How often should patients be reviewed after treatment with iodine-131 for thyrotoxicosis?

Six to 18 years after treatment with iodine-131 for thyrotoxicosis 69 euthyroid patients with raised serum thyrotrophin (TSH) concentrations (mean 25.0 +/- SE 2.0 mU/l) and 61 with normal concentrations (mean 4.0 +/- 0.2 mU/l) were included in a prospective five-year follow-up study beginning in 1972. During this period 13 patients from the original group with raised serum TSH concentrations became hypothyroid. In contrast it was five years before hypothyroidism developed in a single patient from the group with normal serum TSH concentrations in 1972, although raised concentrations were recorded in 19 of these patients during the study.     

Serum thyrotrophin concentration: an unreliable test for detection of early hypothyroidism after thyroidectomy.

Three groups of patients who had undergone subtotal thyroidectomy for Graves''s disease, toxic multinodular goitre, or euthyroid multinodular goitre 12 to 15 years before and in whom a normal serum thyroxine (T-4) level was found were each divided into two subgroups on the basis of a normal or a raised serum thyrotrophin concentration. There was no difference in mean serum T-4 concentration between patients with normal and those with raised serum thyrotrophin concentrations, and the values were similar to the mean T-4 values of the normal population. The mean serum triiodothyronine values of all groups were higher than normal, but the mean values of the groups with a normal and a raised serum thyrotrophin were similar. After thyroidectomy a mildly raised serum thyrotrophin does not in itself indicate the presence of hypothyroidism.     

Undetectable levels of tumor necrosis factor-alpha,nitric oxide and inadequate expression of inducible nitric oxide synthase in congenital hypothyroidism

OBJECTIVE: To analyse the production of TNF-alpha and NO in euthyroid and hypothyroid newborns. PATIENTS: A cross-sectional study was conducted involving 10 newborns diagnosed with primary congenital hypothyroidism (CH; group A) and 10 euthyroid children (group B). RESULTS: There were undetectable plasma levels of TNF-alpha and NO in the hypothyroid children, however plasma levels of TNF-alpha (5.5 0.5 pg/ml) and NO (5.6 1.7 microM) were detected at normal levels in all euthyroid children. Moreover, expression of iNOS mRNA in PBMC, determined by RT-PCR, was negative in both groups of infants. CONCLUSION: TNF-alpha and NO production are both impaired in hypothyroid newborns. We report for the first time evidence of undetectable levels of TNF-alpha and NO in infants with CH.     

Epidemiologic Characteristics and Risk Factors for Congenital Hypothyroidism from 2009 to 2018 in Xiamen,China

Objective: Early diagnosis and treatment of children with congenital hypothyroidism (CH) through newborn screening can effectively prevent delayed development. This study was designed to investigate the pathogenesis and factors that influence CH in urban areas of China between 2009 and 2018.Methods: A retrospective analysis of newborn screening data and diagnosis and treatment information for CH diagnosed in the information database of the neonatal disease screening center in one of China's five special economic zones from 2009 to 2018.Results: Of the 947,258 newborns screened between 2009 and 2018, 829 (406 girls) were diagnosed with CH at birth (1 diagnosis/1,136 births). Among the 608 cases of CH diagnosed at birth and re-evaluated at the age of 3 years, 487 were permanent congenital hypothyroidism (PCH, 1/1,429), and 121 were transient congenital hypothyroidism (TCH, 1/5,882). A total of 83.2% of infants with PCH (405/487) underwent thyroid imaging in the neonatal period, of which thyroid dysgenesis accounted for 28.64% (116/405) and functional defects accounted for 71.36% (289/405). The incidence of CH changed significantly in infants with initial serum thyroid-stimulating hormone concentrations of 41 to 100 mIU/L and ≥100 mIU/L, whereas the incidence of mild CH showed a slight increase. The incidence of CH was significantly higher in postterm infants (1/63) and low-birth-weight infants (1/370).Conclusion: In the past decade, the incidence of CH has increased, mainly due to the increase in the incidence of PCH and TCH. The incidence of mild CH has increased slightly. Postterm birth and low birth weight are important factors affecting the incidence of CH.Abbreviations: CH = congenital hypothyroidism; FT4 = free thyroxine; L-T4 = levothyroxine sodium; PCH = permanent congenital hypothyroidism; TCH = transient congenital hypothyroidism; TSH = thyroid-stimulating hormone; TT4 = total thyroxine     

Relation between biochemical severity and intelligence in early treated congenital hypothyroidism: a threshold effect.

