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PubMed1981

Plasma levels of thyroxine and triiodothyronine in women with breast cancer.

24-hour mean plasma levels of T3 and T4 were compared in 29 rigorously selected breast cancer patients (all stages) and 27 healthy women, and 8 A.M. "spot" plasma T4 levels were compared in 43 consecutive unselected breast cancer patients (all stages), 22 women with other-than-breast cancer, 21 women with miscellaneous non-cancerous illnesses, and the same 27 healthy women. The 24-hour T3 levels were the same in the breast cancer patients and healthy controls, but the 24-hour T4 levels were significantly higher in the cancer patients (7.7 vs 5.8 micrograms/dl, p less than 0.001); equal elevations were present in all stages of cancer. Spot T4 levels were likewise significantly higher in the breast cancer patients than in the healthy controls (8.8 vs 7.3 micrograms/dl, p less than 0.005). The women with other-than-breast cancer and the women with miscellaneous non-cancerous illnesses also showed significant elevations of spot T4 levels, indistinguishable from those of the breast cancer patients. It is concluded that breast cancer patients as a group show significant hyperthyroxinemia and that this finding may represent a second nonspecific abnormality of thyroid hormones in disease, hypotriiodothyroninemia (low-T3 syndrome) being the first.

Adult↗
PubMed1994

Systematic differences between commercial immunoassays for free thyroxine and free triiodothyronine in an external quality assessment program.

Data collected in a national external quality assessment program for free thyroxine (fT4) and free triiodothyronine (fT3) were analyzed to evaluate the performance of 10 method/kits with 26 control samples distributed to approximately 170 laboratories. The control materials were normal serum pools, pooled sera supplemented with thyroid hormones, a pregnancy serum pool, serum pooled from patients with familial dysalbuminemic hyperthyroxinemia (FDH), and a normal serum pool progressively diluted. The between-laboratory variability (CV) was approximately constant in normal and supplemented pools for fT4 (15.3%) and fT3 (24.0%) but markedly increased in diluted, pregnancy, and FDH pools (21.9-35.2% for fT4 and 28.6-66.5% for fT3) because of increases in systematic between-kit differences in control samples with altered binding-protein capacity. Moreover, free hormone concentrations measured in progressively diluted sera averaged lower than in undiluted samples. This decrease of concentration was less for back-titration or labeled-antibody techniques and greater for labeled-analog methods; only the method involving adsorption to cross-linked dextran (Sephadex) was unaffected by dilution. Evaluation of the reproducibility of the method/kits showed between-assay, between-laboratory precision ranging from 7.8% to 17.0% for fT4 and from 9.8% to 20.3% for fT3.

Female↗
PubMed1993

Free thyroxine assessed with three assays in sera of patients with nonthyroidal illness and of subjects with abnormal concentrations of thyroxine-binding proteins.

Three methods for estimating free thyroxine (FT4) in serum were studied: equilibrium dialysis, the SPAC-ET FT4 radioimmunoassay kit, and the Amerlite MAB FT4 luminometric assay. Serum samples from 10 subjects with above-normal thyroxine-binding globulin (TBG), 6 with low TBG, 30 with familial dysalbuminemic hyperthyroxinemia (FDH), 13 with nonesterified fatty acids (NEFA) concentrations in serum > 1.0 mmol/L, and 178 patients with various degrees of nonthyroidal illness (NTI) were measured and compared with samples from 42 euthyroid blood donors. The Amerlite MAB FT4 assay compared well with equilibrium dialysis, whereas the SPAC-ET assay averaged 40% lower. All three assays were not influenced by changes in TBG and showed no or only little changes in the presence of NEFA. Mean FT4 values in the FDH samples were somewhat higher than in controls when measured with the SPAC-ET assay, about equal with equilibrium dialysis, and somewhat below the mean control value with the Amerlite MAB FT4 assay, although individual results were within the control reference range. In NTI patients, no FT4 values were below the control reference range by the Amerlite MAB FT4 assay, 4 of 178 were below this range by equilibrium dialysis, and 1 of 178 was below this range by the SPAC-ET assay. In all assays a large proportion of the NTI samples showed FT4 values above the control reference range, a result that will interfere with the efficacy of these assays for assessing thyroid function in NTI patients.

Dialysis↗
PubMed1997

Screening and biochemical characterization of transthyretin variants in the Portuguese population.

