Maternal autoimmune thyroid disease and the fetal immune system

OBJECTIVE

Several studies indicate that in utero exposure to maternal autoimmune diseases and transplacental passage of autoantibodies affect the risk of autoimmunity in the offspring, e. g., maternally derived GAD65 autoantibody correlates with decreased risk of type 1 diabetes, whereas thyroid peroxidase autoantibody (TPOAb) positivity at birth is associated with increased incidence of autoimmune thyroid disease later in life. The aim of this study was to identify immunological changes in children born to mothers with thyroid autoimmunity that may be related to in utero exposure to autoantibodies.

DESIGN AND METHOD

Open label prospective analysis of cord blood lymphocytes and serum cytokines by Flow Cytometry in children born to mothers with autoimmune thyroiditis (AIT) (n=31) and to healthy mothers (n=76) and titers of thyroid autoantibodies were determined in cord blood and in maternal peripheral blood at delivery.

RESULTS

We found an increase (almost 30%) in the frequency of cord blood natural killer (NK) cells (p=0.0016) and a minor increase in the subset of T cells expressing NK markers (p=0.028), in children born to AIT mothers. There were no detectable differences in the phenotype or frequency of cord blood memory/activated T cells, including CD4 (+)CD25 (+) T cells, between the 2 groups. The levels of pro-inflammatory cytokines TNF-α, IL-10, IL-12p70, IFN-γ and IL-1β were significantly decreased in offspring of AIT mothers as compared to healthy controls.

CONCLUSIONS

Maternal thyroid autoimmunity and transplacental passage of autoantibodies against thyroid antigens may affect the generation or expansion of cells with NK activity and the secretion of inflammatory cytokines.

Decreased radioiodine uptake values without increase in urinary iodine excretion

A total of 12842 radioiodine uptake measurements (RIU), performed for diagnostic purposes at Malmö General Hospital 1955-75, have been reviewed. In agreement with the general trend in Europe and the USA, there was a significant decrease in uptake during this period. The 24-hour RIU (mean +/- S.D.) was 51 +/- 18% in 1955, 41 +/- 17% in 1965 and 37 +/- 18% in 1975. The 3- and 48-hour uptake values, as well as the protein-bound radioiodine, fell in a parallel fashion. The fall can not be explained by an increased dietary supply of iodine, because the mean urinary excretion did not show any consistent change from 1965 to 1975, apart from a falling trend from 1967 to 1971. The cause of the decrease in thyroid iodine uptake is not elucidated by this study.

A prospective critical evaluation of in vitro thyroid function tests

A number of 2 325 serum samples from a population of in- and outpatients were collected during a six-month period in order to evaluate the usefulness of various thyroid function tests in the clinical laboratory routine. The samples were analysed with the following thyroid function tests: total triiodothyronine (T3) (TT3), total thyroxine (T4) (TT4), free T3 index (FT3I), free T4 index (FT4I) and thyrotropin (TSH). One to two years after the primary evaluation, a follow-up was performed and the final diagnoses were checked in the patients' records. The values of these parameters in the diagnosis of hyperthyroidism were: FT3I greater than FT4I greater than TT3 greater than TT4. The corresponding results in the diagnosis of hypothyroidism were: TSH greater than FT4I greater than FT3I = TT3. No single test could detect both hyper- and hypothyroidism effectively. The only one-step strategy for thyroid evaluation in patients without apparent clinical signs of hyper- or hypothyroidism would therefore be the combined determination of T3 and TSH. The study also showed distinct differences between the reference values of the healthy population and patients without thyroid disorders.

Comparison of some different methods for analysis of thyroid autoantibodies: importance of thyroglobulin autoantibodies

Blood samples from 141 children and adolescents were used to evaluate differences between commercial kits and radioimmunoassay (RIA) methods for detecting thyroid autoantibodies. Thyroglobulin autoantibodies (Tg-Ab) were analyzed with a hemagglutination kit and a RIA; thyroid peroxidase autoantibodies (TPO-Ab) were measured with a gelagglutination assay and a RIA. The results of the antibody tests were compared with thyroid function tests (triiodothyronine [T3], thyroxine [T4], thyrotropin [TSH]) and with the results of ultrasound of the thyroid in antibody-positive patients. The correlation of antibody levels between the two methods was higher for TPO-Ab than for Tg-Ab. Moderate to high levels of TPO-Ab correlated to elevated TSH levels. Autoimmune thyroiditis (AIT) was found in 6 of the 141 children. The RIA-based thyroglobulin assay was the only test that identified autoantibodies in all 6 cases. In contrast, the hemagglutination kit thyroglobulin assay failed to identify 4 of the 6 AIT cases.

Gliadin antibodies in adult insulin-dependent diabetes--autoimmune and immunogenetic correlates

Gliadin antibody (GA) tests used in screening for coeliac disease (CD) frequently yield positive GA results without accompanying CD in cases of diabetes mellitus type 1 (DM-1). To enlighten this phenomenon we screened 848 DM-1 patients for IgA- and IgG-GA. Subsequently, 16 out of 19 high titre GA patients (6 with CD) were compared with 37 low titre DM-1 patients matched for sex, age and disease duration, for autoimmune and immunogenetic markers. Chronic thyroiditis and thyroid peroxidase (TPO) antibody positivity were more frequent in the GA-positive than in the GA-negative sub-group (38 vs. 2.7%, p = 0.003, and 69 vs. 27%, p < 0.00, respectively). The tissue transglutaminase (tTg) IgA titres correlated with CD but not with GA. tTg IgG titres were lower in GA-positive individuals (p = 0.0012). GA-positivity correlated with a higher titre of factor XIII IgA antibodies (p < 0.001). GA-positive DM-I patients were characterised by a distinct immunogenetic profile; the risk of HLA DQB1*02 was lower among GA-positive patients than among GA-negatives (OR 0.4, preventive fraction 0.43). All CD patients were HLA DRB1*03-DQB1* 02-positive, but none of the five patients with normal biopsies. GA-positive patients instead had HLA DRB1*13 in 37.5% as compared to 8.6% in GA-negative (OR 6.4, etiologic fraction 0.32). Thus, the occurrence of positive GA in DM-1 is correlated to TPO antibody positivity, thyroiditis and factor XIII IgA antibodies, but inversely correlated to tTg IgG, and seems to be associated with another HLA haplotype than that previously found to be associated with CD.

