ENDOCRINE TUMOURS: Thyrotropin-secreting pituitary adenoma: a structured review of 535 adult cases

BACKGROUND AND AIMS

Thyrotropin-secreting pituitary adenomas (TSHomas) are a rare entity, occurring in one per million people. We performed a systematic review of 535 adult cases summarizing the clinical, biochemical, hormonal and radiological characteristics of TSHoma. Furthermore, we discussed the current guidelines for diagnosis and treatment.

METHODS

A structured research was conducted using Pubmed and Web of Science with the following MeSH terms: 'thyrotropin secreting pituitary adenoma' OR 'TSHoma' OR 'thyrotropinoma.'

RESULTS

Our analysis included 535 cases originating from 18 case series, 5 cohort studies and 91 case reports. The mean age at diagnosis was 46 years. At presentation, 75% had symptoms of hyperthyroidism, 55.5% presented with a goitre and 24.9% had visual field defects. The median TSH at diagnosis was 5.16 (3.20-7.43) mU/L with a mean FT4 of 41.5 ± 15.3 pmol/L. The majority (76.9%) of the TSHomas were macroadenoma. Plurihormonality was seen in 37.4% of the adenoma with a higher incidence in macroadenoma. Surgical resection of the adenoma was performed in 87.7% of patients of which 33.5% had residual pituitary adenoma. Post-operative treatment with a somatostatin analogue (SSA) led to a stable disease in 81.3% of the cases with residual tumour. We noticed a significant correlation between the diameter of the adenoma and residual pituitary adenoma (r = 0.490, P < 0.001). However, in patients preoperatively treated with an SSA, this correlation was absent.

CONCLUSION

TSHomas are a rare cause of hyperthyroidism and are frequently misdiagnosed. Based on our structured analysis of case series, cohort studies and case reports, we conclude that the majority of TSHomas are macroadenoma being diagnosed in the fifth to sixth decade of life and presenting with symptoms of hyperthyroidism. Plurihormonalitiy is observed in one-third of TSHomas. Treatment consists of neurosurgical resection and SSA in case of surgical failure.

MicroRNAs in thyroid development, function and tumorigenesis

MicroRNAs (miRNAs) are important post-transcriptional regulators of gene expression that modulate the vast majority of cellular processes. During development, the correct timing and expression of miRNAs in the tissue differentiation is essential for organogenesis and functionality. In thyroid gland, DICER and miRNAs are necessary for accurately establishing thyroid follicles and hormone synthesis. Moreover, DICER1 mutations and miRNA deregulation observed in human goiter influence thyroid tumorigenesis. The thyroid malignant transformation by MAPK oncogenes is accompanied by global miRNA changes, with a marked reduction of "tumor-suppressor" miRNAs and activation of oncogenic miRNAs. Loss of thyroid cell differentiation/function, and consequently iodine trapping impairment, is an important clinical characteristic of radioiodine-refractory thyroid cancer. However, few studies have addressed the direct role of miRNAs in thyroid gland physiology. Here, we focus on what we have learned in the thyroid follicular cell differentiation and function as revealed by cell and animal models and miRNA modulation in thyroid tumorigenesis.

Hypothyroidism associated with parathyroid disorders

Hypothyroidism may occur in association with congenital parathyroid disorders determining parathyroid hormone insufficiency, which is characterized by hypocalcemia and concomitant inappropriately low secretion of parathormone (PTH). The association is often due to loss of function of genes common to thyroid and parathyroid glands embryonic development. Hypothyroidism associated with hypoparathyroidism is generally mild and not associated with goiter; moreover, it is usually part of a multisystemic involvement not restricted to endocrine function as occurs in patients with 22q11 microdeletion/DiGeorge syndrome, the most frequent disorders. Hypothyroidism and hypoparathyroidism may also follow endocrine glands' damages due to autoimmunity or chronic iron overload in thalassemic disorders, both genetically determined conditions. Finally, besides PTH deficiency, hypocalcemia can be due to PTH resistance in pseudohypoparathyroidism; when hormone resistance is generalized, patients can suffer from hypothyroidism due to TSH resistance. In evaluating patients with hypothyroidism and hypocalcemia, physical examination and clinical history are essential to drive the diagnostic process, while routine genetic screening is not recommended.

Respiratory Manifestations of Hypothyroidism: A Systematic Review

BACKGROUND

Hypothyroidism has been associated with increased pulmonary morbidity and overall mortality. A systematic review was conducted to identify the prevalence and underlying mechanisms of respiratory problems among patients with thyroid insufficiency.

METHODS

PubMed and EMBASE databases were searched for relevant literature from January 1950 through January 2015 with the following study eligibility criteria: English-language publications; adult subclinical or overt hypothyroid patients; intervention, observational, or retrospective studies; and respiratory manifestations. The Preferred Reporting Items for Systematic reviews and Meta-Analyses statement was followed, and Cochrane's risk of bias tool was used.

RESULTS

A total of 1699 papers were screened by two independent authors for relevant titles. Of 109 relevant abstracts, 28 papers underwent full-text analyses, of which 22 were included in the review. Possible mechanisms explaining respiratory problems at multiple physiological levels were identified, such as the ventilator control system, diaphragmatic muscle function, pulmonary gas exchange, goiter caused upper airway obstruction, decreased capacity for energy transduction, and reduced glycolytic activity. Obstructive sleep apnea syndrome was found among 30% of newly diagnosed patients with overt hypothyroidism, and demonstrated reversibility following treatment. The evidence for or against a direct effect on pulmonary function was ambiguous. However, each of the above-mentioned areas was only dealt with in a limited number of studies. Therefore, it is not possible to draw any strong conclusions on any of these themes. Moreover, most studies were hampered by considerable risk of bias due for example to small numbers of patients, lack of control groups, randomization and blinding, and differences in body mass index, sex, and age between subjects and controls.

CONCLUSION

Mechanistic data linking hypothyroidism and respiratory function are at best limited. This area of research is therefore open for retesting hypotheses, using appropriate study designs and methods.

[The mother-placenta-fetus system in diffuse toxic goiter: Morphopathological aspects]

OBJECTIVE

to compare the clinical and morphological parallels of the mother-placenta-fetus system in diffuse toxic goiter (DTG) through current morphological examinations.

SUBJECTS AND METHODS

Sixty-five women whose pregnancy occurred with DTG were examined using both clinical and morphological studies (light, scanning electron, and atomic-force microscopies and macro- and microelement analysis); the placenta and uterus were investigated.

