Diagnostic strategies for subclinical hypothyroidism

The Association Between Anti-Thyroid Peroxidase Antibody and Dyslipidemia in Subclinical Hypothyroidism Among the Rural Population of Central India

Objective

In this study, we aimed to determine the association between anti-thyroid peroxidase (anti-TPO) antibody and dyslipidemia in subclinical hypothyroidism (SCH).

Materials and methods

We conducted a cross-sectional case-control study in the department of medicine at a tertiary care teaching hospital in central India. The study consisted of 150 patients (75 cases and 75 controls) who fulfilled the inclusion and exclusion criteria.

Results

The study showed that serum cholesterol was high in 23.1% of cases in the negative anti-TPO antibody SCH sub-group and 88.7% of cases in the positive anti-TPO antibody SCH sub-group (p<0.001). Serum triglyceride (TG) levels were high in 61.5% of cases in the negative anti-TPO antibody SCH sub-group and 90.3% of cases in the positive anti-TPO antibody SCH sub-group (p=0.008). Serum high-density lipoproteins (HDL) were low in 15.4% of cases in the negative anti-TPO antibody SCH sub-group and 24.2% of cases in the positive anti-TPO antibody SCH sub-group (p=0.490). Serum low-density lipoproteins (LDL) were high in 61.5% of cases in the negative anti-TPO antibody SCH sub-group and 90.3% of cases in the positive anti-TPO antibody SCH sub-group (p=0.008). Serum very-low-density lipoproteins (VLDL) were high in 84.6% of cases in the negative anti-TPO antibody SCH sub-group and 83.9% of cases in the positive anti-TPO antibody SCH sub-group (p=0.947). Based on our findings, 82.8% of participants with negative anti-TPO antibodies had normal serum LDL levels, while 11.1% of participants with positive anti-TPO antibodies had normal LDL levels (p<0.001). The study also showed that elevated serum LDL was present in 17.2% of participants with negative anti-TPO antibody levels and 88.9% of participants with positive anti-TPO antibodies (p<0.001). The study showed a correlation coefficient of 0.0432 between serum TG and anti-TPO antibody levels (p<0.001).

Conclusion

Our findings showed an increased incidence of dyslipidemia in SCH patients with positive anti-TPO antibodies. SCH with positive anti-TPO antibody is significantly associated with elevated serum total cholesterol (TC) levels, serum TG levels, and serum LDL levels. Hence, early screening and diagnosis of dyslipidemia are crucial to prevent cardiovascular morbidity and mortality in SCH patients with positive anti-TPO antibodies.

HbA1c is inversely associated with thyroid cysts in a euthyroid population: A cross-sectional study

Anti-thyroid peroxidase antibody (TPO-Ab) is revealed to be inversely associated with thyroid cysts among euthyroid population. TPO-Ab causes autoimmune thyroiditis by bolstering thyroid inflammation. Therefore, at least partly, absence of thyroid cysts could indicate latent thyroid damage. Since participants with subclinical hypothyroidism are reported to have higher HbA1c than normal healthy controls, HbA1c could be inversely associated with thyroid cysts through a mechanism reflecting latent thyroid damage. To investigate the association between HbA1c and thyroid cysts among a euthyroid population, a cross-sectional study was conducted on 1,724 Japanese individuals who were within the normal range of thyroid function [i.e., normal range of free triiodothyronine (T3) and free thyroxine (T4)] and aged 40–74 years. Among this study population, 564 were diagnosed with thyroid cysts. Independently of thyroid related hormones [thyroid stimulating hormone (TSH), free T3, and free T4] and known cardiovascular risk factors, HbA1c was found to be significantly inversely associated with the presence of thyroid cysts. This association remained significant even after this analysis was limited to participants within a normal range of TSH. The fully adjusted odds ratios (ORs) of thyroid cysts for 1 standard deviation (SD) increment of HbA1c were 0.84 (0.74, 0.95) for total participants and 0.80 (0.70, 0.92) for participants within a normal range of TSH. Among participants with normal thyroid function, HbA1c was inversely associated with the presence of thyroid cysts. The absence of thyroid cysts and higher levels of HbA1c could indicate the latent functional damage of the thyroid.