Persistent high prevalence of thyroid antibodies after immunosuppressive therapy in subjects with glomerulonephritis. A prospective three-year follow-up study

The prevalence of thyroid antibodies, indicating an autoimmune thyroiditis, has been shown to be significantly increased in patients with autoimmune diseases. A 3-year prospective follow-up study of 42 patients with biopsy-confirmed glomerulonephritis is presented. Although the majority of patients had been treated with immunosuppressants, the prevalence of thyroid peroxidase antibodies was unchanged in both females and males, 47 and 15% respectively, at follow-up. Likewise, the prevalence of thyroglobulin antibodies was unaffected as was that of antinuclear antibodies (ANA) when analysing males and females together. However, for males there was a trend to higher prevalence for ANA at follow-up. On the other hand, the prevalence of antineutrophil cytoplasmic antibodies declined. Furthermore, thyroid antibodies were not restricted to membranous nephropathy, and notably found in 4 out of the 8 patients with vasculitis.

Prevalence of beta-cell and thyroid autoantibody positivity in schoolchildren during three-year follow-up

The prevalence of autoantibodies against the 65 kD isoform of glutamic acid decarboxylase (GAD65Ab), insulin (IAA), islet cells (ICA), thyroid peroxidase (TPOAb) and thyroglobulin (TgAb), in relation to HLA-DR types, was assessed in 310 (HLA in 280) twelve-year-old children during three-year follow-up. Altogether, 26.8% (83/310) of the children were found to carry at least one autoantibody. The HLA-DR3/DR4 genotype was significantly more prevalent in the subgroup of children GAD65Ab-positive on at least one occasion than among GAD65Ab-negative children [33% (2/6) vs. 5% (12/274); p = 0.031, as was the HLA-DR4/x genotype among children seropositive for at least one thyroid autoantibody, compared to the corresponding seronegative subgroup 152% (34/65) vs. 34% (74/215); p=0.01]. The proportion of children seropositive in at least one of the three tests was 1.9% (6/310) for GAD65Ab, 2.6% (8/310) for IAA, 5.2% (16/310) for ICA, 11.3% (35/310) for TPOAb and 19.4% (60/310) for TgAb. All autoantibodies except GAD65Ab tended to disappear during follow-up, and at the three-year follow-up IAA had disappeared in 50% (2/4) of cases, ICA in 67% (6/9), TPOAb in 30% (6/20) and TgAb in 38% (18/47) of cases. The turnover of seropositive subjects and the large proportion of children seropositive for at least one islet or thyroid autoantibody during a three-year follow-up suggest transient autoantibodies to be more common than is discernible in cross-sectional investigations.

Previous exposure to measles, mumps, and rubella--but not vaccination during adolescence--correlates to the prevalence of pancreatic and thyroid autoantibodies

OBJECTIVE

This study was designed to determine whether a relationship exists between previous exposure to measles, mumps, and rubella (MMR) by natural infection or vaccination or by new immunization with MMR vaccine, and either the presence or levels of autoantibodies against thyroid cell and pancreatic beta-cell antigens.

METHODS

Antibodies against MMR and autoantibodies against thyroglobulin, thyroid peroxidase, pancreas islet cells (ICA), islet cell surface, glutamic acid decarboxylase 65k autoantibodies, and insulin were studied before, and 3 months after, vaccination with combined MMR vaccine in 386 school children between 11 and 13 years of age.

RESULTS

The vaccination changed neither the prevalence nor the level of autoantibodies. Children with rubella antibodies before vaccination had higher levels of ICA than did the rubella seronegative children. In contrast, thyroid autoantibody levels and prevalence were lower in children with antibodies against measles, mumps, or both before vaccination than in children without those antibodies.

CONCLUSIONS

Previous natural infection or vaccination against measles, mumps, or both seemed to have an inhibitory effect on the development of thyroid autoantibodies. In contrast, children with previous exposure to rubella had higher levels of ICA. No evidence was found that MMR vaccination during adolescence may trigger autoimmunity.

The coexistence of thyroid autoimmunity in children and adolescents with various allergic diseases

The aim of our study was to investigate the coexistence of thyroid autoimmunity and allergic diseases. The prevalence of thyroid autoantibodies was studied in sera from 140 children with different kinds of allergic diseases, 370 11-13-y-old schoolchildren without allergic diseases serving as controls. The prevalence of thyroid peroxidase autoantibodies was found to be higher among the patients than in the control group, 11.4% vs 5.4% (p < 0.05). Ultrasound investigation identified autoimmune thyroiditis in 4.3% (6/140) of the series, which was later confirmed with fine needle aspiration in all six cases, four of which were unknown prior to the study. Our findings may be useful to alert clinicians that thyroid diseases may be superimposed on allergic children.

Plasma total homocysteine levels in hyperthyroid and hypothyroid patients

We found a higher plasma concentration of total homocysteine (tHcy), an independent risk factor for cardiovascular disease, in patients with hypothyroidism (mean, 16.3 micromol/L; 95% confidence interval [CI], 14.7 to 17.9 micromol/L) than in healthy controls (mean, 10.5 micromol/L; 95% CI, 10.1 to 10.9 micromol/L). The tHcy level of hyperthyroid patients did not differ significantly from that of the controls. Serum creatinine was higher in hypothyroid patients and lower in hyperthyroid patients than in controls, whereas serum folate was higher in hyperthyroid patients compared with the two other groups. In multivariate analysis, these differences did not explain the higher tHcy concentration in hypothyroidism. We confirmed the observation of elevated serum cholesterol in hypothyroidism, which together with the hyperhomocysteinemia may contribute to an accelerated atherogenesis in these patients.

High prevalence of thyroid autoantibodies at diagnosis of insulin-dependent diabetes mellitus in Swedish children

The prevalence of thyroglobulin autoantibodies and that of thyroid peroxidase autoantibodies were studied in serum samples from 52 children with insulin-dependent diabetes mellitus, sampled at diagnosis and before the start of insulin treatment, with 386 non-diabetic schoolchildren (11 to 13 years of age) serving as control subjects. Using exactly the same sensitive solid-phase immunosorbent radioassay for both thyroid autoantibodies, with comparable sensitivity, we found the prevalences of both autoantibodies to be higher in the insulin-dependent diabetes mellitus group than in the control group, the difference being most pronounced for thyroid peroxidase autoantibodies. Thyroglobulin autoantibodies were positive in 33% of the diabetics versus 14% in the control group (p = 0.002), and thyroid peroxidase autoantibodies were positive in 38% versus 6% (p = 0.0001). The high prevalence of thyroid autoantibodies already at diagnosis stresses the importance of early screening for thyroid disease in patients with insulin-dependent diabetes mellitus.