RESULTS

Destructive changes and microrelief impairment, resulting from circulatory disorders (ischemia) and hemic hypoxia, were observed in the presence of DTG during pregnancy. Abnormal placental immaturity developed; the number of terminal villi decreased; sclerosis occurred. The magnitude of changes showed up to a greater extent in the myometrium, umbilical cord, and placenta of women, whose pregnancy occurred with DTG, and in patients with disease recurrence. In preeclampsia, plethora, stasis, and thrombosis were added to circulatory disorders.

CONCLUSION

Not only the diagnosis itself of DTG, but also the type of its course and the pattern of obstetric disease, primarily preeclampsia, affect the state of structural components of the uteroplacental unit.

The impact of goitre and its treatment on the trachea, airflow, oesophagus and swallowing function. A systematic review

In this systematic review, we investigated the effects of goitre and its treatment on the trachea and the oesophagus. A total of 6355 papers were screened in scientific databases, which disclosed 40 original studies (nine descriptive and 31 interventional). Although most studies are hampered by a number of methodological shortcomings, it is uncontested that goitre affects the trachea as well as the oesophagus in a large proportion of people. This leads to upper airway obstruction, swallowing dysfunction, or both, which may remain undisclosed unless specifically investigated for. Assessment of the tracheal dimensions should be done by magnetic resonance imaging or computed tomography, and detection of upper airway obstruction by flow volume loops, with focus on the inspiratory component. A clinical evaluation of the oesophageal function is difficult to implement and could be replaced by available and validated questionnaires on swallowing. Although radioiodine therapy and thyroidectomy relieve the negative effect of goitre on the trachea and the oesophagus, many issues remain unexplored.

[The use of phytotherapy for treatment of thyroid diseases]

The main tasks during treatment of hyperplastic thyroid diseases--to stop the growth of thyroid nodules; compensation of hypothyrosis; normalization of thyroid size. One of the perspective methods in combine therapy of diffuse and mix goiter is a phytotherapy. The most often for thyroid diseases we have used the plant drug Polentilla alba, which on Ukrainian market was registered as "Alba". Investigation has shown, that phytodrug of Polentilla alba could be recommended for monotherapy and for combine conservative therapy of diffuse and mix benign euthyroid goiter, and also for complex treatment of toxic and hypothyroid goiters.

Absence of primary hypothyroidism and goiter in Slc26a4 (-/-) mice fed on a low iodine diet

BACKGROUND

Mutations in the SLC26A4 gene, coding for the anion transporter pendrin, are responsible for Pendred syndrome, characterized by congenital sensorineural deafness and dyshormonogenic goiter. The physiological role of pendrin in the thyroid is still unclear and the lack of a thyroid phenotype in some patients with SLC26A4 mutations and in Slc26a4 (-/-) mice indicate the existence of environmental or individual modifiers able to compensate for pendrin inactivation in the thyroid. Since pendrin can transport iodide in vitro, variations in iodide supply have been claimed to account for the thyroid phenotype associated with pendrin defects.

AIM

The Slc26a4 (-/-) mouse model was used to test the hypothesis that iodide supply may influence the penetrance and expressivity of SLC26A4 mutations.

MATERIALS AND METHODS

Slc26a4 (-/-) and (+/+) mice were fed up to 6 months on a standard or low iodine diet and were evaluated for thyroid structural abnormalities or biochemical hypothyroidism.

RESULTS

A 27-fold iodide restriction induced similar modifications in thyroid histology, but no differences in thyroid size, T4 or TSH levels were observed between between Slc26a4 (-/-) and (+/+) mice, either in standard conditions and during iodine restriction.

CONCLUSIONS

Iodide restriction is not able to induce a thyroid phenotype in Slc26a4 (-/-) mice. These experimental data, together with those coming from a review of familial Pendred cases leaving in regions either with low or sufficient iodide supply, support the idea that the expression of thyroid phenotype in Pendred syndrome is more powerfully influenced by individual factors than by dietary iodide.

[Selective pituitary resistance to thyroid hormone in a patient treated with amiodarone]

Selective pituitary resistance to thyroid hormones is a syndrome that involves inadequate response of thyroid-stimulating hormone to changes in thyroid hormones. Unlike generalized resistance syndromes, this entity produces central hyperthyroidism and clinical thyrotoxicosis. Sometimes the disease may not be properly diagnosed and is treated with drugs with harmful effects on the thyroid, such as amiodarone, hampering diagnosis and possibly exacerbating the disorder. The treatment of this condition can be symptomatic, based on control of tachycardia and anxiety, or etiological, acting on the pituitary to regulate thyrotropin secretion or on the thyroid gland to control thyroid hormone production. We report the case of a patient with pituitary resistance to thyroid hormone, who was treated with amiodarone to control paroxysmal atrial fibrillation.

Use of ultrasound to distinguish between fetal hyperthyroidism and hypothyroidism on discovery of a goiter

OBJECTIVES

To determine whether sonography can be used to distinguish hyperthyroidism from hypothyroidism in pregnancies with fetal goiter.

METHODS

This was a retrospective study of 39 cases of fetal goiter. The majority of the mothers had Graves' disease. Fetuses were scanned for the existence of a hypertrophic thyroid gland (goiter) beginning at 22 gestational weeks. Once a goiter was diagnosed, different echographic features were analyzed and the effect of chosen treatment on fetal thyroid development was monitored.

RESULTS

On color Doppler, 68.8% of hypothyroid goiters had a peripheral vascular pattern vs. 20% in cases of fetal hyperthyroidism (P = 0.0574). No hypothyroid goiter presented central vascularization whereas half the hyperthyroid goiters did (P = 0.0013). Fetal tachycardia was a good indicator of hyperthyroidism (57.1% v.s 6.3%; P = 0.0055). Delayed bone maturation was seen in hypothyroid goiters (46.9% vs. 0%; P = 0.0307), while advanced bone maturity was specific to hyperthyroid goiters (85.7% vs. 0%; P < 0.0001). Lastly, an increase in fetal movement was observed in cases of fetal hypothyroidism (43.8% vs. 0%; P = 0.0364).

CONCLUSION

Based on the color Doppler pattern of goiter, fetal heart rate, bone maturation and fetal mobility, we established an ultrasound score to predict fetal thyroid function in cases of fetal goiter.

