testing. Heterophile antibodies remain as important interfering factors in TSH immunoassays, and thus, this case demonstrates the importance of matching the clinical picture with available laboratory data. In the absence of a known cause of hepatic dysfunction, hyperthyroidism should be considered as a potential etiology of acute liver failure of unknown origin.

Spurious t3 thyrotoxicosis unmasking multiple myeloma

Objective. To document a case of spurious T3 thyrotoxicosis in a 54-year-old woman. Methods. We present the diagnostic approach of a patient with euthyroid hypertri-iodothyronemia. Results. A 54-year-old, clinically euthyroid woman without personal or family history of thyroid disease referred to endocrinology for possible T3 thyrotoxicosis, after thyroid function tests revealed total T3 > 800 ng/dL (reference range 60-181), normal TSH, and T4. The laboratory data were not compatible with the clinical picture, so thyroid binding globulin abnormalities were suspected. Additional laboratory studies confirmed the diagnosis of multiple myeloma. Conclusion. Monoclonal gammopathy is characterized by the presence of a monoclonal immunoglobulin in the serum or urine, occurring in multiple myeloma, and can cause assay interference and spurious results. We identify a newly recognized cause of euthyroid hypertri-iodothyronemia, due to binding of T3 to monoclonal immunoglobulins in the setting of multiple myeloma. Our case is the only one to date suggesting that monoclonal immunoglobulins from multiple myeloma may exhibit binding to T3 only.

Thyroid hormone levels in children with liver cirrhosis awaiting a liver transplant

OBJECTIVES

Evidence exists that decreased in triiodothyronine (T3) and thyroxine (T4) levels are associated with the severity of liver disease, and these hormones could be used as disease prognostic factors, but there are paradoxes in this regard in the literature. This study aimed at evaluating the correlation between thyroid hormone levels and severity of liver disease.

MATERIALS AND METHODS

We measured thyroid hormone levels in 83 children with liver cirrhosis using radioimmunoassay techniques.

RESULTS

Four patients (4.8%) showed a decrease in the amount of T3 and 9 patients (10.8%) revealed increased levels of T3. Also, decreases were seen in the T4 levels of 7 patients (8.4%), and 4 patients (4.8%) showed increases in levels of T4. The serum albumin levels were lower and international normalized ratio was higher in patients with low T3 and low T4. This study reveals that the Model for End-Stage Liver Disease and Pediatric End-Stage Liver Disease scores are statistically related to the decreased amounts of T4 (P = .036). The Model for End-Stage Liver Disease and Pediatric End-Stage Liver Disease scores and the Child scores were higher in low T3 patients, but this was not significant (P > .05).

CONCLUSIONS

Decreased levels of thyroid hormones are correlated with the severity of disease and can be seen in more advanced cirrhosis. Patients with decreased T4 levels need a liver transplant more immediately than those patients that do not have decreased T4 levels.

Thyroid hormones and growth in health and disease

Thyroid hormones regulate growth by several mechanisms. In addition to their negative feedback effect on the stimulatory hormones thyrotropin-releasing hormone (TRH) and thyrotropin (TSH), thyroid hormones also regulate their receptors in various physiological and pathological conditions. Up-regulation and down-regulation of the thyroid receptors fine-tune the biological effects exerted by the thyroid hormones. Interestingly, the deiodinase enzyme system is another intrinsic regulator of thyroid physiology that adjusts the availability of thyroid hormones to the tissues, which is essential for normal growth and development. Almost all chronic diseases of childhood impair growth and development. Every disease may have a unique mechanism to halt linear growth, but reduced serum concentration or diminished local availability of thyroid hormones seems to be a common pathway. Therefore, the effects of systemic diseases on thyroid physiology must be taken into consideration in the evaluation of growth retardation in affected children.

Hyperthyroidism and jaundice

Development of hyperbilirubinemia, concurrent or subsequent to hyperthyroidism, can be due to thyrotoxicosis per se, or due to drug treatment of hyperthyroidism. Other rare conditions: autoimmune thyroid disease, or causes unrelated to hyperthyroidism like viral hepatitis, alcohol abuse, sepsis, cholangitis, or as a side effect of certain medications. In this article, we review these causes of co-existent hyperthyroidism and jaundice. We also highlight the changes to be expected while interpreting thyroid function tests vis-a-vis liver function tests in this subgroup of patients.