Anti-thyroid peroxidase antibody and subclinical hypothyroidism in relation to hypertension and thyroid cysts

Hypertension frequently occurs in subclinical hypothyroidism (SCH). By bolstering thyroid inflammation, anti-peroxidase antibody (TPO-Ab) causes autoimmune thyroiditis, which is one of the most common causes of SCH. Since the absence of thyroid cysts is associated with TPO-Ab (+) based on the indication of latent thyroid damage, we explored the potential mechanism underlying the association among TPO-Ab, SCH, hypertension, and thyroid cysts. A cross-sectional study of 1,483 Japanese aged 40–74 years was conducted. Thyroid cysts were defined as those having a maximum diameter of ≥ 2.0 mm, containing no solid component. TPO-Ab (+) was positively associated with SCH with hypertension (adjusted odds ratio [OR] and 95% confidence interval [CI], 2.62 [1.40, 4.89]) but not with SCH without hypertension (0.84 [0.37, 1.89]), respectively. Moreover, among participants without thyroid cysts, SCH was positively associated with hypertension (2.15 [1.23, 3.76]) but not among participants with thyroid cysts (0.58 [0.16, 2.16]), respectively. TPO-Ab was positively associated with SCH with hypertension, but not with SCH without hypertension. In addition, status of thyroid cysts might act as a determinant factor on the association between SCH and hypertension. These findings are efficient tools to clarify the background mechanism that underlies SCH.

High Thyroid-stimulating Hormone Level in Down's Syndrome: A Mere Resetting of Hypothalamopituitary Axis in Subclinical Hypothyroidism?

OBJECTIVE

Hyperthyrotropinemia (HT) or reduced thyroid function in Down syndrome (DS) is not uncommon, causes range from glandular dysgenesis to altered hypothalamopituitary axis. In the present study, we have compared hypothyroid Indian children with and without DS (NDS), especially focusing on family history, goiter, and biochemical features.

METHODS

We conducted this retrospective observational study from previous medical records of children with DS (1-17 years) having an elevated TSH (≥5 mIU/L) who were consecutively referred for with HT to Endocrinology OPD of a tertiary care hospital in India. Records from hypothyroid children (1-17 years) without Down Syndrome (NDS) were evaluated as controls. Free thyroxine (FT4), anti-thyroid peroxidase (TPO) antibody were measured and congenital hypothyroidism was excluded in all subjects.

RESULTS

Thirty-four DS cases [median age 8 years (IQR: 2-14), M: F = 13:21] and 34 controls [median age 10.5 years (IQR: 7-13.25), M: F = 13:21] were comparable in terms of age and sex, Median age of presentation was significantly earlier in case of DS vs NDS [7 years vs. 10 years]. DS children had significantly less family history of thyroid disorders compared to NDS [14.7% vs 64.7%]. Goiter was significantly less common in patients with DS [DS - 32.25% vs. NDS - 73.5%, P = 0.001]. Anti-TPO antibody positivity was significantly less common in patients with DS [DS- 41% vs. NDS- 73.5%, P = 0.014].

CONCLUSION

There is a significant difference in presentation in hypothyroid children with DS compared to NDS. DS children with hypothyroidism compared to NDS, had earlier presentation, lower incidence of traceable family history, goiter, and anti-TPO-antibody positivity.

Subclinical Hypothyroidism and Associated Cardiovascular Risk Factor in Perimenopausal Females

Background

Perimenopause refers to the period around menopause (40-55 years). This includes the period before menopause and the first year after menopause. Perimenopausal age is an important stage in a women's life. Many women are diagnosed with hypothyroidism at midlife. Hypothyroidism - both overt and subclinical are associated with increased risk of CVS diseases. Subclinical hypothyroidism is more important as this stage is usually ignored from treatment point of view and if early intervention is done in SCH worsening of metabolic derangement may be avoided.

