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Natural history of thyroid abnormalities: prevalence, incidence, and regression of thyroid diseases in adolescents and young adults.

PURPOSE: This study reports the prevalence, incidence, and regression of thyroid abnormalities in a population observed from adolescence to adulthood. PATIENTS AND METHODS: Examinations for thyroid abnormalities were performed in 4,819 school-age children, ages 11 to 18, in 1965 to 1968; two thirds of this original cohort (3,121) were re-examined 20 years later (1985 to 1986). Each subject with a thyroid abnormality detected by physical examination was studied by means of a series of re-examinations, and tests of thyroid function, imaging, and biopsy to determine the exact nature of the thyroid abnormality. RESULTS: In the initial examinations (1965 to 1968), 185 thyroid abnormalities were found (3.7%). Diffuse hypertrophy with normal function (adolescent goiter) was the most common abnormality (19.3/1,000); 12.7/1,000 had chronic lymphocytic thyroiditis, and 4.6/1,000 had thyroid nodules, including two papillary carcinomas. Hyperthyroidism or hypothyroidism was found in 1.9/1,000. In the follow-up examinations in 1985 to 1986, 298 subjects had thyroid abnormalities (10.5%), of whom 81 (28.7/1,000) had simple goiters, 145 (51.3/1,000) had chronic thyroiditis, 45 (15.9/1,000) had hypothyroidism, 11 (3.9/1,000) had hyperthyroidism, and 66 (23.2/1,000) had nodules, which included 10 carcinomas. Of the 92 subjects with simple or adolescent goiter in 1965 to 1968, 60% were normal by 1985 to 1986, 20% were unchanged, and a few had developed thyroiditis (10%) or colloid goiters (3.0%). Of 61 subjects with thyroiditis, 27% had become normal, 33% remained unchanged, and 33% had become hypothyroid. Of the 22 subjects with thyroid nodules, two had complete disappearance of the nodules, and three had nodules considered to be variants of normal. The others exhibited a variety of nodular pathologic conditions. CONCLUSIONS: The natural history of thyroid disorders, including simple goiter, chronic thyroiditis, hyperthyroidism, hypothyroidism, and nodular diseases of the thyroid, indicates they are dynamic and changeable in form, function, appearance, and disappearance.

Adolescent↗

Possible role of genetic factors in thyroid growth rate and in the assessment of upper limit of normal thyroid volume in iodine-replete adolescents.

The objective of this study was to answer the question whether thyroid volume in adolescent siblings of similar age and a life-long sufficient iodine intake is uniform. If different, it would indicate that genetic or environmental factors unrelated to iodine intake can influence thyroid growth. We measured thyroid volume by ultrasound in: (1) 251 sibling pairs (SP) and 19 sibling triads 10 to 18 years of age. The age range of each SP was less than 24 months and of each triad less than 42 months; (2) 28 monozygotic and 13 dizygotic sets of twins 7 to 18 years of age. The sibling pairs were retrospectively divided into 3 groups irrespective of age (thyroid volume as means+/-S.E. mL/m2). Group 1: 159 pairs with low thyroid volume in both siblings; mean thyroid volume of each pair less than 5.00 mL/m2 (3.96+/-0.05, median 4.08, range 2.07-4.98); group 2: 69 pairs with high thyroid volume in both siblings; mean thyroid volume greater than 5.00 mL/m2 (5.85+/-0.12, median 5.57, range 5.03-11.02); group 3: 23 pairs with low thyroid volume in 1 sibling (3.53+/-0.15, median 3.53, range 1.71-4.91) and high thyroid volume in another (7.36+/-0.23, median 7.18, range 5.96-10.30). The majority of triads, monozygotic, and dizygotic twins resembled group 1, a few resembled group 2, and only 3 triads and 1 set of dizygotic twins resembled group 3. Among monozygotic twins, there was no pair with a strikingly discordant thyroid volume and only 1 such pair was found among dizygotic twins. In monozygotic twins, the thyroid volume was almost identical (mean difference 0.34+/-0.06 mL/m2) and significantly less (p < 0.012) than in dizygotic twins (0.9+/-0.25 mL/m2). Among 502 children of 251 sibling pairs the frequency of high thyroid volume (>5.00 mL/m2) was greater in girls (103/279, 36.9%, p < 0.01) than in boys (49/223, 22.0%). The same was true for the frequency of hypoechogenicity (42/279 or 15.0% in girls vs. 12/223 or 5.4% in boys; p < 0.01). The frequency of hypoechogenicity in both sexes of the combined groups 2 and 3 (40/186, 21.5%) was higher (p < 0.001) than in group 1 (14/316, 4.4%). All siblings examined lived in a common household with their parents, eating the same daily meals at home and school. Our results suggest that the observed differences in thyroid volume of siblings were not related to iodine intake, but to other factors, eg, genetic and environmental. It is not clear whether the children with high thyroid volume and increased frequency of hypoechogenicity should be included into the recently recommended range of normal thyroid volume for adolescents.

