Summary Hypothyroidism is a common condition of thyroid hormone deficiency, which is readily diagnosed and managed but potentially fatal in severe cases if untreated. The definition of hypothyroidism ...is based on statistical reference ranges of the relevant biochemical parameters and is increasingly a matter of debate. Clinical manifestations of hypothyroidism range from life threatening to no signs or symptoms. The most common symptoms in adults are fatigue, lethargy, cold intolerance, weight gain, constipation, change in voice, and dry skin, but clinical presentation can differ with age and sex, among other factors. The standard treatment is thyroid hormone replacement therapy with levothyroxine. However, a substantial proportion of patients who reach biochemical treatment targets have persistent complaints. In this Seminar, we discuss the epidemiology, causes, and symptoms of hypothyroidism; summarise evidence on diagnosis, long-term risk, treatment, and management; and highlight future directions for research.
Context:
Although thyroid function is associated with several risk factors of nonalcoholic fatty liver disease (NAFLD), its role in NAFLD development remains unclear.
Objective:
We aimed to ...prospectively investigate the association between variations in thyroid function and NAFLD.
Design and Setting:
The Rotterdam Study, a large population-based, prospective cohort study.
Participants and Main Outcome Measures:
Participants with thyroid function measurements at baseline and NAFLD data (ie, at baseline fatty liver index/at follow-up ultrasound) were eligible. Transient elastography was performed to assess the presence of fibrosis in patients with NAFLD, using the liver stiffness measurements more than or equal to 8 kPa as cutoff for clinically relevant fibrosis. The association between thyroid parameters and incident NAFLD was explored by using logistic regression models.
Results:
A total of 9419 participants (mean age, 64.75 y) were included. The median follow-up time was 10.04 years (interquartile range, 5.70–10.88 y). After adjusting for age, sex, cohort, follow-up time, use of hypolipidemic drugs, and cardiovascular risk factors, higher free T4 levels were associated with a decreased risk of NAFLD (odds ratio, 0.42; 95% confidence interval CI, 0.28–0.63). In line, higher TSH levels were associated with an increased risk of having clinically relevant fibrosis in NAFLD (odds ratio, 1.49; CI, 1.04–2.15). Compared with euthyroidism, hypothyroidism was associated with a 1.24-fold higher NAFLD risk (CI, 1.01–1.53). Moreover, NAFLD risk decreased gradually from hypothyroidism to hyperthyroidism (P for trend = .003).
Conclusion:
Lower thyroid function is associated with an increased NAFLD risk. These findings may lead to new avenues regarding NAFLD prevention and treatment.
This study evaluated the effect of thyroid function on the subsequent risk of NAFLD and presence of clinically relevant fibrosis. Lower thyroid function was associated with an increased NAFLD risk.
The impact of non-communicable diseases (NCDs) in populations extends beyond ill-health and mortality with large financial consequences. To systematically review and meta-analyze studies evaluating ...the impact of NCDs (including coronary heart disease, stroke, type 2 diabetes mellitus, cancer (lung, colon, cervical and breast), chronic obstructive pulmonary disease and chronic kidney disease) at the macro-economic level: healthcare spending and national income. Medical databases (Mediine, Embase and Google Scholar) up to November 6th 2014. For further identification of suitable studies, we searched reference lists of included studies and contacted experts in the field. We included randomized controlled trials, systematic reviews, cohorts, case-control, crosssectional, modeling and ecological studies carried out in adults assessing the economic consequences of NCDs on healthcare spending and national income without language restrictions. All abstracts and full text selection was done by two independent reviewers. Any disagreements were resolved through consensus or consultation of a third reviewer. Data were extracted by two independent reviewers using a pre-designed data collection form. Studies evaluating the impact of at least one of the selected NCDs on at least one of the following outcome measures: healthcare expenditure, national income, hospital spending, gross domestic product (GDP), gross national product, net national income, adjusted national income, total costs, direct costs, indirect costs, inpatient costs, outpatient costs, per capita healthcare spending, aggregate economic outcome, capital loss in production levels in a country, economic growth, GDP per capita (per capita income), percentage change in GDP, intensive growth, extensive growth, employment, direct governmental expenditure and non-governmental expenditure. From 4,364 references, 153 studies met our inclusion criteria. Most of the studies were focused on healthcare related costs of NCDs. 30 studies reported the economic impact of NCDs on healthcare budgets and 13 on national income. Healthcare expenditure for cardiovascular disease (12-16.5 %) was the highest; other NCDs ranged between 0.7 and 7.4 %. NCD-related healt costs vary across the countries, regions, and according to type of NCD. Additionally, there is an increase in costs with increased severity and years lived with the disease. Low- and middle-income (LMI) countries were the focus of just 16 papers, which suggests an information shortage concerning the true economic burden of NCDs in these countries. NCDs pose a significant financial burden on healthcare budgets and nations' welfare, which is likely to increase over time. However further work is required to standardize more consistently the methods available to assess the economic impact of NCDs and to involve (hitherto under-addressed) LMI populations across the globe.