Goitre and hearing impairment in a patient with Pendred syndrome

A case is described here of a young euthyroid woman with a goitre and hearing impairment. Perchlorate discharge test showed increased washout of iodine. Genetic analysis confirmed the diagnosis of Pendred syndrome as a mutation in the Pds gene was found. The patient was treated with potassium iodine orally. During follow-up there where no symptoms of hyperthyroidism and the size of the goitre decreased.

Which domains of thyroid-related quality of life are most relevant? Patients and clinicians provide complementary perspectives

OBJECTIVE

To identify how thyroid diseases impact the patients' lives and to select the most relevant quality of life (QoL) issues for a thyroid-specific questionnaire.

DESIGN

Fifteen thyroid experts and 80 thyroid outpatients (14 with nontoxic goiter, 12 nodular toxic goiter, 21 Graves' disease, 17 thyroid-associated ophthalmopathy, and 16 primary hypothyroidism) were interviewed.

METHODS

The relevance of 138 thyroid disease-related issues was rated during interviews. For each issue, three relevance measures were obtained: a diagnosis-specific patient rating, a diagnosis-specific expert rating, and a combined overall patient/expert rating. The 75 most relevant issues overall and the 15 most relevant issues in each patient category were selected.

RESULTS

Based on the above, 92 issues were selected, covering a broad range of clinical and QoL domains. Across patient groups, broader QoL domains were most relevant, especially fatigue and emotional susceptibility. However, when focusing on individual patient groups, diagnosis-related physical symptoms were very relevant too. Patients rated issues about psychosocial problems and impact on daily life as more relevant, whereas clinicians focused on thyroid-characteristic issues.

CONCLUSIONS

A broad range of QoL issues and physical symptoms are relevant for thyroid patients, particularly fatigue and emotional susceptibility. Patients and clinicians offer complementary perspectives on relevance.

[Clinical effect of Prunellae Oral Liquid on goiter with different thyroid function]

OBJECTIVE

To observe the clinical effects of Prunellae Oral Liquid (POL) on the size of thyroid with different states of thyroid function in patients of goiter.

METHODS

Fifty-six patients with hyperthyroidism, 24 with hypothyroidism and 18 with simple goiter were randomized into two groups. Group A treated by classical therapy, Group B by POL based on classical therapy. Size of thyroid of patients before and after treatment was measured by color ultrasonic Doppler and compared with the data obtained from 20 healthy subjects as control.

RESULTS

Size of thyroid in all patients before treatment were obviously larger than that of normal control (P<0.01), but it reduced after treatment in both groups, especially in group B, in which it differed insignificantly to that in the normal control (P > 0.05).

CONCLUSION

Combined treatment of Chinese medicine (using POL) and Western medicine is superior to Western medicine alone in treating goiter with different states of thyroid function.

Investigation of intelligence quotient and psychomotor development in schoolchildren in areas with different degrees of iodine deficiency

This investigation aims to observe the intelligence and psychomotor development of the schoolchildren in iodine deficiency (ID) areas after the adoption of Universal Salt Iodization (USI), and evaluate the effect of the adoption of USI on their intelligence and psychomotor development. 564 schoolchildren (306 males and 258 females, age range from 8 to 13 yrs) from areas with severe, moderate, and mild ID were investigated. Intelligence quotient (IQ) was measured by Combined Raven's test, second edition. Psychomotor development was examined by Jinyi Psychomotor Test Battery (JPB). We found that the IQ scores of all subjects in the severe and moderate ID areas were 102 +/- 15.6 and 99.5 +/-16.6 respectively, lower than those in the mild ID areas (108 +/- 12.4, p < 0.01). The IQ scores correlated negatively with age (partial r = -0.17; beta = -1.95; p < 0.0001). The total T scores of JPB of all subjects in the severe and moderate ID areas were 316 +/- 42.3 and 330 +/- 47.7 respectively, lower than those in the mild ID areas (342 +/- 48.1, p < 0.05). The total T scores of JPB correlated negatively with age (partial r = -0.15; beta = -4.94; p = 0.0006). We may conclude that after the adoption of USI in the ID areas investigated, USI has probably made a contribution to the partial recovery of intelligence and psychomotor development injured by ID in schoolchildren, and should be strengthened.

[Epidemiological study of the effects of smoking cigarette on thyroid gland]

OBJECTIVE

To investigate the effect of cigarette smoking on thyroid gland volume, thyroid function and thyroid autoantibodies in the areas with different iodine intakes.

METHODS

A cross-sectional epidemiological study in Panshan (mild iodine-deficient area), Zhangwu (more than adequate iodine intake area) and Huanghua (iodine-excessive area) was conducted in 3761 subjects in 1999.80.2 % of them were followed up in 2004. Questionnaires, thyroid function, thyroid autoantibodies, urinary iodine concentration,and thyroid B ultrasound were performed.

RESULTS

The prevalence of goiter was higher in smokers than in non-smokers (15.1% vs. 11.5%, P< 0.05). The average thyroid volume was higher in smokers with phenomenon more obvious in Panshan and Huanghua areas. Data from logistic analysis showed that smoking cigarette was an independent risk factor of goiter. There was no difference in serum TSH and Tg level between smokers and non-smokers. The positive rate of TPOAb (>100 IU/ml) was higher in smokers than in non-smokers(10.8% vs. 9.0 % , P <0.05) and was especially obvious in Huanghua area. Smoking was a independent risk factor of increasing positive rate of TPOAb. During the prospective observation,it was found that the incidence of positive TPOAb(>,100 IU/ml) was 7.4% in the subjects that were from non-smokers turning to smokers and 2.9% in those whose smoking behavior did not change. Logistic analysis indicated that the shifting from non-smoking to smoking was independent risk factor for the increase on high incidence of positive TPOAb.

CONCLUSION

Smoking cigarette was a independent risk factor of goiter. Smoking was also a risk factor of increasing TPOAb positive rate. Shifting from not smoking to smoking was an independent risk factor of increasing high incidence of positive TPOAb.

