Effect Of L-thyroxine Treatment Research Articles

The effect of L-thyroxine treatment on ventricular dysfunction and pulmonary arterial stiffness in patients with subclinical hypothyroidism.

In our study, we aimed at evaluating the change in biventricular functions and pulmonary arterial stiffness (PAS) in patients with subclinical hypothyroidism (SH) in whom euthyroidism was achieved with L-thyroxine therapy. 70 SH patients and 75 healthy volunteers were included in our study consecutively. Baseline demographic and echocardiographic data of the participants were recorded. The data obtained in the control evaluation 6 months after the euthyroidism were achieved in the SH group patients started on L-thyroxine treatment and then compared with the baseline measurements. The mean age of patients in the SH group was 44.1 ± 9.4 years and 47.1% were women. Euthyroidism in SH patients was achieved with a mean daily L-thyroxine treatment of 59 µg/day for a mean of 16.1 ± 4.5 weeks. Positive changes in metabolic and hormonal profiles were achieved after L-thyroxine treatment in SH patients. It was determined that left ventricular and right ventricular isovolumetric relaxation and myocardial performance index were higher in SH patients compared to the control group, and these measurements were observed to decrease significantly with L-thyroxine treatment (p < 0.05 for each). While PAS was 16.9 ± 3.1 kHz/ms in the control group, it was 25.2 ± 5.3 kHz/ms in the SH group (p < 0.05). After L-thyroxine treatment, PAS measurements decreased to 17.2 ± 3.2 kHz/ms (p < 0.05) in the SH group and showed a positive change. Thyroid-stimulating hormone (TSH) change (Δ TSH) with Δ E/A ratio (r: -0.407, p < 0.001), right ventricular myocardial performance index (Δ RV MPI) change (r: 0.404, p < 0.001) and PAS change (Δ PAS) (r: 0.458, p < 0.001) found to be correlated. SH is associated with dysfunction in the biventricular and pulmonary vascular bed. Biventricular functions and PAS change positively in SH patients with L-thyroxine treatment.

The effect of l-thyroxine treatment on sexual function and depressive symptoms in men with autoimmune hypothyroidism.

Thyroid autoimmunity and mild hypothyroidism in women seem to be associated with sexual dysfunction and depressive symptoms. Data concerning similar associations in men are limited. The aim of this study was to investigate sexual functioning and depressive symptoms in men with autoimmune hypothyroidism. The study population consisted of three groups: men with autoimmune overt hypothyroidism (group A), men with autoimmune subclinical hypothyroidism (group B) and healthy euthyroid males without thyroid autoimmunity (group C). Apart from measuring serum levels of thyrotropin and free thyroid hormones and thyroid antibody titers, all included patients completed a questionnaires evaluating male sexual function (International Index of Erectile Function-15: IIEF-15) and assessing the presence and severity of depressive symptoms (Beck Depression Inventory-Second Edition - BDI-II) before and after 6 months of levothyroxine treatment. Men with overt hypothyroidism obtained lower scores in all five domains of IIEF-15, while men with subclinical hypothyroidism only in erectile function. The total BDI-II score was higher in groups A than in groups B and C, as well as higher in group B than in group C. L-thyroxine improved erectile function and normalized intercourse satisfaction, orgasmic function, sexual desire and overall satisfaction in group A, as well as normalized erectile function in group B. In group A, L-thyroxine reduced, while in group B tended to reduce total BDI-II. The obtained results suggest that autoimmune hypothyroidism in men is characterized by sexual and mood disturbances and that hypothyroid patients with sexual dysfunction and depressive symptoms benefit from L-thyroxine treatment.

Effects of L-thyroxine treatment on heart functions in infants with congenital hypothyroidism.

Impaired heart functions in newborns with hypothyroidism should be reversed by levothyroxine substitution therapy. The aim of the study was to investigate heart functions with congenital hypothroidism (CH) in newborns and changes after levothyroxine substitution therapy, measured with tissue Doppler echocardiography and conventional echocardiography. The study included 30 neonates with CH and 34 healthy controls. Echocardiography were performed at baseline, 2nd week and 6th month of therapy. Heart systolic function was normal. Mitral E velocities and mitral E/A ratios were significantly lower in patients at baseline. Tei indices were significantly higher in patients and a significant negative correlation was detected between free thyroxine levels and Tei indices.When early and late post-treatment echocardiography findings are compared, a non-significant difference was detected. Neonates with CH may exhibit systolic and diastolic heart dysfunction, which can be reversed by early L-T4 substitution treatment. The Tei index index should be measured in addition to conventional echocardiography.