The study of pathogenic and nonpathogenic transthyretin (TTR) variants is very important for the understanding of such TTR-related diseases as hereditary amyloidosis and also to establish a relationship between the structure and function of the molecule. Variants with clinical manifestations can be easily detected, but clinically silent variants can be detected only by population screening programs using specialized techniques. Hybrid isoelectric focusing (HIEF) in extremely flattened immobilized pH gradients (IPG) allows the detection of even neutral amino acid substitutions and has been used to analyze approximately 5,000 samples from the Portuguese population. Comparison with samples from carriers of three known TTR mutations (Met 30 associated with hereditary amyloidosis, Met 119, and Asn 90) was also made. In this study we detected: (1) 8 individuals carriers of TTR Met 30, (2) 35 carriers of TTR Met 119, (3) 12 carriers of TTR Asn 90, (4) 1 compound heterozygote for TTR Met 30/Met 119, and (5) 5 variants that presented a different pattern from the controls used. We also performed DNA sequencing analyses of two of the variants with the different band pattern in HIEF. The individuals were found to be carriers of TTR Ile 122 and TTR Thr 190, respectively. All the mutations detected, except for Asn 90, result from substitutions in CpG hot spots and thus can be rather frequent in the populations. Studies on the clinical evolution of the compound heterozygotes and on the physical-chemical properties of these hybrid TTRs will help to understand the pathogenicity associated with TTR.

Amyloidosis↗
PubMed2005

Effects of experimental increases and decreases in thyroxine levels on the extent of cataleptic freezing reactions in rats.

Numerous clinical observations have provided evidence for a tight connection between impairments in the functions of the hypothalamo-hypophyseal-thyroid system and nervous and mental disorders. The aim of the present work was to compare the effects of experimental decreases and increases in blood thyroxine levels on the extents of two types of pathological freezing reaction in male Wistar rats--spontaneous catalepsy and catalepsy evoked by pinches at the nape of the neck (pinch-induced catalepsy). Chronic administration of the thyroxine synthesis inhibitor propylthiouracil (5 mg/kg/day for 28 days) significantly decreased the blood hormone level and sharply increased the proportion of animals showing spontaneous catalepsy and the immobility time, but had no effect on the extent of pinch-induced catalepsy. At the same time, chronic administration of thyroxine (0.1 mg/kg/day for 28 days), which produced significant increases in blood hormone levels, had no effect on the extent of spontaneous catalepsy but significantly increased the proportion of animals showing pinch-induced catalepsy and the duration of this type of catalepsy. It is concluded that both insufficiency and excess of thyroid hormones have cataleptogenic actions, but enhance different types of catalepsy.

Animals↗
PubMed1991

The prognostic significance of thyroid function in mania.

Free thyroxine index (FT4I) and thyroxine (T4) levels were measured in 31 manic patients shortly after admission to a psychiatric hospital. Over one-third had elevated thyroid hormone levels, and this was largely due to increases in FT4I. Increased FT4I levels were associated with greater sleep disturbance and with being male, and were negatively associated with having had hospital admissions in the past six months. More interestingly, however, low FT4I levels prospectively predicted more hospital admissions in the 12 months from index admission, and this was not due to past admissions predicting future admissions. This adds to the growing literature on important relationships between thyroid hormones and treatment outcome in patients with affective disorders.

Adolescent↗
PubMed1988

Hyperthyroxinaemia in hepatocellular carcinoma: relation to thyroid binding globulin in the clinical and preclinical stages of the disease.

Serum thyroxine was significantly higher in 59 patients with hepatocellular carcinoma than in normal subjects, patients with uncomplicated cirrhosis (48), or other primary tumours with or without hepatic metastases (50). Elevated thyroxine levels appeared attributable to high levels of thyroxine binding globulin which showed a positive linear correlation with serum thyroxine in all groups studied. Despite this hyperthyroxinaemia all patients appeared clinically euthyroid and, consistent with this, T3 was elevated in only one patient and the free thyroxine index was normal in all. Amongst a group of 25 cirrhotic patients who were followed-up for between 12 and 72 months, there was a striking dissociation between the TBG values of those destined to develop HCC and those who did not. In the former group TBG rose steadily with time whereas in the latter group levels remained stable, or, more often, fell. The rises in TBG occurred prior to any clinical signs of tumour development and may be one of the earliest serological changes to occur during carcinogenesis in the cirrhotic liver.

Adolescent↗
PubMed1998

Gestational transient hyperthyroxinaemia (GTH): screening for thyroid function in 23,163 pregnant women using dried blood spots.