Direct calorimetry of free-moving eels with manipulated thyroid status

In birds and mammals, the thyroid gland secretes the iodothyronine hormones of which tetraiodothyronine (T4) is less active than triiodothyronine (T3). The action of T3 and T4 is calorigenic and is involved in the control of metabolic rate. Across all vertebrates, thyroid hormones also play a major role in differentiation, development and growth. Although the fish thyroidal system has been researched extensively, its role in thermogenesis is unclear. In this study, we measured overall heat production to an accuracy of 0.1 mW by direct calorimetry in a free-moving European eel (Anguilla anguilla L.) with different thyroid status. Hyperthyroidism was induced by injection of T3 and T4, and hypothyroidism was induced with phenylthiourea. The results show for the first time at the organismal level, using direct calorimetry, that neither overall heat production nor overall oxygen consumption in eels is affected by hyperthyroidism. Therefore, we conclude that the thermogenic metabolism-stimulating effect of thyroid hormones (TH) is not present with a cold-blooded fish species like the European eel. This supports the concept that TH does not stimulate thermogenesis in poikilothermic species.

Difficult intubation in thyroid surgery: myth or reality?

Thyroid surgery is considered to be a risk factor for difficult airway management. We prospectively studied 324 consecutive patients undergoing thyroid surgery to investigate the incidence of difficult intubation as evaluated by the intubation difficulty scale as well as other specific predictive factors. The overall incidence of difficult intubation was 11.1% (95% CI: 7.6-14.5). Median intubation difficulty scale was 0 (25th-75th percentile: 0; 2.7). In three predefined groups (no echographic goiter, clinically palpable goiter, and impalpable goiter), difficult intubation occurred in 10% (95% CI: 4.8-17.4), 13% (95% CI: 6.5-18.4), and 11% (95% CI: 4.7-16.8) of patients, respectively, with no statistical difference among the groups. Specific predictive criteria (palpable goiter, endothoracic goiter, airway deformation, airway compression, or thyroid malignancy) were not associated with an increased rate of difficult intubation. Classical predictive criteria (mouth opening <35 mm, Mallampati III or IV, short neck, neck mobility <80 degrees , thyromental distance <65 mm, and a retrognathic mandible) were significantly reliable in the univariate analysis as risk factors for difficult intubation.

Thyroxine in goiter, Helicobacter pylori infection, and chronic gastritis

BACKGROUND

Malabsorption of thyroxine has been described in patients treated with drugs that modify an acidic environment. We determined whether there is an increased need for thyroxine in patients with euthyroid multinodular goiter and impaired secretion of gastric acid.

METHODS

We assessed the dose of thyroxine required to obtain a low level of thyrotropin (0.05 to 0.20 mU per liter) in 248 patients with multinodular goiter. Of these 248 patients, 53 also had Helicobacter pylori-related gastritis and 60 had atrophic gastritis of the body of the stomach (31 with evidence of H. pylori infection and 29 without such evidence). The reference group comprised 135 patients with multinodular goiter and no gastric disorders. In addition, variation in the level of serum thyrotropin was prospectively studied in 11 patients treated with thyroxine before and after H. pylori infection and both before and during treatment with omeprazole in 10 patients treated with thyroxine who had gastroesophageal reflux.

RESULTS

The daily requirement of thyroxine was higher (by 22 to 34 percent) in patients with H. pylori-related gastritis, atrophic gastritis, or both conditions than in the reference group. In prospective studies, the occurrence of H. pylori infection in the 11 patients treated with thyroxine led to an increase in the level of serum thyrotropin (P=0.002), an effect that was nearly reversed on eradication of H. pylori infection. In a similar way, omeprazole treatment was associated with an increase in the level of serum thyrotropin in all 10 patients treated with thyroxine, an effect that was reversed by an increase in the thyroxine dose by 37 percent.

CONCLUSIONS

Patients with impaired acid secretion require an increased dose of thyroxine, suggesting that normal gastric acid secretion is necessary for effective absorption of oral thyroxine.

Goitre and iodine deficiency in Afghanistan: a case-control study

I deficiency is the leading cause of preventable mental retardation. A number of surveys in Afghanistan show goitre prevalence rates more than 20 % amongst children and women. Access to iodised salt remains low, with disparate coverage by region, despite the recent implementation of a national salt iodisation programme. The objectives were to identify whether the presence of goitre is a satisfactory marker of I deficiency and to examine the relationship between goitre and thyroid function. A case-control study was carried out in children and women of childbearing age, stratified on the presence of goitre. Adequate levels of urinary I were observed in 6.8 % of all the subjects, and amongst the subjects without goitre, this figure was only 9 %. The presence of goitre was significantly associated with severe urinary I deficiency; however, the difference between the cases and controls was not as great as expected. An association between the presence of goitre and elevated thyroid-stimulating hormone (TSH) levels was observed, but 14 % of the children without palpable goitre also showed abnormal TSH levels.Given that the majority of subjects showed some degree of I deficiency and that children without goitre may have elevated TSH levels, the absence of goitre is an insufficient indicator to determine adequate I status. The risk of subsequent development of goitre, in the currently non-goitre population, is elevated. This suggests that short-term I supplementation should be considered independently of the presence of goitre or urinary I level, until the access to and consumption of iodised salt is generalised.

[Methemoglobin and osmoresistance of erythrocytes in patients with different types of goiter]

The purpose of this study was to determine the level of methemoglobin in the blood and osmoresistance of erythrocytes in patients with different types of goiter and control subjects. Investigated parameters indicate to the antioxidant status of human organism. We examined 12 healthy controls and 49 hyperthyroid patients: 17 patients with nodular goiter (mild thyrotoxicosis), 22 patients with diffuse toxic goiter (high level of thyrotoxicosis) and 10--with euthyroid nodule goiter. Osmoresistance of erythrocytes was measured by differential photoelectrocolorymetric method and methemoglobin--by spectroscopic method. We had received significant correlation between the level of methemoglobin, osmoresistance of erythrocytes and the degree of thyrotoxicosis. The results once again prove sensitivity of antioxidant status in response to toxicity, in particular against thyrotoxicosis.

[Current views on the etiopathogenesis of goiter in children]

The most frequent cause of goiter in children is a deficit of iodine, leading to endemia of goiter in the regions with insufficient supplementation of this element. Goiter occurs also in the course of autoimmunological diseases of the thyroid gland (Hashimoto disease, Graves' disease), genetically-related disorders of thyroid hormones, biosynthesis/impaired biosynthesis of thyroid hormones. According to the theory of goiter pathogenesis, excessive enlargement of the thyroid gland is due to adaptation of follicle cells of the gland aiming at neutralizing the impaired synthesis of the thyroid hormones caused by various intrathyroid, environmental and genetic factors/agents. The mechanisms stimulating thyrocytes to hyperplasia or hypertrophy are very complex and still unknown in spite of having identified many physiological and pathogenetic factors connected with goiter.