OBJECTIVES--To assess whether early treatment of congenital hypothyroidism fully prevents intellectual impairment. DESIGN--A national register of children with congenital hypothyroidism who were compared with unaffected children from the same school classes and matched for age, sex, social class, and first language. SETTING--First three years (1982-4) of a neonatal screening programme in England, Wales, and Northern Ireland. SUBJECTS--361 children with congenital hypothyroidism given early treatment and 315 control children. MAIN OUTCOME MEASURES--Intelligence quotient (IQ) measured at school entry at 5 years of age with the Wechsler preschool and primary scale of intelligence. RESULTS--There was a discontinuous relation between IQ and plasma thyroxine concentration at diagnosis, with a threshold at 42.8 nmol/l (95% confidence interval 35.2 to 47.1 nmol/l). Hypothyroid children with thyroxine values below 42.8 nmol/l had a mean IQ 10.3 points (6.9 to 13.7 points) lower than those with higher values and than controls. None of the measures of quality of treatment (age at start of treatment (range 1-173 days), average thyroxine dose (12-76 micrograms in the first year), average thyroxine concentration during treatment (79-234 nmol/l in the first year), and thyroxine concentration less than 103 nmol/l at least once during the first year) influenced IQ at age 5. CONCLUSIONS--Despite early treatment in congenital hypothyroidism the disease severity has a threshold effect on brain development, probably determined prenatally. The 55% of infants with more severe disease continue to show clinically significant intellectual impairment; infants with milder disease show no such impairment. The findings predict that 10% of early treated infants with severe hypothyroidism, compared with around 40% of those who presented with symptoms in the period before screening began, are likely to require special education.     

Human epidermal growth factor concentrations in urine, but not in saliva and serum, depend on thyroid state

To evaluate the effects of thyroid hormones on the concentration of epidermal growth factor (EGF), we determined values for the immunoreactive EGF concentration in the urine (U-irEGF) of newborn infants with congenital hypothyroidism (N = 19), and in urine, saliva and serum of adult patients with hypothyroidism (N = 11) and hyperthyroidism (N = 8). The values were expressed as SD score (SDS), i.e. deviation in SD units from their mean value of healthy subjects of the same age and sex. The SDS of relative U-irEGF (ng/mg creatinine) was lower (P less than 0.01) in newborn infants with congenital hypothyroidism (-0.8 +/- 0.2; mean +/- SEM) than in healthy infants. Their relative U-irEGF correlated with their serum T4 concentrations (r = 0.59, P less than 0.01). The SDS of relative U-irEGF was lower (P less than 0.01) in adult hypothyroid patients (-1.2 +/- 0.5) and higher (P greater than 0.05) in adult hypothyroid patients (0.9 +/- 0.6) than in healthy adult subjects. When subsequently euthyroid, their SDS of relative U-irEGF increased to -0.5 +/- 0.3 (P less than 0.01), and decreased to -0.7 +/- 1.1 (P less than 0.05), respectively. The irEGF concentrations in saliva and serum were not significantly different between the hypothyroid and hyperthyroid patients. Our results indicate that urinary excretion of irEGF in man is dependent on thyroid hormone.     

Thyroid Function in Patients Treated with Radioactive Iodine for Thyrotoxicosis

A series of 105 patients treated at least two years earlier with radioactive iodine for thyrotoxicosis have been surveyed. Eighty-five patients (81%) were euthyroid clinically and on the basis of routine thyroid function tests. Of the euthyroid patients 46 (54%) had normal thyroid-stimulating hormone (TSH) levels and 39 (46%) had raised TSH levels. There was no difference in serum triiodothyronine levels between these two groups but the serum protein bound iodine and serum thyroxine, though still well within the normal range, were significantly lower in the group with raised TSH levels. The serum cholesterol was also significantly higher in this latter group.Most of the euthyroid patients were seen again a year later. None had become hypothyroid and neither those with normal nor those with raised TSH levels showed any evidence of a decline in the level of serum thyroxine.It is concluded that raised serum TSH levels in patients treated with iodine-131 are not necessarily indicative of hypothyroidism. There is no indication that patients who have this abnormality become overtly hypothyroid over a 12-month follow up.     