The association of thyroid function with risk of type 2 diabetes remains elusive. We aimed to investigate the association of thyroid function with incident diabetes and progression from prediabetes ...to diabetes in a population-based prospective cohort study.
We included 8452 participants (mean age 65 years) with thyroid function measurement, defined by thyroid-stimulating hormone (TSH) and free thyroxine (FT4), and longitudinal assessment of diabetes incidence. Cox-models were used to investigate the association of TSH and FT4 with diabetes and progression from prediabetes to diabetes. Multivariable models were adjusted for age, sex, high-density lipoprotein cholesterol, and glucose at baseline, amongst others.
During a mean follow-up of 7.9 years, 798 diabetes cases occurred. Higher TSH levels were associated with a higher diabetes risk (hazard ratio HR 1.13; 95 % confidence interval CI, 1.08-1.18, per logTSH), even within the reference range of thyroid function (HR 1.24; 95 % CI, 1.06-1.45). Higher FT4 levels were associated with a lower diabetes risk amongst all participants (HR 0.96; 95 % CI, 0.93-0.99, per 1 pmol/L) and in participants within the reference range of thyroid function (HR 0.96; 95 % CI, 0.92-0.99). The risk of progression from prediabetes to diabetes was higher with low-normal thyroid function (HR 1.32; 95 % CI, 1.06-1.64 for TSH and HR 0.91; 95 % CI, 0.86-0.97 for FT4). Absolute risk of developing diabetes type 2 in participants with prediabetes decreased from 35 % to almost 15 % with higher FT4 levels within the normal range.
Low and low-normal thyroid function are risk factors for incident diabetes, especially in individuals with prediabetes. Future studies should investigate whether screening for and treatment of (subclinical) hypothyroidism is beneficial in subjects at risk of developing diabetes.
Thyroid hormone is involved in the regulation of early brain development. Since the fetal thyroid gland is not fully functional until week 18-20 of pregnancy, neuronal migration and other crucial ...early stages of intrauterine brain development largely depend on the supply of maternal thyroid hormone. Current clinical practice mostly focuses on preventing the negative consequences of low thyroid hormone concentrations, but data from animal studies have shown that both low and high concentrations of thyroid hormone have negative effects on offspring brain development. We aimed to investigate the association of maternal thyroid function with child intelligence quotient (IQ) and brain morphology.
In this population-based prospective cohort study, embedded within the Generation R Study (Rotterdam, Netherlands), we investigated the association of maternal thyroid function with child IQ (assessed by non-verbal intelligence tests) and brain morphology (assessed on brain MRI scans). Eligible women were those living in the study area at their delivery date, which had to be between April 1, 2002, and Jan 1, 2006. For this study, women with available serum samples who presented in early pregnancy (<18 weeks) were included. Data for maternal thyroid-stimulating hormone, free thyroxine, thyroid peroxidase antibodies (at weeks 9-18 of pregnancy), and child IQ (assessed at a median of 6·0 years of age 95% range 5·6-7·9 years) or brain MRI scans (done at a median of 8·0 years of age 6·2-10·0) were obtained. Analyses were adjusted for potential confounders including concentrations of human chorionic gonadotropin and child thyroid-stimulating hormone and free thyroxine.
Data for child IQ were available for 3839 mother-child pairs, and MRI scans were available from 646 children. Maternal free thyroxine concentrations showed an inverted U-shaped association with child IQ (p=0·0044), child grey matter volume (p=0·0062), and cortex volume (p=0·0011). For both low and high maternal free thyroxine concentrations, this association corresponded to a 1·4-3·8 points reduction in mean child IQ. Maternal thyroid-stimulating hormone was not associated with child IQ or brain morphology. All associations remained similar after the exclusion of women with overt hypothyroidism and overt hyperthyroidism, and after adjustment for concentrations of human chorionic gonadotropin, child thyroid-stimulating hormone and free thyroxine or thyroid peroxidase antibodies (continuous or positivity).