IS SALUSIN-ALPHA A NEW MARKER OF CARDIOVASCULAR DISEASE RISK IN HYPOTHYROIDISM?

Salusins are multifunctional endogenous peptides shown in human and rat tissues. Serum salusin α level is decreased in coronary artery disease and lack of salusin α enhances coronary atherosclerosis. Hypothyroidism is a chronic inflammatory disease that has a high risk of developing cardiovascular disease. Here we aimed to search the relationship of overt hypothyroidism and subclinical hypothyroidism with salusin α and other inflammatory markers, also the effect of L-thyroxine treatment on these findings. 32 patients with overt hypothyroidism taking L-thyroxine treatment, 18 patients with subclinical hypothyroidism without treatment and 25 healthy patients as control group were included in the study. Serum salusin α, TNF α, sCRP, glucose, insulin and lipid levels were tested for all groups and results were evaluated with SPSS statistical analysis method. HDL, sCRP, salusin mean values were statistically significantly different in all 3 groups. HDL level was statistically significantly higher in control group compared to treatment group. sCRP level was higher and salusin level was lower in both treatment and non-treatment hypothyroidism groups compared to control group. When treatment and non-treatment hypothyroidism groups were compared, there was no statistically significant difference for salusin α, but HDL level was high and insulin level was low statistically significant in treatment group. Salusin α that is shown to be protective for coronary artery disease and hypertension, is found to be significantly low in hypothyroidism, thus it is a marker that increases the cardiovascular disease risk in this specific patient group.

Effects of L-thyroxine treatment on early markers of atherosclerotic disease in children with subclinical hypothyroidism.

To investigate the effect of levothyroxine (L-T4) treatment on early markers of atherosclerotic disease in children with mild idiopathic subclinical hypothyroidism (SH). Two-year, open, case-control prospective study. A total of 39 children, aged 9.18±3.56 years, with SH and 39 healthy controls were enrolled in the study. Waist-to-height ratio (WHtR), blood pressure, triglycerides, total cholesterol (total-C), HDL-C, LDL-C, non-HDL-C, triglycerides/HDL-C, atherogenic index (AI), homocysteine (Hcy), asymmetric dimethylarginine (ADMA), flow-mediated dilation (FMD) and intima-media thickness (IMT) were evaluated at baseline and after 2 years of L-T4 treatment in SH children and after 2 years of follow-up in controls. At study entry WHtR was higher in SH subjects compared with controls (0.56±0.08 vs 0.49±0.07, P=0.04) and significantly decreased after 2 years of treatment (0.50±0.06, P<0.0001). Mean HDL-C levels (50.47±11.43 vs 61.06±13.83mg/dL, P=0.002) were lower, while triglycerides/HDL-C (1.63±1.07 vs 1.19±0.69, P=0.05), AI (3.32±0.90 vs 2.78±0.68, P=0.005), and Hcy (9.35±2.61 vs 7.71±1.94μmol/L, P=0.01) were higher in SH subjects compared with controls and improved after 2 years of treatment (HDL-C 56.26±13.76mg/dL, P<0.0001; triglycerides/HDL-C 1.23±0.78, P=0.006; AI 2.82±0.68, P<0.0001; and Hcy 8.25±2.09μmol/L, P=0.06). ADMA concentrations at baseline were higher in SH subjects compared with controls (0.77±0.21 vs 0.60±0.16μmol/L, P=0.001) and decreased after therapy (0.58±0.13μmol/L, P<0.0001). FMD, IMT and other metabolic parameters were not different among SH subjects and controls at baseline and after 2 years. Children with SH may have subtle pro-atherogenic abnormalities. Although L-T4 treatment exerts some beneficial effects, the long-term impact of therapy on metabolic outcomes in SH children still remains unclear.

The effect of L-thyroxine treatment on hypothyroid symptom scores and lipid profile in children with subclinical hypothyroidism.