Adolescent↗

Screening for thyroid disease in a primary care unit with a thyroid stimulating hormone assay with a low detection limit.

In a study at a primary care centre in a predominantly rural area of Sweden the records of all patients with established thyroid disease were scrutinised and 2000 consecutive adult patients screened with an immunoenzymometric thyroid stimulating hormone assay. The aims of the study were fourfold: firstly, to assess the total burden of thyroid disease in primary care centres in Sweden; secondly, to assess the efficacy of clinical diagnosis of the disease in unselected populations of patients; thirdly, to assess the efficacy of clinical evaluation of treatment with thyroxine; and, lastly, to see whether a single analysis of the serum thyroid stimulating hormone concentration by recent methods would be enough to identify an abnormality of thyroid function. Of the roughly 17,400 adults in the study community, 111 women and 10 men were being treated for thyroid disease. Screening detected 68 patients (3.5%) not receiving thyroxine who had a serum thyroid stimulating hormone concentration of 0.20 mU/l or less, all of whom were followed up clinically. Fifty of these patients were also studied biochemically during follow up. Only nine of the 68 patients had thyroid disease (three with thyrotoxicosis requiring treatment), no evidence of the disease being found in the remainder. Sixteen patients had spontaneous hypothyroidism requiring treatment, and neither these nor three patients with thyrotoxicosis had been detected at the preceding clinical examination. Of 35 patients in whom thyroid disease was suspected clinically at screening, none had laboratory evidence of thyroid dysfunction. In this series 1.3% of all women in the study community (2.6% of all 50-59 year olds) and 0.1% of the men were being treated for thyroid disease at the primary care centre, roughly 1.0% of adults subjected to screening were found to have thyroid disease requiring treatment, and most patients with a thyroid stimulating hormone concentration of 0.20 mU/l or less did not have thyroid dysfunction. It is concluded that measuring the basal serum thyroid stimulating hormone concentration by present methods is insufficient for the biochemical assessment of thyroid dysfunction in unselected populations.

Cross-Sectional Studies↗

Estrogen and thyroid-stimulating hormone (TSH) receptors in neoplastic and nonneoplastic human thyroid tissue.

