The spectrum of thyroid dysfunction in an Australian hepatitis C population treated with combination Interferon-α2β and Ribavirin

BACKGROUND: The study aims to assess the pattern of thyroid response to combination Interferon-α2β (IFN-α) and Ribavirin (RBV) anti-viral therapy in an Australian hepatitis C cohort. These include the prevalence of thyroid dysfunction (TD) including hyperthyroidism and hypothyroidism and their possible predictors, the common overall pattern of thyroid function tests whilst receiving therapy and TD outcomes, and the correlation with HCV status outcome. METHODS: A retrospective analysis of all medical records was performed to assess thyroid function in Hepatitis C Virus (HCV) patients who were treated at the Hunter Area hepatitis C treatment center between 1995 and March 2004. The centre is part of the John Hunter hospital, a major tertiary referral centre in New South Wales, Australia. RESULTS: There were 272 cases available for review. The prevalence of TD is 6.7 percent and is made up predominantly of females (80 percent). There were 3 (1.1 percent) cases of hyperthyroidism with 2 (67 percent) females. Thirteen out of fifteen (80 percent) cases of hypothyroidism were females with the overall prevalence of 5.5 percent. The majority of hypothyroid patients still required Thyroxine supplement at the end of follow up. CONCLUSION: Ninety three percent of HCV treated patients have intact thyroid function at the end of treatment. The predominant TD is hypothyroidism. The predominant pattern of thyrotoxicosis (TTX) is that of thyroiditis although the number is small. Graves' like disease was not observed. People with pre-existing thyroid auto-antibodies should be closely monitored for thyroid dysfunction, particularly hypothyroidism

Serum levels of carboxyterminal cross-linked telopeptide of type I collagen (ICTP) in the differential diagnosis of the syndromes of inappropriate secretion of TSH

BACKGROUND AND OBJECTIVE Serum TSH assay is a very sensitive and specific index of thyroid hormone (TH) action. Nevertheless, in particular clinical situations, such as those of inappropriate TSH secretion, the measurement of additional parameters evaluating peripheral TH action may be required in order to achieve a correct diagnosis and to assess the impact that thyroid hormone have on a given tissue. The availability of a specific RIA for serum carboxyterminal cross-linked telopeptide of type I collagen (ICTP) prompted us to study the usefulness of this specific marker of bone resorption in the differential diagnosis of thyroid disorders.DESIGN Serum ICTP levels were measured in: (a) 10 patients with TSH-secreting pituitary adenoma (TSH-oma), (b) 40 with thyroid hormone resistance (RTH), as well as in (c) 28 patients with Graves' disease or toxic nodular goitre, (d) 31 with autoimmune primary hypothyroidism (PH) and in 8 of them during L-T4 replacement therapy, (e) 23 with central hypothyroidsim (CH) during L-T4 therapy and 2 months after its withdrawal, and (f) 26 during TSH-suppressive treatment for goitre or non-metastatic differentiated thyroid cancer. Results were compared with those obtained in 2 groups of normal controls (Group A, n=61, age range: 23-68 years; Group B, n=32, age range: 6-15 years).METHODS Serum TSH, free T4 (FT4) and free T3 (FT3) were measured by immunofluorometric assays. Serum ICTP was measured by a specific RIA with a sensitivity of 0.5 +/- 0.1 mu g/l, and intra-and interassay coefficients of variation lower than 6%.RESULTS Mean values of serum ICTP levels in adult controls were 3.8 +/- 1.6 (+/- SD) mu g/l, while in pre- or peri-pubertal controls it was higher than in adults (14.4 +/- 3.1 mu g/l). Patients with TSH-oma showed significantly increased ICTP levels (8.7 +/- 5.0 mu g/l, P<0.001 vs controls), in contrast to those with RTH (3.0 +/- 1.0 mu g/l, P<0.02 vs controls). In the differential diagnosis of inappropriate secretion of TSH, ICTP values above 5 mu g/l strongly indicated the presence of a TSH-oma. Circulating ICTP concentrations were definitely high in thyrotoxic patients (9.4 +/- 4.7 mu g/l, P<0.001) and values overlapping the normal range were observed in 8 cases, thus giving to this test a sensitivity and specificity of 71% and 93%, respectively. In contrast, serum ICTP levels in both PH and CH untreated patients were in the normal range, although significantly lower than in controls (2.6 +/- 1.0 and 1.8 +/- 0.7 mu g/l, P < 0.001). During replacement therapy, ICTP levers rose significantly in both hypothyroid groups (5.1 +/- 2.5 and 2.7 +/- 1.3 mu g/l). In 2 CH patients, borderline high ICTP levels (7.0 and 7.1 mu g/l), associated with FT3 concentrations in the upper limit of the normal range, suggested the presence of L-T4 overtreatment; L-T4 dose reduction was followed by the decrease of both indices in a more physiological range (ICTP: 4.2 and 4.7 mu g/l; FT3: 6.5 and 6.0 pmol/l). In patients treated with TSH-suppressive therapy at the minimal effective dose, ICTP levels did not significantly differ from those observed in adult controls (4.3 +/- 2.0 mu g/l). The overall correlations between serum ICTP and FT4 or FT3 levels were highly significant (P<0.001).CONCLUSIONS The present data indicate that serum type I collagen (ICTP) concentrations are modulated by circulating thyroid hormone concentrations, ICTP measurement is particularly useful in the differential diagnosis of the syndromes of inappropriate TSH secretion, in estimating thyroid hormone impact on bone in primary hyperthyroid states, and its longitudinal evaluation may reveal L-T4 overtreatment in patients on substitutive or TSH-suppressive therapy