The impact of thyroid autoimmunity in children and adolescents with Down syndrome

The extent to which autoimmunity contributes to thyroid dysfunction in individuals with Down syndrome (DS) has not been clarified. In this study, we used the same highly sensitive method to detect both thyroid autoantibodies (thyroglobulin and thyroid peroxidase autoantibodies) in 70 children (32 M and 38 F) with DS, mean age 10.5 y (range 1-19 y). Twenty-seven (39%) of the patients were found to have thyroid autoantibodies, the prevalence of antibody positivity increasing with age. Of the 17 (24%) of the series who were hypothyroid (i.e. high basal TSH level and a low total- or free-T4 level), 11 had thyroid autoantibodies, and another 6 with thyroid autoantibodies became hypothyroid during 13-35 months of follow-up. Thus, the findings suggest that the majority of hypothyroid children with DS suffer from autoimmune thyroid disease.

Prevalence of autoantibodies associated with glomerulonephritis, unaffected after extracorporeal shock wave lithotripsy for renal calculi, in a three-year follow-up

Extracorporeal shock wave lithotripsy (ESWL) has become a useful tool in the treatment of renal calculi, but side effects may occur. Hitherto, two case reports have been published of an anti-glomerular basement membrane disease resulting in end-stage renal failure following ESWL treatment. In this prospective study of 59 consecutive patients undergoing ESWL for renal calculi, the prevalence of autoantibodies associated with glomerulonephritis was investigated before ESWL and at 3-year follow-up. The prevalences of antinuclear, anti-glomerular basement membrane, anti-neutrophil cytoplasmic and thyroid antibodies were found to be within the respective normal ranges prior to the first ESWL treatment and to be unaffected at follow-up.

Human thyroglobulin reference material (CRM 457). 2nd Part: Physicochemical characterization and certification

This report describes the characterization of a purified human thyroglobulin (Tg) reference material, and details the procedures used in its certification. The purified Tg is intended to be used as a primary reference material to establish calibration of working serum based reference material for immunoassay procedures. The programme involved the participation of 15 European laboratories and one laboratory from the United States. The physicochemical characterization showed by polyacrylamide gel electrophoresis and immunoblotting that the purified Tg had for the major part the expected molecular size of 660 kDa with traces of lower molecular forms. The amino acid composition was close to that demonstrated for the cDNA and the content of iodine was in keeping with a moderately to highly iodinated Tg. The mass concentration in reference material RM 457 is certified to be (0.324 +/- 0.018) g/L on the basis of protein determined by the Lowry method and supported by nitrogen determination, absorbance measurement, and amino acid analysis. This reference material is considered the first step towards decreasing the interlaboratory variability between Tg methods of measurement.

Human thyroglobulin reference material (CRM 457). 1st Part: Assessment of homogeneity, stability and immunoreactivity

This paper describes the assessment of the homogeneity and stability of a purified and lyophilized human thyroglobulin (Tg), and characterizes its immunoreactivity. The purified and lyophilized Tg is intended to be used as a primary reference material to establish calibration of working serum based reference material. The programme involved the participation of 15 European laboratories and one laboratory from the United States. The homogeneity of the content of the ampoules was considered acceptable (< 9%). The stability was tested by accelerated temperature degradation showing predicted annual relative losses of 0.01% at -70 degrees C and 1.04% at -20 degrees C. The immunoreactivity of the Tg material as measured in different laboratories varied mostly according to the method used rather than the laboratory. The interlaboratory variability showed that the two commercial methods used in several laboratories (kit 1 and 2) had an interlaboratory variation (CV) of 15.9% (N = 5) and 7.1% (N = 3), respectively, whereas the total interlaboratory CV was 64.3% (N = 18). The immunoreactive Tg had dilution curves parallel with other Tg calibrators (those of the methods). Dilution curves of the Tg material after storage at various temperatures and time were parallel in both RIA and IRMA. In conclusion, we have prepared a Tg reference material which in extensive studies in several participating laboratories has demonstrated a sufficient homogeneity and stability as well as dilution curves parallel to the calibrators of all the immunoassays tested in the study. This reference material is considered the first step towards decreasing the interlaboratory variability between Tg immunoassays.

Increased incidence of thyrotoxicosis in Malmö during the years 1988-1990 as compared to the years 1970-1974

OBJECTIVE AND DESIGN

To compare the total and age-specific incidence of thyrotoxicosis, as well as the incidence of the individual types of thyrotoxicosis [i.e. thyrotoxicosis of Graves' type (GD), toxic nodular goitre (TNG) and solitary toxic adenoma (STA)] in Malmö during the years 1988-1990 to those of a previous study in 1970-1974.

SETTING

The town of Malmö in southern Sweden.

SUBJECTS

All patients from the Malmö population treated for thyrotoxicosis (GD, TNG and STA) for the first time during the 3-year period 1988-1990 were included.

RESULTS

Overall, 299 (263 females and 36 males) new cases of thyrotoxicosis were diagnosed in 1988-1990, corresponding to a mean annual incidence of thyrotoxicosis of 43.0 per 100,000 inhabitants. The incidence of GD was 22.3, of TNG 16.0 and of STA 4.8 per 100,000 per year. Comparing age- and sex-standardized incidences to the results in 1970-1974, there was a significant increase (P < 0.001) in the mean annual incidence of thyrotoxicosis in the total material as well as in TNG. In addition, there was an increase in GD in females younger than 50 years (P < 0.01), whereas in TNG/STA, an increase was seen in females of 50 years or older (P < 0.001). The incidence figures in males were not significantly changed. There was a higher proportion of smokers in females with GD compared to females with TNG (P < 0.001) and STA (P < 0.05).

CONCLUSIONS

The total incidence of thyrotoxicosis, as well as the incidence of GD in females younger than 50 years and the incidence of TNG/STA in females of 50 years or older, has increased in Malmö during the period from 1970 to 1990. The increase was probably caused by several factors such as more sensitive diagnostic tools and GD changes in smoking habits, but additional unknown factors might also be of importance.

Thyroid antibodies are not a risk factor for pregnancies with Down syndrome

The observation that thyroid disease is frequent in mothers of children with Down syndrome (DS) has suggested that maternal thyroid antibodies could be a factor predisposing to trisomy 21 in their offspring. In this study, the incidences of thyroglobulin (Tg) and thyroid peroxidase (TPO) antibodies were analysed with a sensitive solid-phase immunosorbent radioassay in sera from 29 mothers giving birth to children with trisomy 21 and 87 control mothers. The serum samples were collected at delivery. There was no statistical difference regarding the proportion of thyroid antibodies (against Tg and/or TPO) in the two groups. Thyroid antibodies were detected in 6/29 (20.7 per cent) of the DS mothers and in 23/87 (26.4 per cent) of the control mothers. Among the women with thyroid antibodies, 4/6 (66.7 per cent) of the DS mothers and 12/23 (52 per cent) of the control mothers had antibodies against both Tg and TPO. There was no increase in the relative risk of having a child with DS if the titre of either Tg or TPO antibodies or both were positive, i.e. > or = 1/5. The results indicate that the presence of thyroid antibodies in the serum of a pregnant women has no prognostic value for the birth of an infant with DS.