Both low and high maternal free thyroxine concentrations during pregnancy were associated with lower child IQ and lower grey matter and cortex volume. The association between high maternal free thyroxine and low child IQ suggests that levothyroxine therapy during pregnancy, which is often initiated in women with subclinical hypothyroidism during pregnancy, might carry the potential risk of adverse child neurodevelopment outcomes when the aim of treatment is to achieve high-normal thyroid function test results.
The Netherlands Organisation for Health Research and Development (ZonMw) and the European Community's Seventh Framework Programme.
Context:
Although both overt hyper- and hypothyroidism are known to lead to cognitive impairment, data on the association between subclinical thyroid dysfunction and cognitive function are ...conflicting.
Objective:
This study sought to determine the risk of dementia and cognitive decline associated with subclinical thyroid dysfunction among prospective cohorts.
Data Sources:
We searched in MEDLINE and EMBASE from inception until November 2014.
Study Selection:
Two physicians identified prospective cohorts that assessed thyroid function and cognitive outcomes (dementia; Mini-Mental State Examination MMSE).
Data Extraction:
Data were extracted by one reviewer following standardized protocols and verified by a second reviewer. The primary outcome was dementia and decline in cognitive function was the secondary outcome.
Data Synthesis:
Eleven prospective cohorts followed 16,805 participants during a median followup of 44.4 months. Five studies analyzed the risk of dementia in subclinical hyperthyroidism (SHyper) (n = 6410), six in subclinical hypothyroidism (SHypo) (n = 7401). Five studies analyzed MMSE decline in SHyper (n = 7895), seven in SHypo (n = 8960). In random-effects models, the pooled adjusted risk ratio for dementia in SHyper was 1.67 (95% confidence interval, 1.04; 2.69) and 1.14 (95% confidence interval, 0.84; 1.55) in SHypo vs euthyroidism, both without evidence of significant heterogeneity (I2 = 0.0%). The pooled mean MMSE decline from baseline to followup (mean 32 mo) did not significantly differ between SHyper or SHypo vs euthyroidism.
Conclusions:
SHyper might be associated with an elevated risk for dementia, whereas SHypo is not, and both conditions are not associated with faster decline in MMSE over time. Available data are limited, and additional large, high-quality studies are needed.
This meta-analysis determined the risk of dementia and cognitive decline associated with subclinical thyroid dysfunction and found a possible association for subclinical hyperthyroidism and dementia.
Purpose
In clinical practice, currently one reference range for serum immunoglobulin (Ig) A, G, and M is applied to all adults, although various factors may influence Ig serum levels. ...Population-based data on determinants of IgA, IgG, and IgM and recommendations for subgroup specific reference ranges are lacking. We aimed to provide an overview of determinants of IgA, IgG, and IgM in community-dwelling middle-aged and elderly individuals and explore determinants that influence Ig reference ranges.
Methods
Within the Rotterdam Study, we performed linear regression analyses for the association of demographic, lifestyle, and cardiovascular factors with serum IgA, IgG, and IgM. We furthermore calculated Ig reference ranges (based on percentiles), both overall and within relevant subgroups.
Results
We included 8768 participants (median age 62 years). IgA and IgG increased non-linearly with higher age (
P
< .0001 for both). Women had lower IgA (beta: − 0.24; 95% confidence interval 95% CI: − 0.29; − 0.20) and IgG (beta: − 0.33; 95% CI: − 0.44; − 0.23), but higher IgM levels (beta: 0.08; 95% CI: 0.04;0.13) than men. Former and particularly current smoking were associated with lower IgA and IgG (betas between − 0.07 and − 1.03). Higher alcohol consumption was associated with lower IgG (beta for heavy drinking: − 0.70; 95% CI: − 0.91; − 0.48). Corticosteroid use was associated with lower IgG (beta: − 1.12; 95% CI: − 1.58; − 0.66). Associations with cardiovascular factors were heterogeneous and differed between sexes.
Conclusion
Age, sex, smoking, alcohol consumption, corticosteroid use, and cardiovascular factors are determinants that should be considered when interpreting serum Ig levels in middle-aged and elderly individuals and may require adjusted reference ranges.
Prolactin-secreting tumors respond well to medical management, with a few patients requiring surgery. We conducted a systematic review and meta-analysis to study the determinants of surgical ...remission in these tumors.
We searched PubMed to identify eligible studies reporting postoperative remission in patients treated with transsphenoidal surgery for prolactinoma. Primary outcomes included postoperative remission, follow-up remission, and recurrence. Postoperative and follow-up remission were defined as normoprolactinemia at <1 year and >1 year after operation, respectively. Recurrence was defined as hyperprolactinemia after initial normalization of prolactin levels. Odds ratios (ORs) were calculated, stratified by radiologic size, tumor extension, and tumor invasion, and analyzed using a random-effects model meta-analysis.