Estrogen-binding receptors (ER) and thyroid-stimulating hormone (TSH) receptors were observed in the cytosol and in a membrane particulate fraction, respectively, in most neoplastic and nonneoplastic human thyroid tissues. Fourteen of 15 thyroid neoplasms and 6 of 15 nonneoplastic thyroid specimens had estrogen receptors (assuming the sensitivity of our estrogen receptor assay is 0.2 fmole/mg protein), and 14 of 15 thyroid neoplasms and 11 of 15 nonneoplastic thyroid specimens had a high affinity, low capacity TSH receptor. Neoplastic thyroid tissue had more ER (2.35 +/- 0.70/fmole/mg protein) than nonneoplastic thyroid tissue (0.57 +/- 0.181/fmole/mg protein) removed from the same patients (P less than 0.05). The Kd for ER did not differ in nonneoplastic (0.41 +/- 0.090 nM) and neoplastic (0.311 +/- 0.048 nM) thyroid tissue. The number of TSH receptors was comparable in neoplastic (0.609 +/- 0.191 pmole/mg protein) and in nonneoplastic (0.765 +/- 0.181 pmole/mg protein) thyroid tissue removed from the same patients who had the ER studies. The maximal adenylate cyclase response to TSH was greater in the neoplastic (147 +/- 26.9 pmole/mg protein/30 min) than in nonneoplastic thyroid tissue (32.8 +/- 6.69 pmole/mg protein/30 min) (P less than 0.001) suggesting a greater metabolic responsiveness of the neoplastic thyroid tissue to TSH. No correlation was evident, however, between the number of estrogen and TSH receptors in nonneoplastic and neoplastic thyroid tissue (r = 0.226). This study demonstrates that neoplastic human thyroid tissues have both estrogen receptors and TSH receptors. The neoplastic tissue also has a greater AC response to TSH than nonneoplastic thyroid tissue.

Adenocarcinoma↗

Comparison of administration of recombinant human thyrotropin with withdrawal of thyroid hormone for radioactive iodine scanning in patients with thyroid carcinoma.

BACKGROUND: To detect recurrent disease in patients who have had differentiated thyroid cancer, periodic withdrawal of thyroid hormone therapy may be required to raise serum thyrotropin concentrations to stimulate thyroid tissue so that radioiodine (iodine-131) scanning can be performed. However, withdrawal of thyroid hormone therapy causes hypothyroidism. Administration of recombinant human thyrotropin stimulates thyroid tissue without requiring the discontinuation of thyroid hormone therapy. METHODS: One hundred twenty-seven patients with thyroid cancer underwent whole-body radioiodine scanning by two techniques: first after receiving two doses of thyrotropin while thyroid hormone therapy was continued, and second after the withdrawal of thyroid hormone therapy. The scans were evaluated by reviewers unaware of the conditions of scanning. The serum thyroglobulin concentrations and the prevalence of symptoms of hypothyroidism and mood disorders were also determined. RESULTS: Sixty-two of the 127 patients had positive whole-body radioiodine scans by one or both techniques. The scans obtained after stimulation with thyrotropin were equivalent to the scans obtained after withdrawal of thyroid hormone in 41 of these patients (66 percent), superior in 3 (5 percent), and inferior in 18 (29 percent). When the 65 patients with concordant negative scans were included, the two scans were equivalent in 106 patients (83 percent). Eight patients (13 percent of those with at least one positive scan) were treated with radioiodine on the basis of superior scans done after withdrawal of thyroid hormone. Serum thyroglobulin concentrations increased in 15 of 35 tested patients: 14 after withdrawal of thyroid hormone and 13 after administration of thyrotropin. Patients had more symptoms of hypothyroidism (P<0.001) and dysphoric mood states (P<0.001) after withdrawal of thyroid hormone than after administration of thyrotropin. CONCLUSIONS: Thyrotropin stimulates radioiodine uptake for scanning in patients with thyroid cancer, but the sensitivity of scanning after the administration of thyrotropin is less than that after the withdrawal of thyroid hormone. Thyrotropin scanning is associated with fewer symptoms and dysphoric mood states.

Adult↗

Relation between phenotype and intra-cellular thyroid hormone effect in patients with altered peripheral thyroid hormone sensitivity.