Effect of acute desmopressin and of long-term thyroxine replacement on haemostasis in hypothyroidism

OBJECTIVE

Hypothyroidism can be complicated by bleeding symptoms such as easy bruising, menorrhagia and sometimes even a severe bleeding tendency with fatal outcome. Usually there is a prolonged bleeding time, or a low plasma concentration of coagulation factor VIII (FVIII) or von Willebrand factor (vWF). The aim of the present study was to investigate the acute haemostatic effect of desmopressin in hypothyroid patients. Another aim was to study the long-term effect of thyroxine replacement on the plasma concentrations of coagulation factors and to ascertain the duration of thyroxine treatment needed to restore haemostatic function.

DESIGN AND PATIENTS

The effects of desmopressin, given intravenously over 10 minutes at a dosage of 0.3 micrograms/kg, and thyroxine treatment on haemostatic function were studied prospectively in 10 patients with hypothyroidism.

RESULTS

Before treatment only five of the patients manifested bleeding symptoms; one had prolonged bleeding time, and one had low plasma concentrations of vWF:Ag. Desmopressin virtually immediately reduced bleeding time, enhanced platelet adhesiveness, and significantly increased plasma concentrations of FVIII and vWF. The plasma concentrations of FVIII and vWF showed a significant increase after 4 months, whereas 7 months treatment with thyroxine was needed to reduce bleeding time significantly.

CONCLUSION

Our results suggest that in hypothyroid patients desmopressin may be of value for the acute treatment of bleeding or as cover for surgery.

Thyroid autoantibodies, Turner's syndrome and growth hormone therapy

The prevalence of thyroid autoantibodies, i.e. thyroglobulin antibodies and antibodies to thyroid peroxidase, was analyzed in 89 girls, aged 3-16 years (mean age 10 years), with Turner's syndrome. The analyses were performed before the start of growth-promoting treatment and during a follow-up period of 1-5 years. The patients were divided into four groups according to karyotype as follows: group 1, 45, X (n = 63); group 2 with structural abnormalities of the X chromosome (n = 10); group 3 with mosaicism but no structural abnormalities of the X chromosome (n = 10); and group 4, with isochromosome X of the long arm (n = 12): 199 healthy girls aged 12 years, served as controls. Thyroid autoantibodies were demonstrated in 46 of 89 (52%) patients with Turner's syndrome compared with 34 of 199 (17%) age-matched control girls (p < 0.001), thus confirming the relationship between thyroid abnormalities and Turner's syndrome. There was also an increase in the prevalence of thyroid antibodies with age. Simultaneous presence of both autoantibodies was significantly more frequent in group 1 (45, X) and group 4 (isochromosome X of the long arm) than in group 3 (mosaicism) (p = 0.04 and p < 0.002, respectively) and significantly more frequent in group 4 than in group 1 (p < 0.05). During 12-60 months of growth-promoting treatment, no increase in the prevalence of thyroid antibodies was observed. The findings demonstrate the importance of continuous monitoring of thyroid function in girls with Turner's syndrome.

Serum selenium concentrations in patients with autoimmune thyroiditis and non-toxic nodular goiter

Selenium (Se) deficiency is said to contribute to the atrophy of the thyroid gland in certain endemic goiter areas in Africa. To test the hypothesis that, a low Se intake could protect against goiter development in autoimmune thyroiditis, we analysed the Se concentration in 20 patients with the atrophic variant of lymphocytic thyroiditis, 23 patients with Hashimoto's thyroiditis and 23 patients with non-toxic nodular (colloid) goiter. Twenty healthy females served as controls. We did not find any significant difference in serum selenium (S-Se) levels between the patients with the various thyroid disorders or between patients and controls. There was no difference in the S-Se concentration and the triiodothyronine (T3), thyroxine (T4), thyrotropin (TSH) or thyroglobulin concentrations in serum. Thus, the Se status had no impact on the development of goiter.

Basal and thyrotropin-stimulated secretion rates of thyroglobulin from the human thyroid gland during surgery

The secretion rates of thyroglobulin were measured under basal conditions and after exogenous and endogenous thyrotropin stimulation in 23 patients during surgery. In 11 patients with normal thyroid glands the median secretion rate of thyroglobulin was 0.7 pmol/24 h. Higher secretion rates were observed in 8 patients with nontoxic nodular goiter (median 22 pmol/24 h; p < 0.001) and in 4 patients with thyroid malignancy (median 2.2 pmol/24h; p < 0.05). Within 10 min after administration of highly purified human thyrotropin into the thyroid artery an increase of the secretion rates was observed in the 9 patients studied with normal thyroid glands and 5 patients with nontoxic nodular goiter. TRH administration to 5 patients induced a slight but nonsignificant increase of the secretion rate of thyroglobulin after 20 min. These results show that thyroglobulin is secreted directly into the thyroid venous blood. They also confirm that thyrotropin is an important regulator of the thyroglobulin secretion.

Tongue necrosis in temporal arteritis provoked by ergotamine

A case of tongue necrosis in a patient with temporal arteritis who was taking ergotamine is described, and the role of ergotamine tartrate in provoking the tongue necrosis is considered. The literature on this unusual complication is critically reviewed, and the value of a carotid angiography in assessing the tongue ischaemia is exemplified.

The role of estrogen in the TSH and prolactin responses to thyrotropin-releasing hormone in postmenopausal as compared to premenopausal women

The basal and TRH (Thyrotropin-Releasing Hormone) stimulated TSH (Thyrotropin) and PRL (Prolactin) responses (incremental area; IA) to 200 micrograms TRH was studied in 13 pre- and 13 postmenopausal women of 60 years of age. Both groups consisted of healthy women, none had goiter and all were negative for thyroid autoantibodies. The serum levels of TSH, T3, T4 and SHBG (sex hormone-binding globuline) were in the normal range and did not differ significantly between the groups. There were no differences in basal TSH (1.3 +/- 0.5 vs 1.4 +/- 0.5 mIU/l) or PRL (6.4 +/- 2.7 vs 6.6 +/- 2.5 micrograms/l) or for PRL IA (498 +/- 126 vs 584 +/- 165) between pre- and postmenopausal women. However, for TSH IA there was a slight decrease (15%), but not significant, in the postmenopausal group compared to the premenopausal group (1630 +/- 598 vs 2067 +/- 893). In conclusion, a weak but not significant decrease in the TSH response to TRH in postmenopausal women may be explained by the lower endogenous estradiol level.