Objective: To evaluate i) the frequency of typical hypothyroidism symptoms in children with subclinical hypothyroidism (SH), ii) to evaluate the association of SH with lipoproteins and iii) to investigate possible improving effects of L-thyroxine (LT4) treatment on these findings.Methods: Twenty-seven children with SH who had elevated thyroid-stimulating hormone (TSH: >4.94 µIU/L) but normal free T4 levels and healthy euthyroid children of similar age and sex were enrolled in the study. Anthropometric and laboratory (lipid profile and thyroid function tests) measurements were performed at diagnosis and six months after euthyroidism was achieved. All children were also subjected to a questionnaire on hypothyroid symptoms at diagnosis. The SH patients were subjected to the questionnaire also following treatment. Pre-treatment data were compared with those of controls and post-treatment measurements.Results: Anthropometric and laboratory parameters of the groups were not statistically different except for higher TSH levels in the SH group. Serum lipoprotein levels and dyslipidemia frequency were similar between the groups. Compared to the controls, hypothyroidism symptom score was significantly higher in the SH group. Six months after euthyroidism was achieved, a significant reduction in the hypothyroid symptom score was obtained in the SH group. Except for significantly higher serum TSH values, no significant differences regarding demographic characteristics, symptom scores and lipid parameters were present between patients with Hashimoto’s thyroiditis and the remaining SH patients. Conclusion: The results of this study showed that in children with SH i) the hypothyroidism symptom score was significantly higher than in euthyroid children, ii) LT4 treatment improved the hypothyroidism symptom score and iii) SH does not seem to be associated with dyslipidemia.

The effect of L-thyroxine treatment on left ventricular functions in children with subclinical hypothyroidism

ObjectiveThe aim of this study was to search for evidence suggesting treatment for childhood subclinical hypothyroidism (SH) by evaluating left ventricular (LV) functions of children with SH by using M-mode...

Echocardiographic Evaluation of Diastolic Dysfunction in Patients with Subclinical Hypothyroidism &amp; the effect of L-Thyroxine treatment: A hospital based study

Background &amp; Aims: Diastolic dysfunction is the common condition with Subclinical Hypothyroidism and is reversible in many cases after treatment. We aimed to investigate the response of diastolic dysfunction to thyroid hormone replacement therapy in patients of Subclinical Hypothyroidism. Methods: Forty newly diagnosed cases of Subclinical Hypothyroidism (38 females and 2 males) and age more than 18 years were included. Diagnosis was made on the basis of history, clinical examination and thyroid function tests. Echocardiography was performed in all and was repeated after 4-6 months in those who had diastolic dysfunction. Distribution of Diastolic dysfunction among the involved cases and their response to treatment with L-thyroxine were studied. Results: The diastolic dysfunction was found in 15 (37.5%) and pericardial effusion (PE) in five (12.5%) patients. Fourteen of them had impaired relaxation abnormality and only one patient had pseudonormal pattern. With replacement therapy, 13 reverted back to the normal whereas one having grade 2 diastolic dysfunction (pseudonormal pattern) reverted to grade 1. One patient who had grade 1 diastolic dysfunction (impaired relaxation) did not improve. Pericardial effusion subsided in all 5 cases. Conclusions: Echocardiography may be a useful tool for monitoring the response of diastolic dysfunction to thyroid hormone replacement therapy in patients with Subclinical Hypothyroidism. Our findings suggest that Thyroid Hormone Replacement Therapy may reverse diastolic dysfunction in Subclinical Hypothyroidism. DOI: http://dx.doi.org/10.3126/njh.v11i1.10979 Nepalese Heart Journal 2014;11(1): 33-38

Serum resistin and high sensitive CRP levels in patients with subclinical hypothyroidism before and after L-thyroxine therapy

