Lack of effect of thyroid hormone on diabetic rat heart function and biochemistry

Cardiac functional abnormalities are frequently seen in diabetics and diabetes is also known to produce a state of mild hypothyroidism. To study the degree of involvement of diabetes-induced hypothyroidism on altered myocardial function, thyroid replacement therapy was carried out in streptozotocin-diabetic rats. Triiodothyronine (T3) treatment was initiated 3 days after the rats were made diabetic and was carried out for 6 weeks thereafter. Isolated perfused hearts from diabetic rats exhibited a depression in left ventricular developed pressure and positive and negative dP/dt at higher filling pressures as compared with controls. The depression could not be prevented by thyroid treatment. Calcium uptake activity in the cardiac sarcoplasmic reticulum (SR) was also depressed as a result of diabetes and this depression also was not prevented by thyroid treatment. Long chain acyl carnitine levels were found to be elevated in diabetic cardiac SR and could not be lowered by T3 treatment. The results indicate that the myocardial dysfunction observed in diabetic rats is due to factors other than the induced hypothyroidism.     

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.     

Rhabdomyolysis and Peroneal Nerve Compression Associated With Thyroid Hormone Withdrawal in the Setting of Remnant Ablation: Review of the Literature

ObjectiveTo review the putative mechanisms whereby hypothyroidism is associated with severe myopathy, neural injury, and acute compartment syndrome and report a case of nontraumatic common peroneal nerve compression associated with hypothyroidism-induced rhabdomyolysis in a patient with diabetes prepared for remnant ablation after thyroidectomy for differentiated thyroid carcinoma.MethodsWe performed a review of the Englishlanguage literature on the PubMed database using the terms hypothyroidism, muscle disease, hypothyroid myopathy, rhabdomyolysis, compression neuropathy, and acute compartment syndrome.ResultsMyopathy occurs frequently among patients with overt hypothyroidism; however, severe myoneural injury seems to be precipitated or accompanied by comorbid conditions. Focal peroneal neuropathy may be related to hypothyroidism-induced extrinsic compression from severe myopathy and soft tissue swelling in a narrowed fascial compartment.ConclusionSevere short-term iatrogenic hypothyroidism may lead to severe myopathy and compression nerve injury in patients with underlying diabetic neuropathy. We recommend avoidance of withdrawal of thyroid hormone for purposes of remnant ablation among patients with preexisting diabetic neuropathy. (Endocr Pract. 2011;17:629-635)     

Pericardial effusion due to hypothyroidism in Down syndrome: report of four cases

Pericardial effusion may be the first sign of congenital or acquired hypothyroidism and will completely resolve after thyroxin therapy. Hypothyroidism is more common in Down syndrome population than normal population. In this report we present four infants with Down syndrome who have pericardial effusion due to congenital hypothyroidism. All of these children with Down syndrome were admitted to our clinic with pericardial effusion. Pericardial effusion was completely resolved with thyroxin therapy without pericardiosentesis. Any child with Down syndrome who present with dyspnea and cardiomegaly should be suspected of having pericardial effusion due to hypothyroidism and echocardiography examination should be performed immediately. Pericardial effusion due to hypothyroidism will completely resolve with L-thyroxin therapy without pericardiosentesis. In conclusion, since a delayed diagnosis of hypothyroidism is likely and may favor the development of massive pericardial effusion and because of the difficult diagnosis of the hypothyroidism in Down syndrome, periodic follow-up of thyroid function tests are important.     

Cord transferrin and ferritin values for erythropoiesis in newborn infants of diabetic mothers

Neonatal polycythemia is a perinatal complication in infants of diabetic mothers. The cord CBC (complete blood counts), serum iron, transferrin and ferritin concentrations were studied in newborn infants of 9 GDM (gestational diabetes), 21 NIDDM (noninsulin-dependent diabetes mellitus), and 8 IDDM (insulin-dependent diabetes mellitus) mothers. The RBC (red blood cell) count, Hb (hemoglobin) and Hct (hematocrit) of these infants were higher than control infants. There was no difference between the serum iron concentration of the infants of each group diabetic mothers and the infants in the control group, but the transferrin concentration was significantly higher and the ferritin was significantly lower in the infants of diabetic mothers than in those of control mothers. There was a significant negative correlation between transferrin and ferritin (r = -0.491 p less than 0.001). Erythropoiesis is considered to be enhanced in the fetuses of diabetic mothers, and the iron needed for erythropoiesis is reportedly transported from the mother to the fetus according to the demands of the fetus, but the iron storage was shown to be reduced in the fetuses of diabetic mothers.     