Salivary gland involvement in autoimmune thyroiditis, with special reference to the degree of association with Sjögren's syndrome

From a total of 63 patients with autoimmune thyroiditis, 19 cases were further investigated to determine the degree of concomitant morphologic and functional salivary gland changes. For comparison, 21 of a total of 28 cases of primary Sjögren's syndrome were also examined. Of the 19 cases of autoimmune thyroiditis, 11 showed various degrees of salivary gland involvement on the basis of an analysis of lower lip salivary gland biopsy specimens, scintigraphy of the parotid, and unstimulated whole sialometry. Six of these cases fulfilled the criteria of primary Sjögren's syndrome. A remarkably high proportion of dark-staining acini was observed in the lower lip biopsy specimens of our patients with thyroiditis (8 of 19, 42%) and less among our patients with primary Sjögren's syndrome (5 of 21, 24%). We conclude that significant involvement of salivary glands may occur in cases of autoimmune thyroiditis, which indicates that common mechanisms may frequently be operative in the development of thyroid and salivary gland immune disease.

Leukaemia incidence after iodine-131 exposure

Leukaemia is one of the most prominent late effects of exposure to ionising radiation. We have studied the incidence of leukaemia among 46,988 Swedish patients exposed to iodine-131 (131I) for diagnostic reasons or to treat hyperthyroidism or thyroid cancer. The observed number of leukaemias was compared with that expected based on incidence data from the general population. The mean absorbed dose to the bone marrow was estimated as 14 mGy (range 0.01-2.226). 195 leukaemias occurred more than 2 years after exposure, and the standardised incidence ratio (SIR) was 1.09 (95% confidence interval 0.94-1.25). Similar, but again not significantly, increased risks were seen for chronic lymphocytic leukaemia (CLL) (SIR = 1.08), a malignant condition not found to be increased after irradiation, and for non-CLL (SIR = 1.09). The risk of leukaemia did not vary by sex, age, time, or radiation dose from 131I. One reason for the absence of a radiation effect, other than chance, includes the possible lowering of risk when exposure is protracted over time as occurs with 131I. Excess leukaemia risks of more than 25% could thus be excluded with high assurance in this population of mainly adults. These results should be reassuring to patients exposed to 131I in medical practice and to most individuals exposed to the fall-out from the Chernobyl accident.

Cancer mortality after iodine-131 therapy for hyperthyroidism

Cancer mortality was studied in 10,552 Swedish hyperthyroid patients treated with 131I between 1950 and 1975. The patients were matched with the Swedish Cause-of-Death Register and the cases of 977 patients who died from cancer or leukemia were studied. The patients had been followed up for an average of 15 years (range 0 to 35 years), and the overall standardized mortality ratio (SMR) was 1.09 [95% confidence interval (CI) = 1.03 to 1.16], with a higher risk for women. The highest mortality was seen during the first year after exposure (SMR = 1.15) and decreased for the following 9 years (SMR = 1.04). The risk of dying from a cancer in the digestive tract and respiratory organs was significantly elevated more than 10 years after exposure, as was the overall cancer mortality (SMR = 1.14). No increased risk was seen for leukemia, bladder cancer or breast cancer. Younger patients and those receiving 131I at higher activity had higher SMRs than older patients and those receiving lower activity. Patients with toxic nodular goiter had higher risk than those with Graves' disease. The lack of increasing mortality over time and with increasing activity of 131I administered argues against a carcinogenic effect of 131I. However, in the case of cancers of the stomach, the 131I exposure could have contributed to the excess mortality from these cancers.

Cancer risk after iodine-131 therapy for hyperthyroidism

Cancer incidence was studied in 10,552 patients (mean age, 57 years) who received 131I therapy (mean dose, 506 MBq) for hyperthyroidism between 1950 and 1975. Follow-up on these patients was continued for an average of 15 years. Record linkage with the Swedish Cancer Register for the period 1958-1985 identified 1543 cancers occurring 1 year or more after 131I treatment, and the standardized incidence ratio (SIR) was 1.06 (95% confidence interval = 1.01-1.11). Significantly increased SIRs were observed for cancers of the lung (SIR = 1.32; n = 105) and kidney (SIR = 1.39; n = 66). Among 10-year survivors, significantly elevated risks were seen for cancers of the stomach (SIR = 1.33; n = 58), kidney (SIR = 1.51; n = 37), and brain (SIR = 1.63; n = 30). Only the risk for stomach cancer, however, increased over time (P less than .05) and with increasing activity administered (P = not significant). The risk for malignant lymphoma was significantly below expectation (SIR = 0.53; n = 11). Overall cancer risk did not increase with administered 131I dose or with time since exposure. The absence of any increase in leukemia adds further support to the view that a radiation dose delivered gradually over time is less carcinogenic than the same total dose received over a short time. Only for stomach cancer was a possible radiogenic excess suggested.

Autoimmune thyroiditis and primary Sjögren's syndrome: clinical and laboratory evidence of the coexistence of the two diseases

The prevalence of primary Sjögren's syndrome (primary SS) among patients with autoimmune thyroiditis (AT), and that of AT among patients with primary SS were studied prospectively. Of 63 patients with AT, one had precipitating antibodies against SS-A/Ro antigen together with objectively verified primary SS, and none had precipitating anti-SS-B/La antibodies; in contrast 17/63 (27%) had above normal values of anti-SS-B/La antibodies, as tested with ELISA. Of 19 AT patients tested objectively for xerostomia and keratoconjunctivitis sicca, six (32%) had keratoconjunctivitis sicca together with xerostomia and four (21%) had autoimmune sialadenitis. The prevalence of AT in patients with primary SS (n = 28) was 18%; of the 28 patients, 64% had an enlarged or abnormal thyroid gland on palpation and four of them (14%) had cytology verified AT. Ten (36%) had anti-thyroglobulin and/or antimicrosomal autoantibodies. Based upon the present investigation we conclude that the prevalence of primary SS is ten times higher among patients with AT, and that of AT is nine times higher among patients with primary SS, compared with the general population.

Effects of cigarette smoking on thyroid function and the prevalence of goitre, thyrotoxicosis and autoimmune thyroiditis

The effect of smoking habits on thyroid function and the prevalence of thyroid diseases was studied in two birth cohorts (1928 and 1941) of men and women. A total of 1555 individuals (836 men and 719 women) were smokers. 1048 individuals (604 men and 444 women) were ex-smokers and 1497 individuals (560 men and 937 women) were non-smokers. The serum thyrotropin (TSH) concentration was significantly lower in smokers than in ex-smokers and non-smokers (P = 0.05 and P = 0.001, respectively). Smoking habits did not affect the serum triiodothyronine (T3) concentrations. The prevalence of non-toxic goitre and toxic diffuse goitre was significantly higher in smoking women than in non-smoking women (P = 0.005 and P = 0.04, respectively). Thiocyanate may be the goitrogenic factor responsible for the increased prevalence of non-toxic goitre. The cause of the increased prevalence of toxic diffuse goitre is less obvious. Hypothetically, an increase in sympathetic activity in smokers may promote the development of thyrotoxicosis in predisposed individuals, but immunological disturbances caused by smoking are another possibility.