OBJECTIVE: We wished to ascertain whether different phenotypic appearances in patients with altered cellular sensitivity to thyroid hormones were related to the type of altered intra-cellular thyroid hormone effect. DESIGN: Blood samples were obtained from two members of a family suffering from generalized thyroid hormone resistance (GTHR) for hormone assays and examination of the cellular thyroid hormone effect, and the results compared with results from other families with signs of altered peripheral thyroid hormone sensitivity. PATIENTS: Two members of a family with thyroid hormone resistance and nine normal persons were studied. MEASUREMENTS: Basal thyroid hormone function tests were measured. The thyroid hormone effect on mononuclear blood cells was determined by measuring the thyroid hormone stimulated oxygen consumption and glucose uptake. RESULTS: The two family members appeared phenotypically normal except for nodular goitre. Thyroid hormone stimulated glucose uptake was depressed whereas thyroid hormone stimulated oxygen consumption was normal. CONCLUSION: Comparison of the present results of the cellular examination in two patients with GTHR, with the results obtained in other families with altered peripheral thyroid hormone sensitivity, suggest that the classic GTHR (phenotype: normal or with goitre) is linked to impaired thyroid hormone stimulated glucose uptake, whereas in patients with osteopetrosis, the thyroid hormone insensitivity seems located at the mitochondrial level (impaired thyroid hormone stimulated oxygen consumption.

Adult↗

The effect of treatment with levothyroxine or iodine on thyroid size and thyroid growth stimulating immunoglobulins in endemic goitre patients.

OBJECTIVE: We assessed the effect of levothyroxine or iodine on thyroid size and on thyroid growth stimulating immunoglobulins in endemic goitre patients. DESIGN: Levothyroxine or iodine was given orally in an open randomized prospective study (100 and 200 micrograms respectively). PATIENTS: Thirty-seven euthyroid patients with diffuse iodine deficiency goitres and thyroid growth stimulating immunoglobulins were studied. MEASUREMENTS: Thyroid size, thyroid growth stimulating immunoglobulins (mitosis arrest assay), basal TSH, free T3, free T4, thyroid anti-microsomal antibodies, antithyroglobulin antibodies, anti-TSH receptor antibodies and urinary iodine excretion were measured. RESULTS: Thyroid size decreased significantly in both groups, in the levothyroxine group more than in the iodine treated group. Thyroid growth stimulating immunoglobulins levels also decreased significantly in both groups. Between groups there was no statistically significant difference. A statistically significant correlation between thyroid growth stimulating immunoglobulins reduction profiles and goitre size reduction could not be established. TSH levels became suppressed in the levothyroxine group while the T4 values rose; in the iodine treated group TSH levels stayed constant as did T4. None of the patients developed thyroid microsomal or thyroglobulin auto-antibodies and/or hyperthyroidism during the treatment. CONCLUSIONS: Levothyroxine as well as iodine was effective in reducing thyroid size as well as thyroid growth stimulating immunoglobulins levels in endemic goitre patients. Since in both groups TSH levels were not related to thyroid size reduction, other factors than TSH suppression must be responsible for the observed thyroid size reduction. Iodine itself by virtue of its antiproliferative action on thyrocytes may have had a direct action on the goitre reduction during iodine treatment; however, the levothyroxine dose, containing less iodine, had a similar effect. A complicated picture hence emerges with regard to factors involved in the shrinkage of iodine deficiency goitre during thyroxine or iodine therapy. These findings indicate that TSH and thyroid growth promoting immunoglobulins are not the only influences on the size of endemic goitres, although it cannot be excluded that these two factors contribute to influence the pathogenetic process.

Antibodies↗

Antibodies producing complement-mediated thyroid cytotoxicity in patients with atrophic or goitrous autoimmune thyroiditis.