Objectives

The present study was aimed to know the prevalence of subclinical hypothyroidism and associated dyslipidemia in perimenopausal females.

Material and Methods

In our retrospective study we took 100 perimenopausal females (40-55years) who were investigated for thyroid and lipid profile. Atherogenic indices like TC/HDL-c, LDL-c/HDL-c, TG/HDL-c ratios were calculated from the individual lipid profile parameters. The reference guidelines for lipid profile was according to NCEP ATP III.

Result

Subclinical hypothyroidism was found to be present in 18% of perimenopausal females The mean TSH levels were found to be higher in SCH as compared to euthyroid females with a mean value of 7.56±3.54(μIU/ ml). Dyslipidemia was seen in patients with SCH. TSH levels were found to be positively correlated with total cholesterol.

Conclusion

We conclude that subclinical hypothyroidism is present in 18% females of perimenopausal age group. Increased TSH levels are associated with hypertension, hypertriglyceridemia, and elevated TC/HDL-C ratio and non cholesterol HDL. In perimenopausal women the condition is usually underdiagnosed and ignored but subclinical hypothyroidism in these females should be screened and treated timely to decrease the risk of accelerated atherosclerosis and premature coronary artery disease in them.

Assessment of subclinical hypothyroidism for a clinical score and thyroid peroxidase antibody: a comparison with euthyroidism grouped by different thyroid-stimulating hormone levels

Background

Subclinical hypothyroidism (SCH) might have many symptoms of hypothyroidism. The controversy appears to lower the level of thyroid-stimulating hormone (TSH) and group subjects with TSH of more than 3 or even 2.5 mIU/L as SCH subjects.

Objectives

To assess SCH subjects both clinically using Zulewski clinical score and biochemically and to evaluate whether the euthyroid subjects with high-normal TSH (HNT) have any clinical symptom or subnormal biochemical finding.

Methods

A prospective cross-sectional study of 233 subjects, 67 with SCH and 166 euthyroidism, was conducted. Euthyroid subjects were divided according to the level of TSH as HNT (>2.5 mIU/L) and low-normal TSH (0.5–2.5 mIU/L). The subjects were examined for clinical feature including Zulewski clinical score and biochemical evaluations including thyroid peroxidase antibody (TPO-Ab) titer. The comparisons between groups were assessed using independent sample t test, and correlations between variables were evaluated using Pearson correlation.

Results

A significantly higher clinical score and higher frequencies of symptoms were found in the SCH group compared to the euthyroid group. The most frequent symptom was fatigue. Euthyroid subjects with HNT were found to have higher TPO-Ab titers than those with low-normal TSH, P < 0.05. The Zulewski clinical score was positively correlated with TSH and TPO-Ab titer but negatively correlated with the FT4 level, P < 0.05.

Conclusions

Zulewski clinical score is higher in SCH subjects compared to euthyroid subjects and can aid in assessing SCH subjects. A significant correlation exists between Zulewski clinical score and each of the TSH, FT4, and TPO-Ab titer levels. The frequency of TPO-Ab positivity is high in SCH. Additionally, euthyroid with higher TSH levels has higher level of TPO-Ab titer but not higher clinical score.

Association of thyroid peroxidase antibody and dyslipidemia in subclinical hypothyroidism

Context:

Subclinical hypothyroidism (SCH) is stated as mild thyroid failure, is more common as compared to overt hypothyroidism, is associated with different biochemical abnormalities such as dyslipidemia, and is also having high conversion rate into overt hypothyroidism in patients having thyroid peroxidase (TPO) antibody positive. Lipid abnormalities are controversial in SCH and there is lack of Indian studies showing correlation between lipid abnormalities and TPO positivity in SCH. Hence, we did this study to find the TPO positivity and associated dyslipidemia in SCH patients.