The value of neonatal serum thyroglobulin determinations in the follow-up of patients with congenital hypothyroidism

Serum thyroglobulin was determined in 68 newborn infants with positive screening tests for congenital hypothyroidism. In 38 infants the diagnosis was confirmed (patients), but the remaining 30 were euthyroid at follow-up (controls). The mean thyroglobulin concentration at the age of 2 weeks did not differ significantly between the patients and the controls (179 vs. 125 micrograms/l). Thyroid scintigraphy was performed in 15 patients. All seven with thyroid aplasia, based on 99mTc pertechnetate scintigraphy, had measurable thyroglobulin (greater than 2 micrograms/l) and thyroid hormones in their serum. This indicates that total absence of thyroid tissue is very rare in Swedish patients with congenital hypothyroidism. Scintigraphy based on 99mTc does not permit detection of small amounts of thyroid tissue. The neonatal concentrations of thyroglobulin did not correlate with the results of Griffiths test at 3 years and are therefore not useful for prognosis of psychomotor development. We conclude that neonatal measurement of thyroglobulin is of limited value in the follow-up of patients with congenital hypothyroidism.

The epidemiology of thyroid disorders in a seaport community in southern Sweden

The prevalence of thyroid disorders was studied in two birth cohorts (1928 and 1941) of men and women living in Malmö, a non-iodine deficient area. In the 1928 cohort, the prevalence of thyroid disorders was 11.5% overall (mean 2.4% , women 20.3%), and higher among immigrant women (20.7%) than among women of the native population, e.g. women born in and still living in Malmö (14.7%). In the 1941 cohort, the overall prevalence of thyroid disorders was 7.9% (men 1.5%, women 14.1%); and the prevalence of goiter was lower among immigrant women (9.5%) than among women of the native population (15.0%). Among the native population, the prevalence of goiter did not differ significantly between the two cohorts, whereas among immigrant women it was significantly greater in the 1928 cohort. The findings suggest that, although iodine deficiency is the most probable cause of goiter among immigrants of the 1928 cohort, where the native population is concerned (both men and women), some other goitrogenic factor(s) must be involved.

Ultrasonic imaging in the differential diagnosis of diffuse thyroid disorders in children

In 22 patients with suspected diffuse goiter, the diagnostic accuracy of ultrasonography was compared with that of aspiration biopsy cytology and thyroid antibody testing. Ultrasonography was abnormal in 100% (10/10) of the patients with autoimmune thyroid disease, only 90% (9/10) of whom were identified with antibody testing. All patients with diffuse colloid goiter had normal echo patterns on ultrasound imaging, whereas 29% (2/7) of them had positive results on antibody testing. Whether these are 'false positives' or represent focal thyroiditis remains unclear. Thus, ultrasound imaging stands out as a valuable diagnostic tool for the differential diagnosis of diffuse thyroid disorders in children.

Cancer risk in population examined with diagnostic doses of 131I

Previously, we conducted a study of 35,074 patients receiving diagnostic doses of 131I for suspected thyroid disorders between 1951 and 1969. We reported that, between 1958 and 1984, the incidence of thyroid cancers in these patients was insignificantly greater than the incidence expected in the general population. This increase was attributed to the underlying condition that prompted the examination and not to the administration of 131I. The purpose of the present study was to analyze the total cancer risk in the same cohort of patients examined with diagnostic doses of 131I. To further evaluate the underlying risk of disease in these patients, we compared the incidence of all cancers with that expected in the general population. The average radiation dose was approximately 500 mGy to the thyroid and less than 10 mGy to other organs. In the 35,074 patients, 3,746 cancers occurred following the first 5 years after examination, and the resulting standardized incidence rate (SIR) was 1.01 (95% confidence interval = 0.98-1.04). SIRs were significantly increased for endocrine tumors other than thyroid cancer (1.93) and for lymphomas (1.24), leukemias (1.34), and nervous system tumors (1.19). The risk of leukemia was similar for chronic lymphocytic leukemia (CLL) (SIR = 1.30) and non-CLL (SIR = 1.34). SIR was significantly decreased for cancers of the female genital organs (0.86). The risk for cancer of all sites and types combined was highest 5-9 years after examination (SIR = 1.07) and did not differ from unity thereafter. With greater than or equal to 10 years of follow-up, risk was not statistically associated with the dose of 131I. Overall, the data exclude cancer risk increments greater than 5% (SIR = 1.05) with 95% confidence. The significant increase in the risk of non-CLL, a prominent radiogenic malignancy, however, warrants special attention. We are continuing our study to determine the possible factors involved in the significant increase in the risk of leukemia.

Thyroid cancer after diagnostic doses of iodine-131: a retrospective cohort study

The incidence of thyroid cancer was evaluated in 35,074 patients examined for suspected thyroid disorders between 1951 and 1969 with an average of 1.92 megabecquerel [(MBq) 52 microCi] of 131I. The radiation dose to the thyroid gland was, on the average, approximately 0.5 Gy. The mean age at the time of examination was 44 years; 5% were under age 20. Patients were followed for an average of 20 years. Record linkage with the Swedish Cancer Register identified 50 thyroid cancers occurring 5 years or more after the initial 131I examination, in contrast to 39.4 expected based on general population rates [standardized incidence ratio (SIR) = 1.27, 95% confidence interval = 0.94-1.67]. Risk was highest among males (SIR = 2.70, n = 10), patients followed 5-9 years (SIR = 2.22, n = 23), and patients receiving more than 74 microCi or 2.74 MBq of 131I (SIR = 2.04, n = 17). However, these observations were confounded by the fact that patients examined for a suspected thyroid tumor received the highest 131I exposures and were at highest overall risk (SIR = 2.77, n = 34). Patients given 131I for reasons other than a suspected tumor were not at increased risk (SIR = 0.62, n = 16). Patients anticipated to be at highest risk, i.e., women (SIR = 1.12, n = 40) and those observed for 10 years or more (SIR = 0.93, n = 27), showed no evidence of a dose response. Overall, these data provide little proof that 131I is carcinogenic in humans and support the notion that the carcinogenic potential of internal 131I beta particles might be as low as four times less than external x rays or gamma rays.