Screening for congenital hypothyroidism in the Republic of Ireland.

A national pilot study for detecting congenital hypothyroidism by radioimmunoassay of thyroid-stimulating hormone concentrations in dried blood was incorporated into the newborn screening programme in Ireland on 1 August 1979. The programme has been monitored by a steering committee and follows the guidelines set by the European Society of Paediatric Endocrinologists. During the first 12 months 76 224 infants were screened and 19 cases confirmed, giving an incidence of 1:4012. Fifty infants (0.07%) were recalled for a serum sample, though most of the recalls (31; 0.04%) occurred during the first three months, before the methodology had become established. No case was detected clinically. At recall only three of the 19 affected infants had obvious features, and nine inconspicuous features. Organisation was directed at early diagnosis and treatment, the mean age at beginning treatment being 15 days. These results confirm the efficacy of screening for congenital hypothyroidism and suggest that capital and running costs will be offset by savings in maintenance treatment of untreated patients. Screening does not, however, remove the need for continued vigilance, and clinicians should request thyroid-function tests in any suspected case.     

Congenital hypothyroidism and pericardial effusion

A group of infants, affected by congenital hypothyroidism diagnosed through the neonatal screening program, was investigated with echocardiography to detect the presence of pericardial effusion. We studied the relationship between the effusion and the etiology of hypothyroidism, established through thyroid scintiscanning. Our data show a high prevalence of effusion in hypothyroid patients, without other clinical signs of cardiac involvement as well as a relationship between the etiology of hypothyroidism and the presence of effusion. This seems to be much more frequent in those forms which can imply a more severe hormonal defect, particularly during fetal life (agenesis/dyshormonogenesis). Furthermore, the high prevalence of pericardial effusion suggests to start the L-T4 replacement therapy with lower dosages as commonly advised, in order to avoid a cardiac involvement.     

Abnormalities in vascular arachidonic acid metabolism in the infant of the diabetic mother.

The infant of the diabetic mother has an increased incidence of thromboses in utero and in the neonatal period. In the adult with diabetes a decrease in prostacyclin formation has been suggested as a cause for the atherothrombotic tendency. We therefore evaluated arachidonic acid metabolism in infants of diabetic mothers. Endogenous radioimmunoassayable 6-keto prostaglandin F1 alpha (PGF1 alpha) was normal in umbilical vessels obtained from the infants of diabetic mothers whose glucose homoeostasis was maintained when compared with control values. Nevertheless, a significant inhibition of vascular production of 6-keto PGF1 alpha was observed in infants born to mothers with raised HbA1C concentrations. A decrease in the concentration of plasma 6-keto PGF1 alpha was also seen in the infants of diabetic mothers when compared with control neonates. The correlation observed between plasma 6-keto PGF1 alpha concentrations and endogenous vascular prostacyclin formation in the infants of diabetic mothers indicates that the in vitro deficiency of prostacyclin formation reflects a concomitant in vivo abnormality.     

Screening of newborn infants for galactosemia in British Columbia

With simple microbiologic and fluorescent tests, we detected two cases of classic galactosemia, confirmed by specific enzyme assays, in the first 25 000 newborn infants in British Columbia screened for this disorder. The results were equivocally abnormal for another 31 infants, and a second blood sample was requested from each, either for repeat screening or for enzyme assays. The two infants with galactosemia were in hospital with an undiagnosed acute illness and had only a trace of nonglucose reducing substances in the urine when the screening tests were done. Screening for galactosemia fits well with our established programs of screening for phenylketonuria and hypothyroidism and costs less than $1 per infant tested.     