Transcription factor-mediated proliferation and apoptosis in benign and malignant thyroid lesions

Transcription factors play an essential role in regulating both cell proliferation and programmed cell death. Proliferation and apoptosis-related transcription factor immunoexpression patterns were concomitantly investigated in tissue sections of normal thyroid, goiters, follicular adenomas and well-differentiated papillary and follicular carcinomas using antibodies against prothymosin alpha, E2F-1, p53, Bcl2, and Bax proteins. Proliferation and apoptotic indices were determined by Ki-67 immunoreactivity and the terminal deoxynucleotidyl transferase-mediated deoxy uridine triphosphate nick-end labeling technique, respectively. Prothymosin alpha and E2F-1 immunoexpression levels were found to be significantly elevated in well-differentiated carcinomas compared to adenomas, goiters and normal tissues (P < 0.05). Both proteins were directly correlated with the proliferation index (P < 0.05). E2F-1 was additionally correlated with the apoptotic index (P < 0.05). The majority of cases were negative for p53 staining. Positive Bcl2 immunostaining was detected in all thyroid histotypes. None of the normal tissues showed Bax immunoreactivity, while positive accumulation differed significantly between hyperplastic and neoplastic histotypes. Direct correlations were observed between prothymosin alpha and Bcl2 as well as between E2F-1 and Bax immunoexpression (P < 0.05). These data demonstrate that prothymosin alpha and E2F-1 are strongly involved in the proliferation processes of thyroid neoplasias. Furthermore, prothymosin alpha may promote cell survival through the Bcl2 anti-apoptotic pathway, while E2F-1-induced apoptosis via p53-independent pathways may be associated with transcriptional activation of bax pro-apoptotic gene.

[Heart rate variability in patients with diffuse toxic goiter]

Functional state of the vegetative nervous system of 18 patients with first time diagnosed moderate thyrotoxicosis has been analyzed. Vegetative tonus, vegetative reactivity and vegetative activity during daily activity was assessed based on heart rate variability.

Exaggerated TSH responses to TRH in patients with goiter and 'normal' basal TSH levels

BACKGROUND/AIM

The availability of sensitive thyrotropin (TSH) assays decreased the diagnostic value of thyrotropin-releasing hormone stimulation tests (TRH-ST) in subclinical hypothyroidism. In this study we aimed to evaluate the relation between basal and stimulated serum TSH levels on TRH-ST and to determine the prevalence of patients with normal basal serum TSH and exaggerated TSH responses.

METHODS

179 patients (117 girls, 123 pubertal) with a median age of 12 (2.7-21.4) years who presented with goiter were enrolled and evaluated for their pubertal stage, height, thyroid autoimmunity, ultrasonography, thyroid function, and TRH-ST. Serum TSH concentrations were determined by sensitive assays. At TRH-ST, a peak serum TSH level >25 mIU/l was considered as an exaggerated response.

RESULTS

30 (17%) patients had an exaggerated TSH response. In patients with serum TSH levels between 2 and 4.68 mIU/l (upper half the normal range), an exaggerated TSH response was observed in 19.5%. A positive correlation between basal and TRH-stimulated TSH levels was determined (r = 0.536, p < 0.01). In patients with an exaggerated TSH response, 23 had normal (discordant) and 7 had high basal TSH levels (concordant). The mean basal serum TSH level was lower in the discordant group compared to the concordant group (p < 0.01).

CONCLUSION

Basal serum TSH levels might not be sufficient for diagnosing subclinical hypothyroidism. Stimulated TSH levels on TRH-ST are valuable, especially when serum TSH concentrations are in the upper half of the normal range.

Sympathetic nervous system activity in rat thyroid: potential role in goitrogenesis

The role of sympathetic innervation in regulation of thyroid function is incompletely understood. We, therefore, carried out studies in rats utilizing techniques of norepinephrine turnover to assess thyroid sympathetic activity in vivo. Thyroidal sympathetic activity was increased 95% by exposure to cold (4 degrees C), 42% by chronic ingestion of an iodine-deficient diet, and 32% in rats fed a goitrogenic diet (low-iodine diet supplemented with propylthiouracil). In addition, fasting for 2 days reduced sympathetic nervous system activity in thyroid by 38%. Thyroid growth and 125I uptake were also compared in intact and decentralized hemithyroids obtained from animals subjected to unilateral superior cervical ganglion decentralization. Unilateral superior cervical ganglion decentralization led to a reduction in thyroid weight, in 125I uptake by thyroid tissue, and in TSH-induced stimulation of 125I uptake in decentralized hemithyroids. These results suggest that sympathetic activity in thyroid contributes to gland enlargement and may modulate tissue responsiveness to TSH.

Immeasurably low and non-TRH-stimulatable TSH associated with normal I-123 uptake in two goitrous euthyroid patients: possible existence of other thyroid-hormone regulated thyroid stimulators other than TSH

We described two euthyroid patients with normally functioning goiters, but with persistently undetectable and non-stimulatable TSH levels. Subject 1 was a 64-year-old woman with a large diffuse goiter who has been clinically and biochemically euthyroid without any medication for at least 19 years. Subject 2 was a 31-year-old woman with a small diffuse goiter who has been euthyroid for 4 years. Both patients had persistently undetectable levels of serum TSH, TSH receptor antibodies (TRAb) and thyroid stimulating antibodies (TSAb). Their basal TSH levels were very low and their T3 responses to TRH were very diminished or absent. In contrast, the basal levels of the other pituitary hormones and their responses to LHRH, GRH and CRH stimulation were all within normal limits in both patients. MRI images of pituitary glands, 123I thyroid uptake, and thyroid scans were normal. Ectopic thyroids were not detected on (99m)TcO4- and 123I total body scans. Factors interfering with the measurement of TSH were excluded by recovery studies. In subject 1 a T3-suppression test was positive and a perchlorate discharge test was negative. In subject 2 a T3-suppression test was negative. Euthyroid Graves' disease, subclinical hyperthyroidism, destructive thyroiditis, thyrotoxicosis of extrathyroid origin, central hypothyroidism, and nonthyroidal illness were all ruled out by these observations. These results suggest that an unknown factor, such as thyrostimulin, but not TSH or TSAb, stimulates the thyroid and maintains euthyroidism, and may have a role in the regulation of the hypothalamus-pituitary-thyroid axis.