OBJECTIVE: Transient elevation of serum free T4 (gestational transient hyperthyroxinaemia; GTH) occurs occasionally during normal pregnancy, especially in early gestation. However, the frequency of GTH and its clinical features remain unclear to date. The aim of this study was to determine the occurrence rate of GTH and the relation between serum levels of hCG, free T4 (fT4), and TSH in a large number of pregnant women. DESIGN: The four criteria of GTH were as follows: (1) no past history of thyroid disease, (2) negative tests for MCHA and TGHA, (3) no multiple pregnancies or trophoblastic disease and (4) transient hyperthyroxinaemia at less than 16 weeks of gestation. Thyroid function and hCG levels in 23,163 pregnant women were evaluated by mass sreening. If individual fT4 levels were more than the upper limit, blood re-sampling and the clinical and laboratory analysis of thyroid function were performed to exclude women with thyroid disease. The concentrations of hCG, fT4, and TSH in women with GTH and normal pregnant controls (n = 218) were compared. Regression analysis was performed for the comparison between hCG, fT4, and TSH levels in women with GTH. MEASUREMENTS: Blood samples were obtained using dried blood spots. Blood levels of fT4 was measured by radioimmunoassay, TSH and hCG were measured by fluoroimmunoassay. Anti-microsome antibody (MCHA) and anti-thyroglobulin antibody (TGHA) were measured by indirect agglutination reaction. RESULTS: GTH was observed in 66 of 23,163 women. The overall occurrence rate of GTH was 0.285%. In 22 of the 66 GTH women, serum TSH was undetectable. Using regression analyses, the concentration of fT4 was correlated with hCG levels in women with GTH (P < 0.05, r = 0.269), whereas the concentration of TSH was not correlated with hCG or fT4 level. The concentrations (M +/- SD) of fT4, TSH, and hCG in women with GTH were 42.5 +/- 12.3 pmol/l, 0.20 +/- 0.31 mU/l and 190.2 +/- 98.8 x 10(3) IU/l, whereas those of controls were 14.6 +/- 3.8 pmol/l, 1.43 +/- 1.25 mU/l and 60.1 +/- 45.1 x 10(3) IU/l. The concentrations of fT4 and hCG were significantly (P < 0.0001) higher than those of normal controls, and TSH was significantly (P < 0.0001) lower than those of normal controls. CONCLUSION: The occurrence rate of gestational transient hyperthyroxinaemia was 0.285%, and could possibly be attributed to increased levels of circulating hCG. Based on the data obtained from a large number of pregnant women, we propose gestational transient hyperthyroxinaemia as a definite clinical entity.

Blood Specimen Collection↗
PubMed1998

[Pseudohyperthyroxinemia in endemic sprue--reversibility with a gluten-free diet].

HISTORY: An increased concentration of free T3 (fT3) with normal TSH was repeatedly measured in a 58-year-old man with diarrhoea. Hyperthyroidism was diagnosed and he was treated with thyrostatic drugs. INVESTIGATIONS: Referred to our clinic, fT4 concentration, determined by routine ELISA, was found to be raised to 33.9 pmol/l, while fT3 and TSH levels were within normal limits. But the equilibrium-dialysis method gave a normal serum level also for fT4. Gastroscopy suggested coeliac disease, confirmed histologically. TREATMENT AND COURSE: The symptoms quickly improved on a gluten-free diet and the fT4 level returned to normal values even on routine measurement. CONCLUSION: The raised fT4 level with non-suppressed TSH was only revealed as a false finding by special non-routine laboratory methods. The reversibility and the close time relationship of the reported laboratory data with the clinical manifestations of the concomitant coeliac disease strongly suggested that changes in serum in the course of the latter disease played a role in these misleading laboratory results. An interference of coeliac disease with some laboratory tests has been previously described.

Celiac Disease↗
PubMed1992

Detection of albumin binding abnormalities in sera of patients with familial dysalbuminaemic hyperthyroxinaemia using isoelectric focusing.

Definitive diagnosis of familial dysalbuminaemic hyperthyroxinaemia (FDH) requires finding a high concentration of [125I]T4 bound to albumin. We used isoelectric focusing (IEF) in agarose gels to study the sera of three members of a family with FDH and compared the distribution of [125I]T4 obtained by IEF with that obtained by conventional agarose gel electrophoresis (AGE). Both IEF and AGE confirmed the diagnoses of FDH. In case #1, the % [125I]T4 bound to albumin was 15.2 and 20.0, with IEF and AGE, respectively, in case #2 23.6 and 26.5, and in case #3, 22.1 and 23.0, compared to normal controls of 5.9 and 7.4, respectively. IEF has not previously been used to diagnose FDH, to our knowledge. IEF has the advantage of eliminating TBG interference with albumin migration, which can potentially complicate the diagnosis of FDH when the AGE method is used. To date, reverse flow electrophoresis, a more cumbersome method with poorer resolution than IEF, has been utilized to eliminate TBG interference. IEF, in agarose gels, is a relatively simple and accurate method to diagnose FDH, and avoids artifacts which may be encountered with AGE.