Transient subclinical hypothyroidism in early pregnancy

In the present study, a new clinical state of transient subclinical hypothyroidism in 12 early pregnant women is documented. The incidence of transient subclinical hypothyroidism was 18 (0.19%) among 9,453 pregnant women examined in this series in Sapporo. The characteristics of transient subclinical early gestational hypothyroidism in our study may be summarized as follows: temporarily increased TSH in the blood (11.7 +/- 6.3 microU/ml; mean +/- S.D.) in early pregnant women at 8.5 +/- 2.4 weeks of gestation, accompanied with or without reduced FT4 which spontaneously return to normal at 17.9 +/- 7.1 weeks; no subjective complaints and no previous history of thyroid disease; small struma; positive titers of antimicrosome antibody and antithyroglobulin antibody; normal serum hCG; negative results for TSH receptor antibody. None of the infants show any physical abnormality such as struma and none of the patients had neck pain or fever suggesting subacute thyroiditis. The presence of autoantibody to the thyroid gland and echographical findings strongly suggest the existence of Hashimoto's thyroiditis in early pregnant women with transient subclinical hypothyroidism, although the cause of transient subclinical early gestational hypothyroidism remains obscure.     

Hypothyroidism Enhances Tumor Invasiveness and Metastasis Development

Background

Whereas there is increasing evidence that loss of expression and/or function of the thyroid hormone receptors (TRs) could result in a selective advantage for tumor development, the relationship between thyroid hormone levels and human cancer is a controversial issue. It has been reported that hypothyroidism might be a possible risk factor for liver and breast cancer in humans, but a lower incidence of breast carcinoma has been also reported in hypothyroid patients

Methodology/Principal Findings

In this work we have analyzed the influence of hypothyroidism on tumor progression and metastasis development using xenografts of parental and TRβ1–expressing human hepatocarcinoma (SK-hep1) and breast cancer cells (MDA-MB-468). In agreement with our previous observations tumor invasiveness and metastasis formation was strongly repressed when TRβ–expressing cells were injected into euthyroid nude mice. Whereas tumor growth was retarded when cells were inoculated into hypothyroid hosts, tumors had a more mesenchymal phenotype, were more invasive and metastatic growth was enhanced. Increased aggressiveness and tumor growth retardation was also observed with parental cells that do not express TRs.

Conclusions/Significance

These results show that changes in the stromal cells secondary to host hypothyroidism can modulate tumor progression and metastatic growth independently of the presence of TRs on the tumor cells. On the other hand, the finding that hypothyroidism can affect differentially tumor growth and invasiveness can contribute to the explanation of the confounding reports on the influence of thyroidal status in human cancer.     

Chronotropic function in spontaneously diabetic BB rats

In the present study, isolated atrial function in spontaneously diabetic BB Wistar rats maintained for 12 weeks on a low (BB-LI) and a high (BB-HI) dosage of insulin was examined. Basal atrial rates were unchanged in the diabetic animals, relative to nondiabetic littermates (ND-BB) or Wistar controls. The BB-HI animals were euglycemic and responded to isoproterenol in a similar manner to the ND-BB and Wistar control animals. In contrast, BB-LI animals remained hyperglycemic and exhibited lower responses to the maximum chronotropic effects of isoproterenol. Plasma thyroid hormone levels were unaltered in the BB-diabetic animals. These results therefore reveal an absence of bradycardia and hypothyroidism in spontaneously diabetic BB rats, in contrast to previous observations in streptozotocin diabetic rats. However, a decrease in chronotropic response to isoproterenol was still noted in the BB-LI animals. These findings suggest that decreased positive chronotropic effect of isoproterenol in diabetes may not be a direct consequence of altered thyroid status.     

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.     

Transient hypothyroidism in infants born to mothers with chronic thyroiditis--a nationwide study of twenty-three cases. The Transient Hypothyroidism Study Group