Thirty-five studies were included. Macroadenomas were associated with lower rates of postoperative remission (OR, 0.20; 95% confidence interval CI, 0.16–0.24) and lower rates of remission at follow-up (OR, 0.11; 95% CI, 0.053–0.22). Postoperative remission was less likely in tumors with extrasellar or suprasellar extension (OR, 0.16; 95% CI, 0.06–0.43) and tumors with cavernous sinus invasion (OR, 0.03; 95% CI, 0.01–0.13). Female gender and absence of preoperative dopamine agonist treatment were also associated with higher remission rates. Across the included studies, there was considerable heterogeneity in each primary outcome (postoperative remission, I2 = 94%; follow-up remission, I2 = 86%; recurrence, I2 = 68%).
Transsphenoidal surgery for prolactinomas may be particularly effective in small, noninvasive, treatment-naive tumors and may provide a viable first-line alternative to dopamine agonist therapy in such patients.
An up-to-date overview of determinants of serum immunoglobulins in adults is pivotal for clinical practice and research, but currently lacking. We therefore performed a systematic review and ...meta-analysis to identify determinants of serum immunoglobulin levels.
Embase, Web of Science, Medline, Cochrane, and Google Scholar were searched from inception to July 11
, 2019 for articles reporting on determinants of serum immunoglobulin A, G or M (IgA, IgG or IgM) in adult humans. Random and fixed effect models were applied to obtain pooled mean differences (MDs) and 95% confidence intervals (CIs) for the association of age and sex with serum immunoglobulins.
We retrieved 117 articles reporting on determinants of serum immunoglobulins, of which 28 could be meta-analyzed. Older compared to younger individuals had higher IgA (MD: 0.38; CI: 0.18 - 0.58), but lower IgM levels (MD: -0.40; 95%: -0.66 - -0.14). Men had higher IgA (MD: 0.22; CI: 0.03 - 0.42), but lower IgM levels (MD: -0.21; CI: -0.32 - -0.10) than women. Age and sex did not influence IgG. Caucasian ethnicity was associated with lower IgA, IgG, and IgM. Smoking and corticosteroid use were associated with lower IgG. Positive associations were reported of probiotics with IgG, alcohol with IgA, hypertension with IgA and IgG, and acute psychological stress with IgA, IgG, and IgM.
Older age and male sex are associated with higher IgA, but lower IgM, and urge investigation of age- and sex-specific reference ranges of immunoglobulins. Other identified determinants were ethnicity, diet, lifestyle and cardio-metabolic factors.
Background:
Intrauterine adaptation to the outside environment is an important mechanism via which the fetus increases its chance to thrive after birth. Therefore, various maternal-, pregnancy-, and ...labor-related factors are potential determinants of thyroid function of the offspring. Animal studies suggest that very high maternal thyroid hormone levels during pregnancy can alter the development of the hypothalamic-pituitary-thyroid axis set point of the child. However, to what extent maternal and birth characteristics (including maternal thyroid function, smoking, and birth weight) are associated with thyroid function of the offspring is currently unknown.
Methods:
We selected 4273 mother-child pairs from a large population-based prospective cohort with data available on maternal gestational TSH and free T4 (FT4) levels and newborn TSH and FT4 (n = 3339; at birth) or childhood TSH and FT4 (n = 2523; median age, 6 y). We used multivariable (non)linear regression models to study the association of potential determinants (including maternal TSH, FT4, thyroid peroxidase antibodies, iodine excretion, age, body mass index, smoking status, parity, pre-eclampsia, fetal distress, gestational age at birth, birth weight, mode of delivery, and thyroid function-associated single nucleotide polymorphisms) with newborn and childhood TSH and FT4.
Results:
There was a strong association of maternal TSH and FT4 levels during pregnancy with newborn and childhood TSH and FT4 levels, respectively (for both, P < .0001). Maternal FT4 was also associated with newborn TSH levels (P = .0009). Birth weight, fetal distress, gestational age at birth and maternal parity were all associated with newborn TSH and/or FT4 (P < .0001), but these associations did not persist into childhood. Genetic risk scores for TSH and FT4 were strongly associated with newborn and childhood thyroid function (P ≤ .0005). The association between maternal and offspring thyroid function did not change after correction for genetic risk scores.
Conclusions:
In this study, childhood thyroid function was predominantly determined by maternal TSH or FT4 levels and thyroid-specific single nucleotide polymorphisms. Effects of stress-related changes in thyroid function at birth were transient. Other potential factors were not associated with offspring thyroid function.
PDF