Maturation of pituitary-thyroid function in the anencephalic fetus

The recent availability of both cordocentesis and ultrasensitive/highly specific immunometric assays for TSH and its subunit determination along with direct "two-step" assays for free thyroid hormone measurement, prompted us to study the maturation of hypothalamic-pituitary-thyroid axis in normal and anencephalic human fetuses from 17 to 26 weeks of gestation. In addition, TSH bioactivity was measured as cAMP accumulation in CHO cells transfected with recombinant human TSH receptor and TSH carbohydrate structure was studied by lectin chromatography. In both normal and anencephalic fetuses, circulating TSH and FT4 levels significantly increased from 17 to 26 weeks of gestation. Circulating FT3 concentrations were very low (0.5-3.1 pmol/l), while alpha-SU levels were very high (20-417 mg/l). Both FT3 and alpha-SU levels did not change from 17 to 26 weeks of gestation and, again, no differences between normal and anencephalic fetuses were recorded. Circulating TSH from both normal and anencephalic fetuses showed an enhanced bioactivity and was more retained on the lectin column than adult TSH, thus indicating that molecules with different carbohydrate structure are circulating during fetal development. In conclusion, the present data demonstrate that the absence of the hypothalamus does not compromise the maturation of pituitary-thyroid function and that the mechanisms underlying the secretion of TSH molecules with elevated bioactivity and different structure of glycosylated chains are not dependent on hypothalamic neuroendocrine control

Autoimmunity and thyroid function in patients with chronic active hepatitis treated with recombinant interferon alpha-2a

The occurrence of thyroid abnormalities and the appearance of organ- and non-organ-specific autoantibodies during long-term recombinant interferon alpha-2a (IFN-alpha) therapy were studies in 86 and 51 consecutive outpatients with hepatitis C and B virus-related chronic active hepatitis (CAH-HCV and CAH-HBV), respectively. Most patients had longstanding community-acquired hepatitis. At baseline, 9.3% of CAH-HCV and 3.9% of CAH-HBV patients showed clinical and/or biochemical signs of thyroid dysfunction. The remaining patients were euthyroid, although anti-thyroid autoantibodies were found in 33/78 (42.3%) of CAH-HCV and in 5/49 (10.2%) of CAH-HBV patients. During IFN-alpha treatment, increased anti-thyroid autoantibody levels were seen in 40% of CAH-HCV initially negative patients, while they became detectable in no more than 10% of CAH-HBV patients. Interferon-alpha-induced hypo- or hyperthyroidism was recorded in 12 of 35 CAH-HCV patients treated for 12 months (34.3%). Only one CAH-HBV patient developed hyperthyroidism. High titers of anti-nuclear autoantibodies (ANA) were recorded at enrolment in 5/36 (13.8%) of CAH-HCV and in 3/16 (18.7%) of CAH-HBV patients. Only one CAH-HCV patient displayed anti-parietal cell antibodies (PCA). After IFN-alpha treatment, ANA were found in 10/28 (35.7%) and PCA in 2/28 (7.1%) of CAH-HCV patients, while an additional CAH-HBV patient developed PCA. but not ANA. However, no signs of systemic autoimmune disease were recorded. In conclusion. more than half of the patients with chronic active hepatitis C, but only one-tenth of those with hepatitis B, displayed thyroid- and/or non-organ-specific autoantibodies prior to or during treatment with IFN-alpha. As most of the antibody-positive patients developed permanent thyroid disorders during IFN-alpha therapy, the risk of development of organ-specific autoimmunity should be assessed carefully and incorporated in the cost/effectiveness analysis in patients with longstanding hepatitis who are candidates for IFN-alpha treatment