Thyroid hormones and thyroxine-binding globulin in relation to liver function and serum testosterone in men with alcoholic cirrhosis

In 73 euthyroid male patients with histologically verified alcoholic cirrhosis, thyroid hormones, thyroxine-binding globulin (TBG) and testosterone concentrations (total, non-protein- and non-SHBG-bound) were studied in relation to each other and to the degree of liver dysfunction. Serum concentrations of triiodothyronine (T3) decreased significantly (p less than 0.05) and thyroid-stimulating hormone (TSH) increased with progressing liver dysfunction. Serum concentrations of tetraiodothyronine (T4), TBG and T4/TBG ratio did not correlate significantly with liver function. Serum T3 concentrations correlated significantly (Kendall Tau-beta = -0.33, p = 0.001) with total serum testosterone concentrations, while there was a negative correlation (Kendall Tau-beta = -0.20, p = 0.025) between testosterone and TSH values. No correlation was found between testosterone concentrations and serum levels of TBG. It is proposed that the association between T3 and TSH on one hand and testosterone concentrations on the other reflects a covariation of these variables with liver function. The TBG level was normal in most patients and was not correlated to testosterone concentrations.

Increased serum reverse triiodothyronine levels at diagnosis of hepatocellular carcinoma in patients with compensated HCV-related liver cirrhosis

OBJECTIVE

The aim of this study was to investigate changes in thyroid hormone metabolism in relation to the development of hepatocellular carcinoma (HCC) in patients with HCV-related liver cirrhosis.

MATERIALS AND METHODS

The study group (Group A) comprised 31 patients (25 M, 6 F; median age 62.1 years, range 54.0-81.5 years) affected by HCV-related liver cirrhosis with superimposed HCC. Acute and chronic systemic disease, other than cirrhosis, inducing 'euthyroid sick syndrome' was excluded in all patients. Serum TSH, FT4, FT3, rT3, and thyroxine-binding globulin (TBG) levels were retrospectively evaluated in frozen aliquots drawn at the time of tumour diagnosis and every 6 months for 3-7 years before HCC diagnosis. The control group (Group B) comprised 29 patients affected by HCV-related liver cirrhosis without HCC, matched for sex, age and grade of liver dysfunction.

RESULTS

At the time of HCC diagnosis, all patients in Group A were euthyroid with serum TSH, FT4, FT3 and TBG values not significantly different from those of cirrhotic patients of Group B. However, at diagnosis Group A patients had serum rT3 values that were significantly higher than those in Group B (35.0 ng/dl, range 12.0-162.0 vs. 19.0 ng/dl, range 10.0-51.0; Group A vs. Group B; P < 0.001). Serum rT3 values above the normal range were found in 12 patients in Group A (38.7%) but in only one of the patients from Group B (3.4%) (chi2 10.2; P = 0.001). The serum rT3 levels were not significantly correlated to the Child grade of liver cirrhosis (rho 0.1; P = 0.5). The intrasubject analysis demonstrated that a significant increase in serum rT3 levels occurred at the time of HCC diagnosis but serum FT4, FT3 and TSH values did not change significantly. A receiver operating curve (ROC) demonstrated that a 6-monthly increase in serum rT3 levels of at least +22.5% identified patients with HCC with a diagnostic accuracy of 81.7%.

CONCLUSIONS

Our study has demonstrated that development of hepatocellular carcinoma is accompanied by a significant increase in serum rT3 levels in patients with low-grade HCV-related liver cirrhosis who had no other illness causing the 'euthyroid sick syndrome'.

The liver in other (nondiabetic) endocrine disorders

The liver has a major role in the proper maintenance of intermediate metabolism and endocrine homeostasis. It contains enzymes that are essential for hormonal biotransformation and the regulation of numerous metabolic reactions, which control hormone metabolism. The liver also manufactures several proteins, which carry circulating hormones to their effector sites. The endocrine system exerts tight control of the metabolic reactions within the liver, which also can be disturbed by endocrine disorders. These types of interactions and the effects of the exogenous hormones and the drugs that are used as treatment for hormonal disorders are discussed.

Fifty years of experience with propylthiouracil-associated hepatotoxicity: what have we learned?

The aim of this study was to determine the optimal management of patients with propylthiouracil (PTU) hepatotoxicity. 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 Fisher's 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.

Clinical associations between thyroid and liver diseases

The liver has an important role in thyroid hormone metabolism and the level of thyroid hormones is also important to normal hepatic function and bilirubin metabolism. Besides the associations between thyroid and liver diseases of an autoimmune nature, such as that between primary biliary cirrhosis and hypothyroidism, thyroid diseases are frequently associated with liver injuries or biochemical test abnormalities. For example, thyroid diseases may be associated with elevation of alanine aminotransferase and alkaline phosphatase, which is mainly of bone origin, in hyperthyroidism and aspartate aminotransferase in hypothyroidism. Liver diseases are also frequently associated with thyroid test abnormalities or dysfunctions, particularly elevation of thyroxine-binding globulin and thyroxine. Hepatitis C virus infection has been connected with thyroid abnormalities. In addition, antithyroid drug therapy may result in hepatitis, cholestasis or transient subclinical hepatotoxicity, whereas interferon (IFN) therapy in liver diseases may also induce thyroid dysfunctions. These thyroid-liver associations may cause diagnostic confusions. Neglect of these facts may result in over of under diagnosis of associated liver or thyroid diseases and thereby cause errors in patient care. It is suggested to measure free thyroxine (FT4) and thyroid-stimulating hormone (TSH) which are usually normal in euthyroid patients with liver disease, to rule out or rule in coexistent thyroid dysfunctions, and consider the possibility of thyroid dysfunctions in any patients with unexplained liver biochemical test abnormalities. It is also advisable to monitor patients with autoimmune liver disease or those receiving IFN therapy for the development of thyroid dysfunctions, and patients receiving antithyroid therapy for the development of hepatic injuries.