Thyroid-cytotoxic antibodies (thyroid-cytotoxic Abs) have been described in patients with autoimmune thyroiditis, but their role in the development of hypothyroidism remains to be clarified. In this study, we evaluated the pathogenetic role of thyroid-cytotoxic Abs in 20 patients with atrophic thyroiditis (idiopathic myxedema; AT) and 94 patients with goitrous Hashimoto's thyroiditis (HT). Among patients with HT, 27 were euthyroid (HT-E), 27 had subclinical hypothyroidism (HT-SH), and 40 had overt hypothyroidism (HT-H). Seventeen normal subjects and 8 patients with nonthyroidal illnesses were used as controls (C). To detect thyroid-cytotoxic Abs, human thyroid cells expressing thyroid peroxidase (TPO) were labeled with 51Cr and challenged with the immunoglobulin G (IgG) fraction of serum plus rabbit complement. The cytotoxic effect of IgGs was calculated as the percent specific lysis (% SL), taking into account the lytic effect of complement alone and the maximal lysis produced by a detergent. Most C-IgGs decreased the cytotoxic effect of complement (median % SL, -3.3). IgGs from hypothyroid patients with thyroiditis had a greater cytotoxic effect than C-IgGs, either as a whole group (P < 0.001), or when subdivided according to clinical diagnosis: HT-SH (median % SL, 4.8; P < 0.005), HT-H (%SL, 2.2; P < 0.0001), or AT (%SL, 0.9; P < 0.01). Among patients with HT, the lytic activity of IgGs from patients with subclinical and overt hypothyroidism was higher than that of IgGs from euthyroid patients (P < 0.05). The results of IgGs from euthyroid patients with HT (median % SL, -0.9) did not significantly differ from those of C-IgGs. By taking a cut-off over the upper range of % SL produced by C-IgGs (> 2), the prevalence of thyroid-cytotoxic Abs was 30% in AT, 59% in HT-SH, and 55% in HT-H. However, 37% of euthyroid patients with HT also had thyroid-cytotoxic Abs. No IgG containing TPO antibodies (TPOAb) at low titer (< 40(2)) was cytotoxic. However, the levels of thyroid-cytotoxic Abs did not correlate with TPOAb titers, and preabsorption with TPO only partially abolished the lytic effect of some HT-IgG. These findings suggest that TPO is a target of thyroid-cytotoxic Abs, but other thyroid antigens are also involved in the cytotoxic reaction.(ABSTRACT TRUNCATED AT 400 WORDS)

Adolescent↗

Thyroid vascularity and blood flow are not dependent on serum thyroid hormone levels: studies in vivo by color flow doppler sonography.

OBJECTIVE: Thyroid blood flow is greatly enhanced in untreated Graves' disease, but it is not known whether it is due to thyroid hormone excess or to thyroid hyperstimulation by TSH-receptor antibody. To address this issue in vivo patients with different thyroid disorders were submitted to color flow doppler sonography (CFDS). SUBJECTS AND METHODS: We investigated 24 normal subjects, and 78 patients with untreated hyperthyroidism (49 with Graves' hyperthyroidism, 24 with toxic adenoma, and 5 patients with TSH-secreting pituitary adenoma (TSHoma)), 19 patients with thyrotoxicosis (7 with thyrotoxicosis factitia, and 12 with subacute thyroiditis), 37 euthyroid patients with goitrous Hashimoto's thyroiditis, and 21 untreated hypothyroid patients with Hashimoto's thyroiditis. RESULTS: Normal subjects had CFDS pattern 0 (absent or minimal intraparenchimal spots) and mean intraparenchimal peak systolic velocity (PSV) of 4.8+/-1.2cm/s. Patients with spontaneous hyperthyroidism due to Graves' disease, TSHoma, and toxic adenoma had significantly increased PSV (P<0.0001, P=0.0004, P<0.0001 respectively vs controls) and CFDS pattern. Patients with Graves' disease had CFDS pattern II (mild increase of color flow doppler signal) in 10 (20%) and pattern III (marked increase) in 39 cases (80%). Mean PSV was 15+/-3cm/s. Patients with toxic adenoma had CFDS pattern I (presence of parenchymal blood flow with patchy uneven distribution) in 2 (8%), pattern II in 16 (70%) and pattern III in 5 (22%). Mean PSV was 11+/-2.4cm/s. Patients with TSHoma showed CFDS pattern I in one case (20%) and pattern II in 4 (80%). Mean PSV was 14.8+/-4.2cm/s. Patients with thyrotoxicosis had normal PSV (4.2+/-1. 1cm/s in subacute thyroiditis, 4+/-0.8cm/s in thyrotoxicosis factitia, P=not significant vs controls) and CFDS pattern 0. Untreated euthyroid patients with goitrous Hashimoto's thyroiditis had CFDS pattern 0, and mean PSV (4.3+/-0.9cm/s; P=not significant vs controls). Untreated hypothyroid patients with goitrous Hashimoto's thyroiditis had CFDS pattern I in 14 cases (67%), pattern II in 4 (19%) and pattern 0 in 3 (14%) and mean PSV (5.6+/-1. 4cm/s) was higher than that of controls (P=0.026). CONCLUSIONS: An increase in both intrathyroidal vascularity and blood velocity was observed in patients with spontaneous hyperthyroidism but not in thyrotoxicosis due to either ingestion of thyroid hormones or to a thyroidal destructive process. The slightly increased vascularity and blood velocity observed in patients with hypothyroid Hashimoto's thyroiditis suggests that thyroid stimulation by either TSH-receptor antibody or TSH is responsible for the increased thyroid blood flow.