Endogenous antibodies to bovine lactoperoxidase in children and adolescents

Sera from 146 children and adolescents (70 girls and 76 boys, median age 6 years; range 8 months - 18 years) were analysed for the presence of antibodies to bovine lactoperoxidase (LPO) using a solid-phase immunosorbent radioassay. LPO antibodies were present in all but one serum. The antibody titres varied from 1/5 to greater than 1/5000 (final dilutions). Most of the individuals had antibody titres between 1/50 to 1/5000. Because of the frequent occurrence of LPO antibodies in human beings, the presence of LPO antibodies in the serum must be regarded as a physiological phenomenon.

Effect of therapy on the serum thyroglobulin concentration in patients with toxic diffuse goiter, toxic nodular goiter and toxic adenoma

Serum thyroglobulin (S-Tg) was measured in 104 patients with thyrotoxicosis, 59 of whom had toxic diffuse goiter (Graves' disease), in 30 with toxic nodular goiter and in 15 with toxic adenoma. Before treatment, most patients had increased S-Tg concentrations, regardless of what type of thyrotoxicosis they had. After therapy the course of the S-Tg varied, two major patterns being observed: the S-Tg concentration increased in some patients but decreased in others, although no relationship could be found between these patterns and the outcome of therapy, the presence or absence of thyroglobulin antibodies (Tg-ab) or changes in the Tg-ab titer. However, the median pretreatment concentrations of S-Tg were significantly higher in patients with toxic nodular goiter and toxic adenoma than in those with toxic diffuse goiter (p less than 0.001 and p less than 0.05, respectively), but did not differ significantly between patients with toxic nodular goiter and toxic adenoma. The lowest posttreatment S-Tg concentrations were found after surgery, irrespective of type of thyrotoxicosis. The median pretreatment and posttreatment S-Tg concentrations in patients with toxic diffuse goiter who relapsed, did not differ from those patients in remission. This was also true of patients with toxic nodular goiter. In both groups, however, there was a tendency towards higher pretreatment S-Tg values in patients who subsequently relapsed. Serial determinations of S-Tg, on the other hand, are of limited value in predicting the risk of recurrence, independent of which type of thyrotoxicosis is involved.

Evaluation of the usefulness of a sensitive immunoradiometric assay for thyroid stimulating hormone as a first-line thyroid function test in an unselected patient population

A new sensitive immunoradiometric assay for serum thyroid stimulating hormone (TSH) was applied to 1627 consecutive patients from four large clinics at Malmö General Hospital, in whom a thyroid function disorder was suspected. The final diagnoses were taken from the patients' charts at a follow-up 1-2 years after the primary evaluation. If only those patients without thyroid disease were used as a reference population, the 5th percentile was 0.8 mIU/l. When this cutoff limit was applied to the unselected patient population, the TSH assay had a high sensitivity for the diagnosis of hyperthyroidism (96%), a lower specificity (64%) and a very low predictive value (10%). Therefore, in the majority of the patients (72%) the sensitive TSH assay cannot be used alone to define thyroid function.

Thyroglobulin in cord blood. The influence of the mode of delivery and the smoking habits of the mother

The cord thyroglobulin (Tg) concentration was estimated in 160 full-term newborns of whom 103 were delivered normally, 26 by elective Cesarean section and 31 by vacuum extraction. There was no correlation between the median cord Tg concentration and gestational age at delivery (37-43 weeks), birth weight or sex of the child or the median cord TSH concentration. The median cord Tg concentration was significantly higher in the children born by Cesarean section than in those delivered by vacuum extraction (P less than 0.001). The same tendency was found when smokers and non-smokers were compared separately. Mechanical force on the thyroid gland during labour and delivery therefore does not seem to increase the cord Tg concentration. The influence of maternal cigarette smoking on the cord Tg concentration was studied also. Forty-five mothers were smokers. The median cord Tg concentration in the children of these women was significantly higher than in the children of non-smoking mothers (130 micrograms/l vs 100 micrograms/l, P less than 0.001), whereas the median cord TSH concentration did not differ between these groups. It therefore seems possible that components of cigarette smoke, e.g. thiocyanate, may have a direct effect on the thyroid gland of the fetus.

A high prevalence of thyroglobulin autoantibodies in adults with and without thyroid disease as measured with a sensitive solid-phase immunosorbent radioassay

Sera from 228 patients with thyroid disease and 140 healthy subjects without clinical or biochemical evidence of thyroid disease, were tested using a sensitive solid-phase immunosorbent radioassay (RIA) and a passive hemagglutination test (TRC test) for thyroglobulin antibodies (Tg-ab). With the RIA technique, Tg-ab was found in 27% of the controls (36% of the women and 15% of the men), whereas only 0.7% of them were Tg-ab positive with the TRC test. All individuals with primary hypothyroidism were Tg-ab positive with the RIA, compared with only 56% with the TRC test. Tg-ab (RIA) were found in 43/53 (81%) of the patients with toxic diffuse goiter, and in 30-40% of the patients with toxic nodular goiter, toxic adenoma, atoxic goiter, and thyroid carcinoma, the TRC test being positive in 10-17% of these patients. The high prevalence of Tg-ab in the healthy population suggests that subclinical thyroiditis is more frequent than has been assumed from antibody measurements made with less sensitive methods, and is in agreement with the prevalences reported from autopsy studies.

Thyroglobulin and thyroid hormones in patients on long-term treatment with phenytoin, carbamazepine, and valproic acid

Serum concentrations of total triiodothyronine (T3) and thyroxine (T4) as well as serum thyroid-stimulating hormone (TSH) and thyroglobulin (Tg) were measured in 24 patients with epilepsy taking anticonvulsants (either phenytoin, carbamazepine, or valproic acid as single treatment) and in a control group of 28 patients with scoliosis but without thyroid disease. The T4 as well as the TSH concentrations were depressed in patients on phenytoin or carbamazepine treatment. The T3 concentration was increased in the patients on carbamazepine or valproic acid treatment, whereas the Tg levels were unaffected by all three drugs. Thus, a slight depression of the TSH concentration within the normal range does not influence the Tg release. The lack of change in the Tg concentration also speaks against a direct effect of the antiepileptic drugs on the thyroid gland.