Natural history of autoimmune thyroiditis.

One hundred and sixty-three asymptomatic people with thyroid antibodies or raised serum thyrotrophin (TSH) concentrations, or both, and 209 age-matched and sex-matched controls without either marker of thyroid disorder were followed up for four years to determine the natural history of autoimmune thyroiditis. Mildly raised TSH concentrations alone and the presence of thyroid antibodies alone did not significantly increase the risk of developing overt hypothyroidism during the four years compared with the controls. Overt hypothyroidism developed at the rate of 5% a year in women who initially had both raised TSH concentrations and thyroid antibodies. Prophylactic treatment with thyroxine may be justified in women found to have both markers of impending thyroid failure. The cost effectiveness of screening the adult population remains to be evaluated.     

Diagnostic value of thyrotrophin releasing hormone tests in elderly patients with atrial fibrillation.

A prospective study was carried out to compare clinical and biochemical thyroid states with responses of thyroid stimulating hormone (TSH) to thyrotrophin releasing hormone (TRH) in elderly patients with either atrial fibrillation (n = 75; mean age (SD) 79.3 (6.0) years) or sinus rhythm (n = 73; mean age 78.4 (5.6) years) admitted consecutively to the department of geriatric medicine. No patient in either group had symptoms or signs of hyperthyroidism. Overall, the TSH responses to TRH did not differ significantly between the two groups. Ten (13%) of the patients with atrial fibrillation (of whom four had raised thyroid hormone concentrations) and five (7%) of the patients with sinus rhythm showed no TSH response to TRH while 26% of each group (20 and 19 patients, respectively) showed a much reduced response. Only one of 13 patients with apparently isolated atrial fibrillation showed no TSH response to TRH, and none of these 13 patients was hyperthyroid. In particular, three patients (two with atrial fibrillation and one with sinus rhythm) who showed no TSH response to TRH at presentation exhibited a return of TSH response to TRH at follow up six weeks later. In conclusion, reduced or absent TSH responses to TRH are common in sick elderly patients whether they have atrial fibrillation or sinus rhythm and whether they are euthyroid or hyperthyroid biochemically. An absence of response is therefore an uncertain marker of hyperthyroidism in these groups of patients, and diagnosis and ablative treatment should be based at least on the presence of raised circulating free triiodothyronine or free thyroxine concentrations, or both.     

Neonatal screening for congenital hypothyroidism by measurement of plasma thyroxine and thyroid stimulating hormone concentrations.

Neonatal screening for congenital hypothyroidism was introduced in the City of Birmingham in 1980 by measuring concentrations of both thyroid stimulating hormone and thyroxine in plasma. Over two years 30 108 babies were tested. Thirty one babies were recalled because of thyroid stimulating hormone concentrations greater than 40 mU/l, of whom 12 were treated with replacement thyroxine. Six babies were found to have low thyroxine concentrations because of reduced thyroxine binding globulin and five raised thyroxine values because of increased thyroxine binding globulin. As a result of this study screening was continued with measurement of thyroid stimulating hormone only as the primary test for congenital hypothyroidism, the thyroxine value being measured only when the concentration of thyroid stimulating hormone exceeded 20 mU/l.     