Impact of disease activity on thyroid diseases in patients with acromegaly: basal evaluation and follow-up

In patients with acromegaly, the exact incidence of thyroid disorders is still controversial and less is known about the impact of disease activity and successful treatment. To address this issue, we investigated 73 acromegalic patients (age 55 +/- 13 yr; mean +/- SD) by ultrasonography in comparison to an age-matched control group (54 +/- 1 yr) in the same moderate iodine deficient area (retrospective study). These non-acromegalic volunteers (n = 199) were examined in the same clinic during a thyroid screening test. At the time of examination, 52 (71.2 %) of the acromegalic patients were active, 17 (23.3 %) were cured, and 4 (5.5 %) were controlled with somatostatin analogues. The prevalence of goiter (normal range < 18 ml female, < 25 ml male) was significantly higher (82.2 %) in the mixed group of acromegalics (active, well controlled, cured; n = 73) and in the active group (90.4 %) than in the control group (n = 199, 18.1 %, p < 0.001). Thyroid nodules were found in 63.0 % of the mixed group of acromegalics and in 71.2 % of patients with active disease (33.1 % in controls, p < 0.001). (99 m)Tc scintigraphy revealed thyroid autonomy in 9/73 (12.3 %) and cold nodules in 19/73 (26.0 %) patients. Thyroid cancer was diagnosed in 4 (5.5 %) of acromegalic patients (3 papillary and 1 follicular carcinoma). We found a weak correlation between the disease duration and the initial thyroid volume (r = 0.54, p < 0.0056). Thirty-seven newly diagnosed acromegalics were followed over a period of 7.3 +/- 4.1 years. 5 (13.5 %) of these patients remained active, 8 (21.6 %) were controlled with somatostatin analogues, and 24 (64.9 %) were cured. The mean age, sex distribution, disease duration, prevalence of TSH-deficiency, and initial thyroid volume (46 +/- 11 ml in active, 42 +/- 7 ml in controlled, and 45 +/- 5 ml in cured patients) did not differ statistically between the three groups. In patients with active acromegaly, thyroid volume increased by 19.5 +/- 8.1 %. In contrast, thyroid volume decreased in the group of medically controlled and cured acromegalics (- 21.5 +/- 7.1 %; p < 0.005 and - 24.2 +/- 5.7 %; p < 0.002, respectively). No correlation was found between thyroid volume and TSH levels, levothyroxine and/or iodide administration neither in TSH sufficient nor in TSH insufficient patients. In conclusion, successful treatment of patients with active acromegaly decreases thyroid volume. Cold nodules and thyroid cancer frequently occur in acromegalic patients.

[The influence of treatment with substitutive or suppressive doses of thyroxine on biochemical bone turnover markers]

PURPOSE

Thyroid hormones belong to essential regulators of growth and remodelling of bones. The development of modern radioimmunological and immunoenzymatic methods opened the way to studies on the influence of exogenous thyroxine on the metabolism of osseous tissue. The activity of osteoblasts and the osteoclast ratio is a measure of the process termed "bone turnover" which can be assessed by determining concentrations of enzymes and bone matrix proteins in serum. The aim of this study was to evaluate the influence of a twelve-month regimen with substitutive or suppressive doses of thyroxine on bone alkaline phosphatase (BAP) concentrations in serum and deoxypyridoline (DPR) concentrations in the urine of women with hypothyroidism or with simple goitre.

MATERIAL AND METHODS

We enrolled 26 women with not-treated hypothyroidism (Group I) and 41 with not-treated simple goitre (group II). The age of the patients ranged from 29 to 66 years. Patients were qualified for treatment with substitutive (hypothyroidism) or suppressive (goitre) doses of thyroxine. Each group was divided into two subgroups: IA--15 premenopausal patients with hypothyroidism (mean age 41.53 +/- 1.39 years); IB--11 postmenopausal patients with hypothyroidism (mean age 53.18 +/- 1.66 years); IIA--24 premenopausal patients with simple goitre (mean age 39.71 +/- 0.98 years); IIB--17 postmenopausal patients with simple goitre (mean age 53.82 +/- 1.35 years). Evaluations of bone turnover markers in serum (BAP) and in twenty-four hour urine collection (DPR) and serum concentrations of TSH, FT3 and FT4 were carried out prior to treatment and after 1, 3, 6, 9 and 12 months ofthyroxine administration.

RESULTS

Bone turnover markers increased during treatment with substitutive or suppressive doses of thyroxine, especially in postmenopausal women.

CONCLUSIONS

1. Treatment with substitutive or suppressive doses of thyroxine stimulates osteogenic and osteoclastic processes in pre- and postmenopausal women. 2. Suppressive doses of thyroxine are more potent in increasing bone turnover than substitutive doses. 3. The osteoclastic process is more intense in postmenopausal women on substitutive or suppressive doses of thyroxine.

[The problem of goiter. Geoecological aspects]

The study determined the leading role of such geographic and geological factor as geological formations (mineralogical composition, structure, and the degree of metamorphism), tectonics, history of geological development, relief, and paleorelief in the microelementary status of the biosphere. The study proved that thyroimmunological profile of patients with goitre and geographic-and-geological conditions of the area are closely connected. The microelementary map of Bashkortostan regions was developed.

The effects of vitamin A deficiency and vitamin A supplementation on thyroid function in goitrous children

In developing countries, children are at high risk for both the iodine deficiency disorders (IDD) and vitamin A deficiency (VAD). The study aim was to determine the effects of VAD and vitamin A (VA) supplementation on thyroid function in an area of endemic goiter. In a double-blind, randomized, 10-month trial, Moroccan children with IDD and VAD (n = 138) were given iodized salt and either VA (200,000 IU) or placebo at 0 and 5 months. At 0, 5, and 10 months, measurements of VA status and thyroid function were made. At baseline, increasing VAD severity was a predictor of greater thyroid volume and higher concentrations of TSH and thyroglobulin (P < 0.001). In children with VAD, the odds ratio for goiter was 6.51 (95% confidence interval, 2.94, 14.41). VAD severity was also a strong predictor of higher concentrations of total T(4) (P < 0.001); the odds ratio for hypothyroidism in VAD was 0.06 (95% confidence interval, 0.03, 0.14). During the intervention, mean thyroglobulin, median TSH, and the goiter rate significantly decreased in the VA-treated group compared with those in the placebo group (P < 0.01). The findings indicate that VAD in severely IDD-affected children increases TSH stimulation and thyroid size and reduces the risk for hypothyroidism. This effect could be due to decreased VA-mediated suppression of the pituitary TSHbeta gene. In IDD- and VAD-affected children receiving iodized salt, concurrent VA supplementation improves iodine efficacy.