Adult↗
PubMed2001

Thyroid dysfunction in children with Down's syndrome.

UNLABELLED: Thyroid function tests were carried out on 320 children with Down's syndrome aged between 5 d and 10 y. Thyroid function was normal in 230 patients (71.9%) and abnormal in 90 (28.1%). Six patients (1.8%) had primary congenital hypothyroidism, one patient had acquired hypothyroidism and two had transient hyperthyrotropinaemia of the newborn. Sixteen of the remaining 81 patients (25.3%) had compensated hypothyroidism with increased thyroid-stimulating hormone (TSH) levels (11-20 mU l(-1)). Their T4 levels were found to be either normal or close to the lower limit of normal. These cases were started on thyroxine therapy. Sixty-five of the 81 patients had a mild compensated hypothyroidism with mild TSH elevation (6-10 mU l(-1)). None of the patients had hyperthyroidism. The antithyroid antibodies were positive in the acquired hypothyroidism case. CONCLUSION: The prevalence of congenital hypothyroidism was 1.8% in children with Down's syndrome while 25.3% of them had compensated hypothyroidism. It is suggested that Down's syndrome patients with normal thyroid functions and those with compensated hypothyroidism should be followed annually and every 3 mo, respectively. Besides congenital hypothyroidism cases, those with TSH levels between 11 and 20 mU l(-1) may benefit from treatment with low-dose thyroxine.

Child↗
PubMed2001

Abnormal serum free thyroid hormone levels due to heparin administration.

Fractionated or unfractionated heparin may produce artefactual elevation in measured concentrations of free thyroid hormones. Although the specific cause is unknown, it may be a consequence of displacement of thyroid hormones from their binding sites by free fatty acids liberated in vitro. We describe four cases of heparin-induced abnormalities in free thyroid hormone measurements where some diagnostic confusion was generated. Increasing physician awareness of this poorly appreciated entity may avert diagnostic confusion and unnecessary investigation.

Adult↗
PubMed1990

Thyroxine-binding prealbumin gene polymorphism: a population study.

The human thyroxine-binding prealbumin (TBPA) gene was examined for restriction fragment length polymorphism (RFLP) in normal subjects and a subject with euthyroid hyperthyroxinaemia, due to increased thyroxine binding by TBPA, using 16 restriction enzymes. Only Taq I and Msp I were shown to detect RFLPs. In a male of the normal population and one of his daughters, an additional Taq I site was found in the 3'-flanking region of the TBPA gene. The RFLP in a subject with euthyroid hyperthyroxinaemia was due to the deletion of a MspI site. All three subjects with RFLPs were heterozygous.

Adult↗
PubMed1994

Familial dysalbuminaemic hyperthyroxinaemia and inherited partial TBG deficiency: first report.

BACKGROUND: Abnormalities of the serum thyroid hormone binding proteins are not uncommon but, when properly assessed, they do not present diagnostic difficulties. In contrast, the presence of two inherited defects of thyroid hormone transport, of the type presented in the family described here, may cause a major problem in diagnosis and has not been described previously. METHODS: All conventional thyroid function tests were carried out. In addition, thyroid hormone binding to serum proteins was assessed by agarose gel electrophoresis, and thyroxine binding globulin by immunoassays and by immunodiffusion. The affinity of TBG for thyroxine and its maximal binding capacity were assessed by Scatchard analysis. RESULTS: Tests carried out on 22 members of the family revealed familial dysalbuminaemic hyperthyroxinaemia in 10 family subjects. All five living siblings of the propositus had familial dysalbuminaemic hyperthyroxinaemia and two tested transmitted this trait to their children and grandchildren. This was not the case with the propositus. Partial thyroxine binding globulin deficiency only, inherited presumably from the propositus' mother, was found in two family members. Both thyroxine binding globulin deficiency and familial dysalbuminaemic hyperthyroxinaemia were detected in the propositus and in his male nephew, masking the typical laboratory abnormalities associated with each of these defects. CONCLUSIONS: Coexistence of two inherited defects of thyroid hormone transport proteins produce atypical thyroid function test abnormalities, which can be misinterpreted as thyroid hormone dysfunction.

Adult↗