Nicotinic acid-induced toxicity associated with cytopenia and decreased levels of thyroxine-binding globulin

We report the occurrence of cytopenia and hypothyroxinemia attributed to decreased levels of thyroxine-binding globulin in patients receiving nicotinic acid. We describe two patients in whom hypothyroxinemia developed while they were taking nicotinic acid; these patients also had decreased levels of thyroxine-binding globulin. Results of all thyroid function tests returned to normal when use of the nicotinic acid was discontinued. In one patient, leukopenia and thrombocytopenia developed during nicotinic acid therapy alone. These conditions were reversed after the drug regimen was discontinued. In another patient, leukopenia and thrombocytopenia developed during combination nicotinic acid and lovastatin therapy. When administration of both drugs was discontinued, the hematologic abnormalities, which could have been due to either nicotinic acid or lovastatin, diminished. We suggest that cytopenia may develop in patients receiving nicotinic acid; thus, thyroid function tests should be interpreted in light of a possible decreased level of thyroxine-binding globulin.

Thyroid function tests in acute viral hepatitis: relative reduction in serum thyroxine levels due to T4-TBG binding inhibitors in patients with severe liver cell necrosis

Thyroid function tests were evaluated in 34 patients with acute viral hepatitis (AVH) and in 38 healthy controls (C). As expected, AVH patients displayed a significant increase in T4, rT3 and TBG serum levels with respect to C, while FT4 and TSH concentrations were similar. A positive correlation between TBG and T4 was evident in C, but not in AVH. In this group there was, instead, an inverse correlation between the sum of serum levels of GOT + GPT and T4 concentrations. When AVH patients were divided in "high necrosis" (HN, serum GOT + GPT greater than 2000 UI/l) and "low necrosis" (LN, serum GOT + GPT less than 2000 UI/ml) groups, we found a significant reduction in both T4 and T3 serum concentrations in HN with respect to LN, despite similar levels of TBG, albumin, FT4 and TSH. The hypothesis that thyroid-hormone binding inhibitors (THBI), released during severe liver cell injury, accounted for an impaired serum binding capacity in HN-AVH, was confirmed by the significant increase in FT4/T4 ratio and by the demonstration of THBI activity in pooled sera of these patients, with respect to LN subgroup. Our present finding may clarify the unexplained observation of reduced T4 levels in patients with fulminant hepatitis and the ominous prognostic significance of a "low T4 syndrome" in subjects with severe liver disease and/or other systemic illnesses.

Thyroid gland volume and thyroid function during and after acute hepatitis infection

Thyroid function, the occurrence of goiter, and ultrasonically determined thyroid gland volume were investigated in 23 consecutive nonalcoholic patients with acute viral hepatitis during and six months after recovery, and compared with data obtained from 23 matched controls. Seven patients had clinically detectable goiter during disease, but only one after recovery (P less than 0.05). Median thyroid volume was 28 mL (range 15 to 42 mL) compared with 18 mL (range 12 to 27 mL) after recovery (P less than 0.001), and 17 mL (range 11 to 24 mL) in the controls (P less than 0.001). During acute hepatitis, serum levels of thyroxine, thyroxine binding globulin, and free thyroxine index were significantly increased while triiodothyronine and thyrotropin levels were unaltered and triiodothyronine resin uptake and free triiodothyronine index levels were decreased. After recovery all thyroid variables were normalized. In conclusion, acute liver disease was associated with a marked increase in thyroid volume, but the study did not clarify the mechanism underlying thyroid enlargement.

Recent advances in routine thyroid function testing

Thyroid function tests are one of the most common of endocrine laboratory investigations requested by general clinicians. The tests used therefore have to be efficient at identifying thyroid disease, monitoring treatment, and handling large numbers of tests. Recent advances in methodology have expanded both the range of in vitro thyroid function tests available and the techniques by which the well-established tests may be performed. This article reviews the methods and analytical and clinical performance of the routine tests currently available, concentrating particularly on the relatively new ones, and speculating on their role in strategies for the laboratory investigation of thyroid function.