Interference of endogenous lactoperoxidase antibodies in a solid-phase immunosorbent radioassay for antibodies to protein hormones

Interference of endogenous antibodies to lactoperoxidase (EC 1.11.1.7) has been demonstrated in a solid-phase immunosorbent radioassay for the detection of antibodies to protein hormones. On enzymic iodination with lactoperoxidase, a little of the 125I is incorporated in the enzyme itself by self-iodination. Because the 125I-labeled lactoperoxidase was not removed from the tracer by chromatography on Sephadex G-50, G-100, and G-200 columns, endogenous antibodies to the enzyme, which were present in 25 of 28 sera from apparently healthy individuals, were detected in conjunction with the measurement of antibodies to growth hormone (somatotropin), prolactin, and thyroglobulin, thus causing false-positive results. Contaminating radioactive lactoperoxidase can be removed by adsorption chromatography on cellulose or by liquid chromatography, and can be avoided by performing the iodination with immobilized lactoperoxidase or with Chloramine-T.

Interference of endogenous lactoperoxidase antibodies in a solid-phase immunosorbent radioassay for antibodies to protein hormones

Interference of endogenous antibodies to lactoperoxidase (EC 1.11.1.7) has been demonstrated in a solid-phase immunosorbent radioassay for the detection of antibodies to protein hormones. On enzymic iodination with lactoperoxidase, a little of the 125I is incorporated in the enzyme itself by self-iodination. Because the 125I-labeled lactoperoxidase was not removed from the tracer by chromatography on Sephadex G-50, G-100, and G-200 columns, endogenous antibodies to the enzyme, which were present in 25 of 28 sera from apparently healthy individuals, were detected in conjunction with the measurement of antibodies to growth hormone (somatotropin), prolactin, and thyroglobulin, thus causing false-positive results. Contaminating radioactive lactoperoxidase can be removed by adsorption chromatography on cellulose or by liquid chromatography, and can be avoided by performing the iodination with immobilized lactoperoxidase or with Chloramine-T.

Purification and storage of thyroglobulin. Two important factors influencing the radioimmunoassay for thyroglobulin

The effect upon the assay of the quality of the thyroglobulin (Tg) used as standard and tracer was evaluated by comparison of two preparations, one purified with protease inhibitors added (Tg-PI) and the other without (Tg-O). Tg-PI proved more stable than Tg-O. After freezing in phosphate-buffered saline almost all 125I-Tg-O was found to have dissociated into 12 S Tg, while only about half the 125I-Tg-PI had done so. Storage in glycerol, 500 g/l, at -20 degrees C or freezing in goat serum improved the quality of the 125I-Tg markedly, but Tg-PI still remained more stable than Tg-O. In addition, the two antisera tested gave different results in the radioimmunoassay with Tg-PI and Tg-O. With one antiserum a gradual loss of Tg immunoreactivity occurred parallel to the dissociation of Tg, while no such effect was noted with the other antiserum. This difference is believed to depend on varying proportions of conformational antibodies in the antisera, the binding sites for the conformational antibodies being distorted by the dissociation of the Tg molecule, while the binding sites for the sequential antibodies remain intact.

A new sensitive immunosorbent radioassay for the detection of circulating antibodies to polypeptide hormones and proteins

A solid-phase immunosorbent radioassay for the detection of circulating antibodies to protein hormones is described. The assay is based on the binding of the homologous 125I-labelled antigen to the antibodies which are then bound to anti-IgG antibodies covalently coupled to Sepharose. It can easily be applied as a complement to any radioimmunoassay for the detection of circulating antibodies to the ligand measured. The assay system avoids falsely elevated values due to interference of high serum concentrations of the antigen. The assay was applied to measure antibodies to FSH, LH, TSH, GH, prolactin, insulin and thyroglobulin (Tg). Among patients with chronic thyroiditis Tg antibodies were found in 100% of the sera. In diffuse toxic goitre 73% of the patients had detectable Tg antibodies. Insulin antibodies were present in 82% of the sera from patients with insulin treated diabetes. No antibodies were found against the other protein hormones tested.

Influence of cigarette smoking on goiter formation, thyroglobulin, and thyroid hormone levels in women

The possible influence of cigarette smoking on goiter formation, thyroglobulin (Tg) secretion, and thyroid hormone production was assessed by estimations of the presence of palpable goiter and by RIAs of Tg, T3, rT3, T4, and TSH in sera from 441 women (48-53 yr old), representing a normal population included in a study on the prevalence of thyroid disease. Smoking habits were evaluated by a questionnaire, and the women were then classified as never smokers (n = 192), smokers (n = 169), and exsmokers (n = 80). Smokers were subdivided as moderate (1-19 cigarettes/day) and heavy (greater than or equal to 20 cigarettes/day). Palpable goiter was found in 15% of the smokers, in contrast to only 4% of the exsmokers and 9% of the never smokers. Among smokers, 37% had serum Tg values over 30 micrograms/liter (third quartile), while such values were found in only 16% of the exsmokers and 18% of the never smokers. In addition, smokers were found to have higher serum T3 and lower rT3 concentrations than never smokers; this difference was most pronounced in heavy smokers. Serum T4 was not different, while TSH was insignificantly lower in smokers than in nonsmokers. Exsmokers did not differ significantly from never smokers in any of these parameters. It seems possible that cigarette smoking may have two, calorigenically opposed, effects on thyroid hormone production; it may be goitrogenic (possibly due to inhaled thiocyanate), but it may also enhance the formation of T3 at the expense of rT3 formation.

A compound follicular-parafollicular cell carcinoma of the thyroid: a new tumor entity?

An unusual thyroid carcinoma is described, showing structural, histochemical and radioimmunologic features of both a follicular and a parafollicular cell carcinoma. Radioimmunoassay revealed high levels of thyroglobulin in the patient's serum and in extracts from metastatic tumor tissue. Immunoreactive thyroglobulin was demonstrated histochemically in tumor cells. On scanning, pulmonary metastases showed uptake of 131I. Somatostatin and neurotensin immunoreactivity was also revealed histochemically in the tumor and a large proportion of the neoplastic cells were argyrophil. Serum calcitonin level was normal and no immunoreactive calcitonin was found in tumor tissue by radioimmunoassay or histochemically. Light microscopy showed cribriform patterns suggestive of follicular carcinoma as well as solid areas reminiscent of medullary carcinoma. Electron microscopy revealed two types of tumor cells. One type had electron dense granules resembling secretory granules characteristic of polypeptide hormone and/or monoamine producing endocrine cells. The other type had no such granules but showed a prominent vesicular rough endoplasmic reticulum similar to that seen in neoplastic follicular cells. The results suggest two alternative possibilities regarding the histogenesis of the tumor. One would be a mixed neoplasm, resulting from a coincidental malignant change in both follicular and parafollicular thyroid cells. The other, more likely alternative would be that the tumor cells are derived from a common stem cell with the potentiality of differentiating into both follicular and parafollicular adult cells. The finding that both thyroglobulin and somatostatin or neurotensin immunoreactivity occurred together in some tumor cells supports the latter possibility and suggests that at least some follicular and parafollicular cells may have a common precursor origin.