Fetal and neonatal thyroid function in relation to maternal Graves' disease

The abundance of published data on the neonatal effects of maternal Graves' disease (GD) contrasts with the paucity of information on fetal effects. In our yet unpublished study, we prospectively studied 72 pregnant women with a history of Graves' disease. Fetal ultrasonography was done at 22 and 32 weeks of gestational age. Fetal goiter was found at 32 weeks in 11 of the fetuses of the 41 mothers with positive TSH-receptor antibodies and/or antithyroid treatment and in none of the fetuses of the 31 other mothers. In the 11 fetuses with goiter, ultrasound findings (thyroid Doppler and bone maturation), fetal heart rate, and maternal antibody and antithyroid drug status effectively discriminated between hypothyroidism (n=7) and hyperthyroidism (n=4). One fetus with hyperthyroidism died in utero at 35 weeks from heart failure. Treatment was successful in the ten other fetuses. One fetus without goiter had moderate hypothyroidism at birth. This study showed that it is of the utmost importance to have the fetal thyroid scrutinized by an expert ultrasonographist and to have team work with obstetricians and paediatric endocrinologists in pregnant mothers with GD. This allowed us to accurately determine fetal thyroid status and to adapt the treatment in mothers successfully. Fetal hyperthyroidism does exist and needs an appropriate aggressive treatment.

The regulation of thyroid function during normal pregnancy: importance of the iodine nutrition status

The main change in thyroid function associated with the pregnant state is the requirement of an increased production of thyroid hormone that depends directly upon the adequate availability of dietary iodine and integrity of the glandular machinery. Physiologic adaptation takes place when the iodine intake is adequate, while this is replaced by pathologic alterations when there is a deficient iodine intake. Pregnancy acts typically, therefore, as a revelator of underlying iodine restriction. Iodine deficiency (ID) has important repercussions for both the mother and the fetus, leading to sustained glandular stimulation, hypothyroxinemia and goitrogenesis. Furthermore, because severe ID may be associated with an impairment in the psycho-neuro-intellectual outcome in the progeny-because both mother and offspring are exposed to ID during gestation (and the postnatal period), and because ID is still prevalent today in several European countries-it has been proposed already in the early 1990s that iodine supplements be given systematically to pregnant and breast-feeding women. Particular attention is required to ensure that pregnant women receive an adequate iodine supply, by administering multivitamin tablets containing iodine supplements, in order to achieve the ideal recommended dietary allowance of 200-250 microg iodine/day.

Localization and functional studies of pendrin in the mouse inner ear provide insight about the etiology of deafness in pendred syndrome

Immunolocalization studies of mouse cochlea and vestibular end-organ were performed to study the expression pattern of pendrin, the protein encoded by the Pendred syndrome gene (PDS), in the inner ear. The protein was restricted to the areas composed of specialized epithelial cells thought to play a key role in regulating the composition and resorption of endolymph. In the cochlea, pendrin was abundant in the apical membrane of cells in the spiral prominence and outer sulcus cells (along with their root processes). In the vestibular end-organ, pendrin was found in the transitional cells of the cristae ampullaris, utriculi, and sacculi as well as in the apical membrane of cells in the endolymphatic sac. Pds-knockout (Pds-/-) mice were found to lack pendrin immunoreactivity in all of these locations. Histological studies revealed that the stria vascularis in Pds-/- mice was only two-thirds the thickness seen in wild-type mice, with the strial marginal cells showing irregular shapes and sizes. Functional studies were also performed to examine the role of pendrin in endolymph homeostasis. Using double-barreled electrodes placed in both the cochlea and the utricle, the endocochlear potential and endolymph potassium concentration were measured in wild-type and Pds-/- mice. Consistent with the altered strial morphology, the endocochlear potential in Pds-/- mice was near zero and did not change during anoxia. On the other hand, the endolymphatic potassium concentration in Pds-/- mice was near normal in the cochlea and utricle. Together, these results suggest that pendrin serves a key role in the functioning of the basal and/or intermediate cells of the stria vascularis to maintain the endocochlear potential, but not in the potassium secretory function of the marginal cells.

Follicular carcinoma of the thyroid with hyperthyroidism. A case report

BACKGROUND

Follicular carcinoma of the thyroid in association with hyperthyroidism is rare. The malignant lesion may remain occult for a long time. Certain clinical and cytologic features may be helpful in raising the alarm.

CASE

An elderly male with a history of occupational exposure to X rays, long-standing toxic multinodular goiter and clinical hyperthyroidism presented with a rapidly enlarging mass in the neck. Cytologic smears showed a prominent microfollicular pattern, scanty colloid, anisonucleosis and nuclear overlapping. The noteworthy feature was the presence of marginal vacuoles. The cytologic diagnosis of follicular neoplasm with highly suggestive malignancy was made. Subsequently, multiple pulmonary nodules provided radiologic evidence of possible metastatic spread.

CONCLUSION

This case report demonstrates the rare association of follicular carcinoma of the thyroid with hyperthyroidism and analyzes certain high-risk clinical and cytologic features to be considered in the follow-up of long-standing hyperfunctioning multinodular goiter.

Left ventricular systolic and diastolic functions in children living in a moderate-severe iodine deficiency area

Although the effects of impaired thyroid functions on the cardiovascular system is well known, there is no report investigating left ventricular functions in children with iodine deficiency. We evaluated left ventricular functions in children living in a moderate-severe iodine deficient area of northern Turkey. Of 40 children, 13 had stage I, 19 had stage II and eight had stage III goiter. None of the children had clinical signs of hypothyroidism, hyperthyroidism or cardiac dysfunction. Urinary iodine concentration decreased significantly from mild (Group 1) to moderate (Group 2) and severe (Group 3) iodine deficient groups (p <0.05). Mean serum free T3 levels did not differ significantly between the groups. However, a significant difference in mean serum free T4 level was found between Groups 1 and 2 (p <0.05), but remained in the normal range. Although the mean serum TSH level differed significantly between Group 1 and Group 3 and Group 2 and Group 3 (p <0.05), mean values were in the normal range. Mean left ventricular ejection fraction, shortening fraction and diastolic filling parameters did not differ significantly between groups. In conclusion, in case of preserved thyroid hormone levels, a moderate-severe iodine deficiency does not seem to affect left ventricular functions.