BackgroundSubclinical hypothyroidism (SH) is defined by increased thyrotropin (TSH) and normal free thyroxine (fT4) and free triiodothyronine (fT3) levels. Resistin is secreted from adipose tissue and is reported to be associated with insulin resistance and/or inflammation. High sensitive CRP (hs-CRP) is a reliable marker of inflammation. Data related to levels of resistin and hs-CRP in SH and the effect of L-thyroxine treatment on those is limited. We aimed to determine the levels of resistin and hs-CRP in women with SH, and potential effects of L-thyroxine therapy on those levels.Material/MethodsThirty-six patients with SH and 27 age- and BMI-matched healthy control women were included. Waist circumference (Wc), waist-to-hip ratio (WHR), resting energy expenditure (REE), fat mass (FM) and lean mass (LM), TSH, free T4 (fT4), free T3 (fT3), total cholesterol (TC), triglycerides (TG), and HDL- and LDL-cholesterol were determined in all participants. Patients received L-thyroxine treatment for 6 months, after which all measurements were repeated. Resistin and hs-CRP levels were studied from frozen samples after the completion of the study.ResultsThe 2 groups had similar values for Wc, WHR, FM, LM, TC, TG, HDL-C, LDL-C, resistin, and hs-CRP at the beginning. fT4 were higher, whereas TSH was lower in the control group. Resistin and hs-CRP levels did not change after treatment. hs-CRP correlated with BMI and FM before and after treatment.ConclusionsOur results suggest that achievement of euthyroid status by replacement therapy did not change resistin or hs-CRP levels in women with SH. hs-CRP correlated with parameters of obesity, which emphasizes the role of body weight in inflammation.

The Evaluation of Diastolic Dysfunction with Tissue Doppler Echocardiography in Women with Subclinical Hypothyroidism and the Effect of L-Thyroxine Treatment on Diastolic Dysfunction: A Pilot Study

Background. Subclinical hypothyroidism (SH) predominantly affects women. The necessity of treatment in SH is controversial. Objective. We aimed to investigate the response of diastolic dysfunction to thyroid hormone replacement therapy (THRT) in women. Methods and Results. Twenty-two female subjects with SH and 20 euthyroid female controls were enrolled. Baseline and follow-up biochemical, hormonal, and echocardiographic evaluations were performed. Repeat echocardiograms were performed three months after the achievement of a euthyroid status with THRT. Mean baseline myocardial performance index (MPI) was 0.27 ± 0.08 in the SH group, and 0.22 ± 0.06 in the control group (P = 0.03). MPI did not change significantly after THRT. Pulsed-wave Doppler findings were not different among the groups. However, tissue Doppler-derived mitral annular E' velocities were significantly lower in the SH group. A moderate but significant improvement was observed in E' velocities after THRT (13.2 ± 3.87 versus 14.53 ± 2.75, P = 0.04). We also observed left ventricular concentric remodeling in SH patients which was reversible with THRT. Conclusions. Tissue Doppler echocardiography may be a useful tool for monitoring the response of diastolic dysfunction to thyroid hormone replacement therapy in patients with SH. Our findings suggest that THRT may reverse diastolic dysfunction in women with SH.

Influences of hypertonic and hypovolemic treatments on vasopressin response in propylthiouracil (PTU) induced hypothyroid rat and effect on supplementation with L-thyroxine

This study was performed to investigate the effects of L-thyroxine treatment on plasma vasopressin (AVP) levels in rats with hypothyroidism induced by propylthiouracil (PTU). Animals were separated into three groups each having 6 rats: control, PTU, PTU+L-thyroxine groups. Then, the groups were further divided into 3 sub-groups including 6 rats (a; basal, b; hypertonic stimulated and c; hypovolemic stimulated). At the end of the experiments all rats were decapitated in order to obtain plasma samples for analysis in terms of Hct, osmolality, TT 3 , TT 4 and vasopressin. Haematocrit (Hct) levels were the highest in hypovolemic stimulated sub-group (P < 0.001). Osmolality levels were higher in hypertonic stimulated sub-groups (P < 0.001). Total T 3 and T 4 values were the lowest in the PTU group and the highest in the L-thyroxine treated group (P < 0.001). Plasma AVP levels were reduced by hypothyroidism. However, L-thyroxine treatment after the hypothyroidism prevented this reduction (P < 0.001). Vasopressin responses to basal, hypovolemic and hypertonic stimulations were the lowest in the PTU group (P < 0.001). The results of the present study show that basal and stimulated plasma vasopressin levels are reduced in PTU-induced hypothyroidism. However, L-thyroxine treatment following hypothyroidism prevents this reduction.