To define the difference in prognosis and the clinical features of transient neonatal hypothyroidism in infants born to mothers with chronic thyroiditis, we conducted a nationwide study of this condition. Sixteen mothers with chronic thyroiditis and twenty-three of their offspring with transient hypothyroidism were registered and reported in this paper. Five (group A) of twenty-two live infants showed physical, mental and/or psychomotor developmental delay (IQ below 80). No significant difference between TSH-binding inhibitor immunoglobulin (TBII) or thyroid-stimulation blocking antibody (TSBAb) activities in groups A and B (normal development) were noted. Moreover, there was no significant difference in thyroid function in the newborn period, ages at the start of thyroid medication or the dose and duration of treatment in the two groups. A striking difference observed between the two groups was the thyroid function of their mothers during pregnancy. In group A, four mothers were hypothyroid during pregnancy, and another mother discontinued thyroid medication in the last trimester and her baby was most delayed at the start thyroid medication. On the other hand, the mothers of only two of seventeen live cases in group B had mild hypothyroidism during pregnancy. There were two sets of siblings whose mother received inadequate treatment during the first pregnancy and adequate treatment during the second pregnancy. The psychomotor, physical and mental developmental delay were observed in their first babies. These findings suggested that maternal thyroid function during pregnancy might be an important factor in the prognosis of infants born to mothers with chronic thyroiditis.     

The prediction of thyroid function in infants born to mothers with chronic thyroiditis

To elucidate the relationship between the mother's TSH-receptor antibody activities and the status of thyroid dysfunction in their offspring, blood was taken from 5 mothers with chronic thyroiditis with potent thyrotropin (TSH)-receptor blocking activity, and the potency of TBII and TSBAb activity was assayed more quantitatively. In those mothers whose infants suffered from neonatal hypothyroidism, the 50% inhibition of binding of labeled TSH to its receptors was obtained at more than 30 to 50-fold dilution, while in those mothers whose infants had transiently increased TSH or were euthyroid, the titers were of less than 30-fold dilution. Similarly, in those mother whose infants suffered from neonatal hypothyroidism, the 50% inhibition of TSH-induced cAMP accumulation was obtained at approximately 400 to 3000-fold dilution, while in those mothers whose infants had transiently increased TSH or were euthyroid, the titers were of less than 50-fold dilution. On the other hand TBII activity was much less potent in serum from patients with Graves' disease. These results suggested that the titration of serum with dilution to obtain 50% inhibition of labelled TSH binding to its receptor may be the simplest way to predict thyroid dysfunction of the newborn infants born to mothers with chronic thyroiditis.     

Determination of total insulin (TIRI) in plasma of insulin-treated diabetics and newborn infants of insulin-treated diabetic mothers.

Plasma of insulin-treated diabetics and of newborn infants of insulin-treated diabetic mothers contains insulin antibodies which invalidates the radioimmunoassay of insulin. Therefore, the endogenous insulin antibody complex must be splitted at a pH lower than 5 and the total IRI (TIRI) is separated by ethanol extraction. It was investigated the recovery rate in dependence upon plasma volume used for extraction. By reduction of used plasma volume from 500 to 200 mul per extraction the recovery rate was increased from 65.1 +/- 8.4 to 88.3 +/- 4.2% (mean +/- SEM). The low plasma volume of 200 mul for TIRI extraction made it possible to determine TIRI during glucose loads of newborn infants. To eliminate different conditions of incubation for standard and unknown plasma samples the TIRI levels were computed by means of so-called "extracted" standard curve, obtained with extracted insulin from standard insulin dilution in insulin-free pooled human plasma. Using the described method a temporary regeneration of insulin secretion of a newly diagnosed juvenile diabetic after insulin treatment could be shown. In contrast to newborn infants of healthy mothers a biphasic/insulin release was found during the intravenous glucose loads in newborn infants of insulin-treated diabetic mothers.     

Suppression of TSH in congenital hypothyroidism is significantly related to serum levels and dosage of thyroxine

AIM: To assess thyrotropin (thyroid-stimulating hormone; TSH) suppression and serum thyroxine (T(4)) concentrations in infants with congenital hypothyroidism in relation to T(4) dose and pretreatment parameters. METHOD: A retrospective study of all cases treated in a single centre since neonatal screening began was performed. RESULTS: In 54 infants treated with a mean daily T(4) dose of 9.8 microg/kg, the TSH concentration was suppressed (<6 mU/l) in 65% of the cases by 6 months with the serum T(4) level at the upper end of the infant reference range. Infants who suppressed their TSH later did not differ in pretreatment serum TSH or T(4) concentration. T(4) dose and serum T(4) level were lower in infants whose TSH was not suppressed. CONCLUSIONS: TSH suppression in congenital hypothyroidism is significantly related to serum levels and dosage of T(4). We suggest that a delay in TSH suppression is mainly due to undertreatment.     

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.     

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