Survey of neonatal screening for primary hypothyroidism in England,Wales, and Northern Ireland 1982-4

National screening for congenital hypothyroidism was established in the United Kingdom in 1982. During 1982-4, 488 infants with primary congenital hypothyroidism were detected by the 25 regional screening laboratories in England, Wales, and Northern Ireland. In addition, one infant had signs of cretinism at birth and was investigated before the screening test was done and four infants were known to have been missed by the screening programme; among these four infants the initial thyroid stimulating hormone concentrations were normal in two with inherited defects of synthesis of thyroxine, not measured in one, and false negative in one. The overall incidence of primary hypothyroidism was 1:3937 births (boys 1:6640, girls 1:2756). The incidence seemed to be reduced in infants born to black mothers (two cases only) and increased in those born to Asian mothers (61 cases). Congenital anomalies other than those of the thyroid gland were reported in 36 children (7%), and 15 (3%) died from various causes before the age of 4. Infants who were considered to show unequivocal evidence of hypothyroidism started treatment at a median age of 17 days (5th and 95th centiles 10 and 42 days) compared with a median age of 14 days (5th and 95th centiles 9 and 21 days) for infants with classic phenylketonuria also detected by national screening.     

Congenital anomalies associated with congenital hypothyroidism

The French national neonatal screening program for congenital hypothyroidism (CH) was initiated in 1978. The purpose of this study was to ascertain the incidence of congenital extrathyroid anomalies (ETAs) among the infants with congenital hypothyroidism (CH) and to compare it with the Northeastern France Birth Defect Monitoring System data from 1979 to 1996. Among 129 CH infants on whom adequate data were available, 20 infants (15.5%) had associated congenital anomalies. Eight out of 76 infants with persistent CH had ETAs (10.5%) whereas 12 out of 53 children with transient hypothyroidism had ETAs (22.6%, p < 0.05). Some additional anomalies were considerably more common than in the general population. Nine infants had congenital cardiac anomalies (6.9%). This rises the question if teratogenic effects active during organogenesis may affect simultaneously many organs, including the developing thyroid, causing a relatively high percentage of CH infants with congenital ETAs.     

Growth,development, and reassessment of hypothyroid infants diagnosed by screening.

Thirty]six neonates in whom hypothyroidism was diagnosed after thyroid stimulating hormone screening were reassessed at 1 year. All had grown satisfactorily and the mental development scores were normal in all except two. Treatment was withdrawn in 32 and persistent hypothyroidism was confirmed in 31 cases. Thyroid stimulating hormone concentrations were raised in one-third of cases before the withdrawal of treatment and this was associated with generally lower concentrations of serum thyroxine (T4) and smaller doses of L-thyroxine than in those cases with normal concentrations of thyroid stimulating hormone. In treating congenital hypothyroidism, serum T4 concentrations should be monitored regularly and the dose of thyroxine adjusted to maintain serum T4 in the upper part of the reference range.     

Poor growth in school entrants as an index of organic disease: the Wessex growth study.

OBJECTIVE--To establish whether poor height or height velocity, assessed during the year of school entry, might identify children with previously undiagnosed organic disease. DESIGN--Observation of a total population and their case controls. SETTING--Community base. SUBJECTS--All 14,346 children in two health districts entering school during two consecutive years were screened for height by school nurses, and those whose height lay below the 3rd centile according to Tanner and Whitehouse standards (n = 180) were identified. After excluding 32 with known organic disease, five from ethnic minorities, and three who refused to take part, the remaining 140 short normal children were matched with 140 age and sex matched controls of average height (10th-90th centile) and their height velocities over 12 months measured. MAIN OUTCOME MEASURES--Height, height velocity, previously diagnosed organic disease, and organic disease diagnosed as a result of blood tests and specialist examination. RESULTS--Twenty five of the 180 short children (14%) were already known to have chronic organic disease which could explain their poor growth. Blood tests and specialist examination revealed a further seven with organic disease, which was acquired rather than congenital in three, and a second cause of short stature in one with known organic disease. These eight conditions had been missed at the school entry medical examination. The shorter the child, the more likely an underlying organic disorder, with seven of the 12 children whose heights were more than 3 standard deviations below the mean having some organic disease. Height velocity measured over 12 months, however, did not distinguish short normal children from those with disease or from their matched controls. CONCLUSIONS--Height, but not height velocity, is a useful index for identifying unrecognised organic disease at school entry. The shorter the stature the greater the prevalence of organic disease. The frequency of newly diagnosed remediable disease in this study (1 in 3-4000) is similar to that of neonatal hypothyroidism, which is routinely screened for. Routine investigation of all very short school entrants is recommended.     