The Effects of L-thyroxine Treatment on QT Dispersion in Primary Hypothyroidism

Hypothyroidism has various cardiovascular manifestation and exhibits electrocardiographic change. The QT dispersion on surface ECG reflects regional variations in myocardial repolarization. The effect of L-thyroxine treatment on ECG parameters, such as QT dispersion, in patients with primary hypothyroidism were investigated. This study involved 18 patients (3 men, 15 women, ages: 48±18 yr) with primary hypothyroidism. All patients were checked with a standard 12-lead ECG before and after L-thyroxine treatment. Various ECG parameters were then measured twice. The mean L-thyroxine treatment duration was 22±2.7 months. The mean thyroid-stimulating hormone levels of patients before and after therapy were 40.2±29.8 µU/mL, 3.6±4.6 µU/mL (p<0.001) and free-T4 levels were 0.44±0.38 ng/dL, 1.51±0.39 ng/dL (p<0.001). After L-thyroxine treatment, QT interval (395±42 vs. 380±24 msec, p<0.05), QTc interval (434±32 vs. 417±23 msec, p<0.05), QT dispersion (45±23 vs. 30±13 msec, p=0.008), QTc dispersion (49±23 vs. 32±14 msec, p=0.005) significantly decreased. There were no significant changes in the PR and RR intervals, as well as the QRS duration. Our findings suggest that the thyroid hormone affects ventricular inhomogenicity, and that L-thyroxine replacement therapy may reduce malignant ventricular arrhythmia and sudden cardiac death in primary hypothyroidism.

The effect of l-thyroxine treatment on skin accumulation of acid glycosaminoglycans in primary myxoedema.

We assessed skin accumulation of acid glycosaminoglycans in ten patients with primary myxoedema (median age 70 years) before and during l-thyroxine treatment (median 7 months). Eight subjects matched for sex and age served as controls. Acid glycosaminoglycans were determined biochemically on small skin biopsies. Hyaluronic acid was elevated in untreated myxoedema, median 0.60, range 0.39-0.90 microgram hexosamine/mg dried defatted tissue compared to a median control value of 0.52, range 0.43-0.65 microgram hexosamine/mg dried defatted tissue, P less than 0.02. Chondroitin-4,6-sulphate and dermatan sulphate showed no elevation, while heparan sulphate was actually reduced in myxoedema, P less than 0.01. l-thyroxine treatment induced a significant reduction in hyaluronic acid, median 0.41, range 0.24-0.71 microgram hexosamine/mg dried defatted tissue, while no consistent changes occurred in the remaining three acid glycosamine glycans. The accumulation of hyaluronic acid might contribute to the peculiar non-pitting oedema of the skin in myxoedema, due to the strong water-binding capacity of the substance.

Effects of L-thyroxine treatment on pituitary GH content of adult rats with neonatal thyrotoxicosis.

Rats receiving large doses of thyroxine (30 micrograms/5 doses) during their first days of life develop an apparently permanent alteration of the hypothalamus-pituitary-thyroid complex. This neonatal thyrotoxicosis has been called neo-T4 syndrome. A state of permanent but not very severe hypothyroidism seems to be induced, accompanied by a decrease in pituitary GH content at least until day 22. In this work, growth hormone content has been measured by a specific radioimmunoassay in the anterior pituitary of 45 and 78 day old neo-T4 and control (saline-injected) rats. GH content of the adult neo-T4 treated animals was significantly lower than that of the adult controls. Administration of different doses of T4 (1.7 micrograms/100 g body weight/3 doses or 2.5 micrograms/100 g body weight/8 doses, to 70 day old rats, and 5 micrograms/100 g body weight/3 doses to 42 day old rats) to adult neo-T4 rats did not alter these decreased pituitary GH levels. This differs from hypothyroid rats, in which T4 administration has been shown to increase pituitary GH content. A third approach was to thyroidectomize neo-T4 and control rats and administer 5 micrograms T4/100 g body weight, which produced the same increase in pituitary GH in both groups of animals. These results seem to indicate that changes in pituitary GH content of neo-T4 rats are not due to hypothyroidism. Thus, it would appear that treatment with large T4 doses during the early perinatal period not only deranges the hypothalamic-pituitary-thyroid axis but other pituitary functions as well.

The effect of L-thyroxine treatment on the metabolism of tritium-labelled catecholamines in the rat.

The effect of L-thyroxine treatment on the metabolism of tritium-labelled catecholamines in the rat.