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

Mineralocorticoid receptor-associated hypertension and its organ damage: clinical relevance for resistant hypertension

The role of aldosterone in the pathogenesis of hypertension and cardiovascular diseases has been clearly shown in congestive heart failure and endocrine hypertension due to primary aldosteronism. In resistant hypertension, defined as a failure of concomitant use of three or more different classes of antihypertensive agents to control blood pressure (BP), add-on therapy with mineralocorticoid receptor (MR) antagonists is frequently effective, which we designate as "MR-associated hypertension". The MR-associated hypertension is classified into two subtypes, that with elevated plasma aldosterone levels and that with normal plasma aldosterone levels. The former subtype includes primary aldosteronism (PA), aldosterone-associated hypertension which exhibited elevated aldosterone-to-renin ratio and plasma aldosterone levels, but no PA, aldosterone breakthrough phenomenon elicited when angiotensin-converting enzyme inhibitor (ACE-I) or angiotensin II receptor blocker (ARB) is continued to be given, and obstructive sleep apnea. In contrast, the latter subtype includes obesity, diabetes mellitus, chronic kidney disease (CKD), and polycystic ovary syndrome (PCOS). The pathogenesis of MR-associated hypertension with normal plasma aldosterone levels is considered to be mediated by MR activation by pathways other than high aldosterone levels, such as increased MR levels, increased MR sensitivity, and MR overstimulation by other factors such as Rac1. For resistant hypertension with high plasma aldosterone levels, MR antagonist should be given as a first-line therapy, whereas for resistant hypertension with normal aldosterone levels, ARB or ACE-I should be given as a first-line therapy and MR antagonist would be given as an add-on agent.

Persistently raised thyroid stimulating hormone in adequately treated congenital hypothyroidism on long-term follow-up

AIM

To determine the percentage of patients with inappropriate secretion of TSH (ISTSH) in a large cohort of patients with congenital hypothyroidism (CH), and to examine a probable influence of the pretreatment T4 or TSH levels and the etiology of CH on ISTSH by describing the clinical features of these patients.

PATIENTS AND METHODS

We retrospectively examined the records, including anthropometric data, clinical findings, and thyroid function tests (TFT), of 500 children diagnosed with CH. Inclusion criteria of ISTSH were appropriate doses of L-T4, improvement of clinical findings, normalization of serum total T4 levels and persistently high TSH concentrations. A group of patients who demonstrated adequate suppression of TSH (<6 mU/l) with therapy among 500 CH patients were chosen randomly as a control group. Both groups were compared with regard to the etiology of CH, and TFT at baseline and during the treatment period.

RESULTS

Overall, 27 (5.4%) out of the 500 patients with CH had ISTSH. Nine patients (1.8%) with ISTHS did not show TSH normalization during the follow-up period. Four out of 27 patients with ISTSH had organic lesions (three empty sella, one corpus callosum agenesis) on cranial imaging. No statistically significant difference was found between the groups for etiological classification. The pretreatment T4 and TSH levels in ISTHS and control groups were not significantly different.

CONCLUSIONS

Our results suggest that a minority (5.4%) of adequately treated children with CH have persistently raised TSH levels. The delay in normalization of TSH is not related to pretreatment T4 and TSH values or the etiology of CH.

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.

Children with congenital hypothyroidism are at risk of adult obesity due to early adiposity rebound

OBJECTIVE

There is some evidence that children with congenital hypothyroidism (CH) are heavier than their reference population. There are few data on adults with CH. The timing of adiposity rebound (AR) in childhood has been shown to have strong correlations with adult obesity. Our aims were to study the timing of AR and factors affecting AR in children with CH.

PATIENTS AND METHODS

The timing of AR was examined in a retrospective study of children with CH with growth data at least up to 5 years of age. The proportion of children with CH who reached AR by 37 months and by 49 months of age were compared with healthy children and children with acute lymphoblastic leukaemia (ALL) described in the literature. Correlation of timing of AR with body mass index (BMI) standard deviation score (SDS) at 10 years, initial severity of hypothyroidism and age at normalization of TSH were examined. Multiple logistic regression was used to identify independent factors associated with BMI > or = 20 (overweight) at 10 years of age.

RESULTS

The study included 53 children (34 females and 19 males). AR had occurred by 37 months in 37.7% children with CH, in 42.7% children treated for ALL (CH vs. ALL, P = 0.58) and in 4.5% healthy British children (CH vs. normal, P < 0.0001). We found that 54.7% children with CH had reached AR compared with 21.4% of normal children (CH vs. normal, P < 0.0001) by the age of 49 months. Timing of AR showed significant negative correlation with BMI SDS at 10 years (r = -0.487, P = 0.01). There were no significant relationships between timing of AR and initial thyroid function or age at normalization of TSH. Multiple logistic regression analysis identified age at AR as an independent factor associated with BMI > or = 20 at 10 years of age (P = 0.04).

CONCLUSIONS

Children with CH showed significantly earlier AR compared to normal British children. This showed significant negative correlation with BMI SDS at 10 years. AR in CH does not appear to be directly related to the initial severity of hypothyroidism or to treatment factors.

Cognition and behavior at school entry in children with congenital hypothyroidism treated early with high-dose levothyroxine

OBJECTIVE

To document cognition and behavior at school entry in these patients. Study design Eighteen children with congenital hypothyroidism (CH; 9 severe and 9 moderate, based on a surface of the knee epiphyses at diagnosis<or >or=0.05 cm(2)) treated from a median of 14 days with a median of 12.0 microg/kg per day of levothyroxine were evaluated at 5 years, 9 months, with the McCarthy Scale and the Questionnaire for Evaluation of Social Behavior, as were 40 control children.

RESULTS

The global IQs at 5 years, 9 months, were similar: medians (range) were 102 (87 to 133), 102 (84 to 135), and 115 (88 to 136) (not significant) for severe CH, moderate CH, and control children, respectively. The behavioral scores of CH children were within the normal range. However, the number of times when plasma TSH was >6.0 mIU/L during treatment was correlated positively with anxiety (P=.02) and inattention (P=.05), whereas the number of times TSH was <0.8 mIU/L was correlated with lower verbal scores (P=.05).

CONCLUSIONS

Children with severe CH treated early with a high dose of levothyroxine have normal global development and behavior at school entry.