Adolescent↗

Radiation dose-response relationships for thyroid nodules and autoimmune thyroid diseases in Hiroshima and Nagasaki atomic bomb survivors 55-58 years after radiation exposure.

CONTEXT: Effects of irradiation on thyroid diseases such as thyroid nodules and autoimmune thyroid diseases have not been evaluated among people exposed to radiation more than 50 years in the past. OBJECTIVE: To evaluate the prevalence of thyroid diseases and their radiation-dose responses in atomic bomb survivors. DESIGN, SETTING, AND PARTICIPANTS: Survey study comprising 4091 cohort members (mean age, 70 [SD, 9] years; 1352 men and 2739 women) who participated in the thyroid study at the Radiation Effects Research Foundation. Thyroid examinations were conducted between March 2000 and February 2003. MAIN OUTCOME MEASURES: Prevalence of thyroid diseases, including thyroid nodules (malignant and benign) and autoimmune thyroid diseases, and the dose-response relationship of atomic bomb radiation in each thyroid disease. RESULTS: Thyroid diseases were identified in 1833 (44.8%) of the total participants (436 men [32.2% of men] and 1397 women [51.0% of women]) (P<.001). In 3185 participants, excluding persons exposed in utero, not in the city at the time of the atomic bombings, or with unknown radiation dose, the prevalence of all solid nodules, malignant tumors, benign nodules, and cysts was 14.6%, 2.2%, 4.9%, and 7.7%, respectively. The prevalence of positive thyroid antibodies, antithyroid antibody-positive hypothyroidism, and Graves disease was 28.2%, 3.2%, and 1.2%, respectively. A significant linear dose-response relationship was observed for the prevalence of all solid nodules, malignant tumors, benign nodules, and cysts (P<.001). We estimate that about 28% of all solid nodules, 37% of malignant tumors, 31% of benign nodules, and 25% of cysts are associated with radiation exposure at a mean and median thyroid radiation dose of 0.449 Sv and 0.087 Sv, respectively. No significant dose-response relationship was observed for positive antithyroid antibodies (P = .20), antithyroid antibody-positive hypothyroidism (P = .92), or Graves disease (P = .10). CONCLUSIONS: A significant linear radiation dose response for thyroid nodules, including malignant tumors and benign nodules, exists in atomic bomb survivors. However, there is no significant dose response for autoimmune thyroid diseases.

Aged↗

Thyroid blood flow evaluation by color-flow Doppler sonography distinguishes Graves' disease from Hashimoto's thyroiditis.