Materials and Methods:

It was a prospective observational study from January 2015 to December 2015 including fifty adult diagnosed SCH patients presented in outpatient department of Sri Balaji Action Medical Institute, Paschim Vihar, New Delhi. TPO positivity and different lipid abnormalities were studied in those fifty diagnosed SCH patients, and finally, association between TPO antibody and dyslipidemia was calculated.

Results:

Females were predominant (86%). TPO was positive in 56% SCH patients. Dyslipidemia was found in 100% of SCH patients with positive TPO antibody. In overall, TPO positive patients as well as TPO positive females, total cholesterol, triglyceride, and low-density lipoprotein were significantly high while high-density lipoprotein was insignificant. In males, no significant association was found.

Conclusion:

In SCH patients, dyslipidemia is significantly associated with TPO positivity, especially in females. Hence, early screening, diagnosis, and treatment of SCH patients are recommended to prevent further risks.

Coronary artery calcium scoring is a better predictor of cardiac risk in subclinical hypothyroidism patients with low-risk Framingham score

CONTEXT

Overt hypothyroidism accelerates the cardiovascular disease. Subclinical hypothyroidism (SCH), being considered as a preclinical state, impacts on cardiovascular status is not clear.

AIMS

This study was aimed at assessing cardiac risk stratification by Framingham risk scoring (FRS) and coronary coronary artery calcium score (CACS) by noncontrast cardiac computed tomography in SCH.

STUDY DESIGN

Observational study.

SUBJECTS AND METHODS

We enrolled thirty treatment-naive SCH patients (aged 30-60 years with no serious concurrent medical conditions), thirty euthyroid (age, sex, and body mass index-matched) controls, and ten healthy controls. All cases were evaluated for coronary artery calcium scoring and Framingham risk score.

STATISTICAL ANALYSIS

Qualitative data were analyzed using the Chi-square test. In addition, demographics and CACS are summarized graphically or in a table.

RESULTS

SCH cases had higher thyroglobulin, while there was a trend toward an increase in total cholesterol, low-density lipoprotein (LDL), very LDL, and decrease in HDL levels. All participants had low-risk FRS (10-year FRS < 10%). The mean CACS in SCH was significantly higher than simple obese and healthy controls (47.17 vs. 2.67 vs. 0.00).

CONCLUSION

This study suggests that SCH is an independent risk factor for coronary artery disease in apparently healthy controls. The risk of occult coronary artery disease is increased in SCH cases.

Are we using Thyroid Function Tests Appropriately?

Thyroid function tests are very important for the diagnosis and monitoring of patients with thyroid dysfunction. The guidelines recommend serum thyroid stimulating hormone (TSH) as the single most reliable test to diagnose all common forms of hypothyroidism and hyperthyroidism. The aim of this study was to analyze the ordering pattern for thyroid function tests by physicians and the analysis of results based on the clinical history. The mean age of the patients was 32.5 ± 6.5 years. Majority of samples (87.7% of total) were received from the departments of Medicine and Gynae. Thyroid profiles (47.5%) were ordered more frequently as compared to TSH only (46%). There was no significant difference in the percentage of normal reports for both types of tests. 77.8% of TFT and 76.6% of TSH samples had results within the reference range. The percentage of abnormal results was 13.7% in the patients who were screened for thyroid disorders. There is a need to redefine the case definition for thyroid dysfunction and order the appropriate test in a rational and cost effective manner.

Serum anti - TPO levels in benign and malignant breast tumors

Breast cancer is a hormone dependent neoplasm. Conflicting results regarding the clinical correlation between breast cancer and thyroid diseases have been reported. The objective of this study was to determine the association of anti - TPO levels in patients having complaints of a lump in breast. Serum samples and Fine needle aspiration cytology (FNAC) samples were collected from 31 female patients with a lump in breast between the age group of 20-75 years. 31 age matched normal healthy controls were also examined for the same parameters. Serum samples were analyzed for its anti - TPO levels. FNAC reports confirmed patients as having duct cell carcinoma. They had raised serum anti - TPO levels compared to controls. FNAC results of others (n=26) were reported as fibroadenoma whose anti - TPO levels were less than the controls.