Long-term outcome by method of delivery of fetuses in breech presentation at term: population based follow up.

OBJECTIVE--To compare the long-term outcome of infants delivered in breech presentation at term by intended mode of delivery. DESIGN--A population based comparison of outcomes up to school age. Data obtained from maternity, health visitor, and school medical records and handicap register. SETTING--Grampian region 1981-90. SUBJECTS--1645 infants delivered alive at term after breech presentation. MAIN OUTCOME MEASURES--Handicap, developmental delay, neurological deficit, psychiatric referral. RESULTS--Elective caesarean section was performed in 590 (35.9%) cases. The remainder (1055; 64.1%) were intended vaginal deliveries. Handicap or other health problem was recorded in 269 (19.4%) of 1387 infants for whom records were available. Proportions of elective caesarean sections and intended vaginal deliveries in this group were 37.2% (100 cases) and 62.8% (169) respectively, almost the same as in the total cohort. There were no significant differences between elective caesarean section and planned vaginal delivery in terms of severe handicap or any other outcome measure. Case records were obtained for 23 of 27 infants with severe handicap. 11 (47.8%) were delivered by elective caesarean section. Of these, three had undiagnosed congenital abnormalities and seven were unexplained. Of the 12 (52.2%) planned vaginal deliveries, in only one was handicap possibly attributable to delivery and four cases were unavoidable even if elective caesarean section had been planned. CONCLUSION--In selected cases of breech presentation at term planned vaginal delivery with caesarean section if necessary remains as safe as elective caesarean section in terms of long term handicap. It was not possible to determine whether particular babies would have fared better had they been delivered by elective caesarean section.     

Neonatal thyroid-stimulating hormone screening as an indirect method for the assessment of iodine deficiency in Estonia

According to neonatal thyroid screening the incidence of congenital hypothyroidism in Estonia is 1:2,860. Transient hyperthyrotropinemia with a raised thyroid-stimulating hormone level of 5 microU/ml occurred in 17.7% of infants and was not associated with low birth weight, small birth length, low gestational age or congenital anomalies. Based on WHO criteria (WHO/UNICEF, 1994) it corresponds to mild iodine deficiency in Estonia (3% or less is in iodine-sufficient areas). This is in agreement with the previously reported median urinary iodine content of 65 microg/l in children. The frequency of infants with TSH >5 microU/ml was 16.4, 21 and 17. 2% in three regions (north, central and south) of Estonia, respectively, indicating mild to moderate iodine deficiency. These findings show the possibility of using the results of newborn screening for congenital hypothyroidism to assess the severity of iodine deficiency in Estonia. The introduction of universal iodine prophylaxis is recommended.     

Treatment of amiodarone induced hyperthyroidism with potassium perchlorate and methimazole during amiodarone treatment.

To exploit the antiarrhythmic effect of amiodarone when patients develop the side effect of thyrotoxicosis three patients with hyperthyroidism induced by amiodarone were given simultaneously 1 g potassium perchlorate a day for 40 days and a starting dose of 40 mg methimazole a day while they continued to take amiodarone. As hyperthyroidism might have recurred after potassium perchlorate treatment was stopped the dose of methimazole was not reduced until biochemical hypothyroidism (raised thyroid stimulating hormone concentrations) was achieved. The patients became euthyroid (free triiodothyronine concentration returned to normal values) in two to five weeks and hypothyroid in 10 to 14 weeks. One patient became euthyroid while taking 5 mg methimazole a day and 600 mg amiodarone weekly; the two others required substitution treatment with thyroxine sodium while taking 5 mg methimazole or 50 mg propylthiouracil (because of an allergic reaction to methimazole) and 2100 or 1400 mg amiodarone weekly. Hyperthyroidism induced by amiodarone may be treated with potassium perchlorate and methimazole given simultaneously while treatment with amiodarone is continued.     

Neurodevelopmental outcome in babies weighing less than 2001 g at birth.