Thyroid hypoechogenicity at ultrasound is a characteristic of autoimmune thyroid diseases, with an overlap of this echographic pattern in patients affected by Graves' disease or Hashimoto's thyroiditis. Aim of the present paper was to study the thyroid blood flow (TBF) by color-flow doppler (CFD) and peak systolic velocity (PSV) at the inferior thyroid artery in 37 Graves' and 45 goitrous Hashimoto's thyroiditis patients. CFD pattern was defined as normal (or type 0): TBF limited to peripheral thyroid arteries (PSV = 17.7 +/- 3 cm/sec, mean +/- SD); type I: TBF mildly increased; type II: TBF clearly increased; type III: TBF markedly increased. The CFD was in direct relationship to the PSV. Out of 18 patients with Graves' disease and untreated active hyperthyroidism CFD pattern was type III in 17 and type II in 1. The PSV was 42.1 +/- 15 cm/sec. In 17 patients euthyroid under methimazole, the CFD pattern was type 0 in 3 (17%) type I in 5 (30%), type II in 5 (30%), type III in 4 (23%). In this group of Graves' patients the PSV was 36 +/- 14 cm/sec. In two patients, hypothyroid after radioiodine treatment, the CFD pattern was type 0 in 1 and type I in 1. In the group of Hashimoto's patients TBF was in no relationship with thyroid status or treatment and was type 0 in 22 (49%), type I in 20 (44%), type II in 3 (7%), while none had type III CFD pattern. Thyroid hypoechogenicity at ultrasound was present in 32/37 (86%) Graves' and 41/45 (91%) Hashimoto's patients. All the four patients with Hashimoto's thyroiditis and normal thyroid ultrasound pattern had also a normal CFD pattern, while 4/5 patients with Graves' disease and normal echographic pattern had an increased TBF. In conclusion, a diffusely increased thyroid blood flow is pathognomonic of untreated Graves' disease and an abnormal CFD pattern identifies the majority of Graves' patients with a normal thyroid ultrasound pattern. Thus, CFD sonography may be useful in distinguishing patients with Graves' disease and Hashimoto's thyroiditis having a similar thyroid echographic pattern at ultrasound.

Diagnosis, Differential↗

Thyroid cancer and thyroiditis in the goitrous region of Salta, Argentina, before and after iodine prophylaxis.

OBJECTIVE: The importance of iodine intake and thyroiditis in the pathogenesis of thyroid cancer remains controversial. We have investigated the natural history of thyroid cancer and thyroiditis in a goitrous region before and after iodine prophylaxis over a 31-year period. DESIGN: For the analysis of thyroid cancer the material was divided in two periods. The first 15 years (59 cases), including 5 years before prophylaxis, was compared with the second 16 years (85 cases), a period well after iodine supplementation of salt. Histological diagnosis of the tumours was based on the WHO system. Moderate to severe thyroiditis in the non-tumoral surrounding thyroid from female patients was recorded. For this, the material was analysed in the two periods in relation to the introduction of iodine prophylaxis in 1963, taking account of the age of the patients. RESULTS: Papillary carcinomas formed the largest group of tumours in both periods, with nearly twice as many in the second period as the first, while the numbers of follicular and medullary carcinomas remained about the same. The ratio of papillary to follicular carcinoma rose from 1.7:1 in the first period to 3.1:1 in the second. All three thyroid lymphomas were of the non-Hodgkin's type, and all occurred in the second period in females aged over 50. A severe lymphoid thyroiditis was present in the two cases with assessable background thyroid tissue. The frequency of lymphoid infiltrate in females rose from 8% (1/12) before 1963 to 25% (18/72) after prophylaxis in the whole series. After salt prophylaxis, thyroiditis was more frequent in patients with papillary carcinoma in general (31%), and clinically significant papillary carcinomas in particular (35%), than in those with non-papillary tumours (6%) (chi 2, P < 0.05 and P < 0.025, respectively). CONCLUSIONS: Our observations indicate that a high dietary intake of iodine may be associated with a high frequency of papillary carcinoma and thyroiditis, and that thyroiditis is more commonly associated with papillary carcinoma than with other thyroid tumours. The occurrence of non-Hodgkin's lymphomas only in the post-prophylaxis period may be linked to an increase in thyroiditis.

Adolescent↗