Orthopnea and tidal expiratory flow limitation in patients with euthyroid goiter

BACKGROUND

Nontoxic goiters can cause extrathoracic upper airway obstruction and, if large, may extend into the thorax, causing intrathoracic airway obstruction. Although patients with goiter often report orthopnea, there are few studies on postural changes in respiratory function in these subjects.

PURPOSE

The aim of this study was to investigate the postural changes in respiratory function and the presence of flow limitation (FL) and orthopnea in patients with nontoxic goiter.

METHODS

In 32 patients with nontoxic goiter, respiratory function was studied in seated and supine position. Expiratory FL was assessed with the negative expiratory pressure method. Goiter-trachea radiologic relationships were arbitrarily classified as follows: grade 1, no evidence of tracheal deviation; grade 2, tracheal deviation present in lateral and/or anteroposterior plane but with tracheal compression < 20%; and grade 3, tracheal deviation present with compression > 20%. Subgroups were considered according to this classification and occurrence of orthopnea and FL.

RESULTS

In all three groups of patients, the average maximal expiratory flow at 50% of FVC/maximal inspiratory flow at 50% of FVC ratios were > 1.1, suggesting the presence of upper airway obstruction. Grade 3 patients had a significantly lower expiratory reserve volume and maximal expiratory flow at 25% of FVC and higher airway resistance and 3-point FL score than patients with grade 1 and grade 2. The prevalence of orthopnea was highest in patients with grade 3 (75%, as compared to 18% in the grade 1 group). In patients with orthopnea, the prevalence of intrathoracic goiter was also higher (78%, vs 21% in patients without orthopnea).

CONCLUSION

There is a high prevalence of orthopnea in patients with goiter, especially when the location is intrathoracic and causes a reduction of end-expiratory lung volume and flow reserve in the tidal volume range, promoting FL especially in supine position. Obesity is a factor that increases the risk of orthopnea in patients with goiter.

[Preoperative analysis of vital lung capacity in female patients with flattened thyrotoxicosis]

Unbalanced hyperthyroidism leads to the feeling of dyspnea and to the decrease of vital lung capacity. Efficacious treatment of thyrotoxicosis relieves mentioned disorders and brings normalization of ventilation parameters. The main issue of this research was the analysis of vital lung capacity in female patients with properly treated hyperthyroidism and comparison of values of these parameters among patients with balanced thyrotoxicosis, non-toxic goitre and with non-thyroid disorders. Research was conducted on 300 randomized female-patients (ASA I, II), aged 18 to 47 with surgically treated hyperthyroidism, non-toxic goitre or non-thyroid disorders. Vital lung capacity (VLC) was analyzed as absolute values and as a percent of predicted values. Statistical analysis revealed that patients in specified groups did not differ in age, weight and frequency of belonging to both ASA categories. Vital lung capacity and percent of predicted values were not significantly different in all groups. Vital lung capacity of female-patients with balanced hyperthyroidism did not differ significantly from vital lung capacity of patients with non-toxic goitre and non-thyroid disorders.

Prevalence of goiter in schoolchildren--a study on the influence of adequate iodine prophylaxis in Poland

Poland has been known as an area with iodine deficiency. Surveys carried out in 1992/1993 and 1994 revealed that the voluntary model of iodine prophylaxis introduced in 1986 was ineffective. In 1997 a new model of iodine prophylaxis based on obligatory household salt iodization has been implemented. In order to assess its effectiveness new studies were undertaken in 1999-2001. The study involved 1471 school-children aged 6-15 years from 12 sites. In every subject thyroid volume by means of ultrasound and urinary iodine concentration were assessed. The results were compared with data obtained from the same schools in the 1992/1993 survey. Between 1992/93 and 1999/2001 goiter prevalence decreased from 14.5% to 5.2% (p<0.05) and median urinary iodine concentration increased from 56 microg/l to 103 microg/l (p<0.05). A decrease in goiter prevalence was observed in 6 sites with moderate goiter endemia, whereas the changes in goiter prevalence were statistically insignificant in other 6 sites. Three sites were characterized by goiter prevalence close to 5% before and after implementing the obligatory model of iodine prophylaxis. Goiter prevalence in the remaining three sites remained within the same limit of 7-10%, in spite of observed ioduria increase. The Authors conclude that the Polish model of obligatory iodine prophylaxis ensures efficient iodine supplementation and this is confirmed by a significant increment in ioduria. The effect of this model on thyroid volume is evident in moderate goiter endemia areas. Slight changes in goiter prevalence in mild goiter endemia regions need further monitoring and considering other factors affecting thyroid volume.

[Goiters and thyroid function disorders in pregnancy]

Thyroid function abnormalities during pregnancy can affect up to 10% of all women. The mother's thyroid dysfunctions have an influence on fetal development, not only iodine deficiency, but also hyperthyroidism, hypothyroidism, and immunological disorders or inappropriate production of hCG. This review focuses on all thyroid dysfunctions during pregnancy.

[Effects of three different iodine interventions on the speed of normalization of enlarged thyroid gland due to iodine deficiency]

OBJECTIVE

To compare the effects of three different iodine interventions on the speed of normalization of enlarged thyroid gland.

METHODS

Schoolchildren aged 8 - 10 years were randomized divided into one of three groups: group A was given iodized salt by researchers with an iodine concentration of 25 mg/kg; group B used iodized salt purchased from the market; and group C was similar to group B with additional intake of iodized oil capsules containing 400 mg iodine at the beginning of the study. Salt iodine content was measured bimonthly for 18 months and indicators of iodine deficiency were measured at baseline and 6, 9, 12 and 18 months thereafter.

RESULTS

The prevalence of goiter measured by ultrasound, based on the World Health Organization (WHO) body surface area reference > 97(th) percentile, was 18% at baseline and declined to less than 5% by 12 month in groups A and C respectively, and to 9% after 18 months in group B. Rates of goiter were similar by palpation or by ultrasound. The median urinary iodine was 94 micro g/L at baseline and increased in all groups to > 200 micro g/L at the 6-month follow-up.

CONCLUSIONS

In this sample of schoolchildren with initially low or moderate level of iodine deficiency, the group receiving salt with 25 mg/kg (group A) recovered from iodine deficient on all indicators after 18 months of study. However when the iodine content of salt was floating, as seen in group B, the sizes of thyroid did not yet achieve normal status by 18 months.