From 1976 to 1980, 1034 infants with birth weights of 500-2000 g were cared for in the neonatal medical unit; 724 were discharged. Twenty (2.8%) subsequently died and 654 (90.3%) were followed up at a median age of 3 years 3 months. Fifty five (7.6%) survivors had major neurodevelopmental handicaps not attributable to congenital anomalies. Increasing prevalence of major handicap was found with decreasing birth weight and gestation. Children with birth weights of less than 1251 g had a higher incidence of all major disabilities. Handicapped children with a birth weight less than 1251 g were more likely to have blindness, deafness, multiple disabilities, and more severe cerebral palsy. There were 146 (20.2%) children with minor disabilities: neurological impairments (n = 11), borderline results on psychometric testing (n = 18), visual impairments (n = 52), hearing impairments (n = 40), and speech impairments (n = 71). Children weighing less than 1251 g at birth had a higher incidence of minor visual and hearing impairments. In 389 children the mean Griffiths quotient was 101.6 (SD 17.2) (range 50-147), and 158 children had a mean Wechsler preschool and primary intelligence quotient of 101.8 (13.2) (range 56-127): these quotients did not vary with birth weight or gestation but did vary with socioeconomic group, schooling, and family structure. During the study period an improving prognosis in terms of both survival and handicap was observed in children weighing less than 1251 g at birth.     

Multivariate analysis on factors affecting suppression of thyroid-stimulating hormone in treated congenital hypothyroidism

AIMS: To determine the factors which influence the suppression of thyroid-stimulating hormone (TSH) in infants with congenital hypothyroidism (CH) following treatment. METHODS: We examined retrospectively the patterns of thyroid function tests from diagnosis to 3 years of age in 140 infants diagnosed with CH from screening. Patients were classified into 3 groups: athyreosis, ectopia and presumed dyshormonogenesis on the basis of thyroid scans. Adequate TSH suppression was defined as plasma TSH concentration <6 mU/l. The factors affecting the suppression of TSH at 6 months and 1 year of age which were evaluated were: initial confirmatory plasma TSH, initial plasma thyroxine (T4), mean age of starting treatment with L-T4, dose of L-T4 at diagnosis, 6 weeks, 3 months and 6 months, and aetiology of the congenital hypothyroidism. Variables were then entered in a stepwise logistic regression model for TSH suppression at 6 months and 1 year of age. RESULTS: All infants had radionuclide scans prior to treatment: athyreosis (n = 39), ectopia (n = 78) and dyshormonogenesis (n = 23). 58% of patients had persistently raised TSH at 6 months of age while 31% of patients had a persistently raised TSH at 1 year of age. There was a significant delay in the normalisation of plasma TSH in athyreosis and ectopia groups compared with dyshormonogenesis. Multiple regression analysis for TSH suppression at 6 months of age found plasma T4 levels and aetiology of CH as independent factors affecting the timing of TSH suppression. Aetiology of CH was the only independent factor affecting TSH suppression at 1 year of age. CONCLUSION: At 6 months of age, plasma T4 levels at 6 weeks and 3 months, and aetiology of CH were independent factors affecting timing of TSH suppression. However, by 1 year of age, the aetiology of CH was the only independent factor affecting suppression of TSH.     

Neonatal skeletal maturation in congenital hypothyroidism and its prognostic value for psychomotor development at 3 years in patients treated early

Neonatal skeletal maturation was assessed by different methods based on the bone centres in the knee and ankle region in 46 infants with true-positive (patients) and 17 infants with false-positive screening tests (controls). The patients and controls did not differ in mean age at X-ray examination and age at the start of treatment (14.5 +/- 5.7 days). One of the methods used to score the size of femoral and tibial epiphyses was just as good as the other ones tested, but has the advantage of being the easiest to use and therefore clinically most suitable. Skeletal maturity assessed by this method correlated best with serum T4 (r = 0.62, p less than 0.01). Griffiths tests were performed in 37 of the 46 patients at 28-48 months of life. The best correlation obtained between neonatal skeletal maturity and Griffiths global developmental quotient at 3 years of age was r = 0.58 (p less than 0.001). Although statistically significant, it was too weak to be of clinical value in identifying individual patients at risk. We conclude that an assessment of skeletal maturation is not useful for the prognosis of psychomotor development in individual patients with congenital hypothyroidism receiving treatment within the first 2 weeks of life.