Respiratory Manifestations of Hypothyroidism: A Systematic Review

Association between hypothyroidism and obstructive sleep apnea: a bidirectional Mendelian randomization study combined with the geo database

Background

The causal relationship between hypothyroidism and obstructive sleep apnea (OSA) remains controversial. Therefore, our research used a bidirectional Mendelian randomization (MR) method in an attempt to determine the causal relationship between hypothyroidism and OSA.

Methods

From the publicly accessible genome-wide association analysis (GWAS) summary database, we obtained single nucleotide polymorphism (SNPs) data pertaining to hypothyroidism and OSA. Inverse variance weighting (IVW) was the principal method of analysis utilized, with validation also conducted via weighted median, MR-Egger, simple model, and weighted model approaches. To further evaluate the robustness of the results, heterogeneity testing, pleiotropy testing, and the "leave-one-out" sensitivity analysis were performed. Differentially expressed genes (DEGs) from the OSA dataset (GSE135917) and hypothyroidism dataset (GSE176153) derived from the Gene Expression Omnibus (GEO) database were screened using the "limma" package. The "clusterProfiler" and "GO plot" packages were used for further enrichment analysis in order to validate the findings of the MR study. The Cytoscape software was utilized to build a protein-protein interaction (PPI) network of DEGs and to screen for hub genes.

Results

The MR analysis showed that genetically predicted hypothyroidism was associated with an increased risk of OSA [IVW odds ratio (OR) = 1.734; 95% confidence interval (CI) = 1.073-2.801; p = 0.025]. The trend of the outcomes of the other approaches is consistent with the trend of the IVW outcome. However, the reverse MR analysis suggested no evidence for the causal effect of OSA on hypothyroidism (IVW OR = 1.002, 95% CI: 0.996-1.009, p = 0.454). The robustness of the results was confirmed by the sensitivity analysis. Bioinformatics analysis revealed that there were DEGs that hypothyroidism and OSA have in common.

Conclusion

Our findings suggested that hypothyroidism may increase the risk of OSA, while the effect of OSA on hypothyroidism was not found in this MR study. Thus, patients with hypothyroidism should be enhanced with screening for OSA for early diagnosis and appropriate treatment.

Approach the Patient With Obstructive Sleep Apnea and Obesity

Obstructive sleep apnea (OSA) and obesity are highly prevalent and bidirectionally associated. OSA is underrecognized, however, particularly in women. By mechanisms that overlap with those of obesity, OSA increases the risk of developing, or having poor outcomes from, comorbid chronic disorders and impairs quality of life. Using 2 illustrative cases, we discuss the relationships between OSA and obesity with type 2 diabetes, dyslipidemia, cardiovascular disease, cognitive disturbance, mood disorders, lower urinary tract symptoms, sexual function, and reproductive disorders. The differences in OSA between men and women, the phenotypic variability of OSA, and comorbid sleep disorders are highlighted. When the probability of OSA is high due to consistent symptoms, comorbidities, or both, a diagnostic sleep study is advisable. Continuous positive airway pressure or mandibular advancement splints improve symptoms. Benefits for comorbidities are variable depending on nightly duration of use. By contrast, weight loss and optimization of lifestyle behaviors are consistently beneficial.

The association of lymphocyte with hypothyroidism in obstructive sleep apnea

PURPOSE

Obstructive sleep apnea (OSA) is a common sleep-breathing disorder. Numerous investigations have found a strong inherent relationship between OSA and hypothyroidism. Studies suggest that lymphocytes may be involved in the development of hypothyroidism in patients with OSA. This study aimed to assess the association between lymphocytes and hypothyroidism in OSA patients.

PATIENTS AND METHODS

This study involved 920 patients with OSA who underwent nocturnal sleep monitoring, thyroid function testing, and routine blood tests. In patients with OSA, logistic regression analysis indicated independent predictors of hypothyroidism. The cutoff level of lymphocyte count was determined using a receiver operating characteristic (ROC) analysis to predict the occurrence of hypothyroidism in individuals with OSA.

RESULTS

This study comprised 920 OSA patients (617 males and 303 women), 879 with normal thyroid function, and 41 with hypothyroidism, with a hypothyroidism incidence of 4.46%. In the entire OSA population and male OSA patients, the number of lymphocytes was significantly higher in the hypothyroid group than in the control group (p = 0.002 and 0.020, respectively). In addition, among the OSA population younger than 60 years old and patients with mild to moderate OSA, lymphocytes were found to be considerably more in the hypothyroid group than in the euthyroid group. Lymphocyte count, ESS, and sex were all independent predictors of hypothyroidism development in OSA patients. According to ROC curve analysis, the risk of hypothyroidism increases with increasing lymphocyte count in the total patient population, with an optimal diagnostic cutoff point of 2.5 (× 10*9/L).

CONCLUSIONS

The prevalence of hypothyroidism in patients with OSA increases as the number of lymphocytes increases. Lymphocyte count can be used as an independent predictor of the occurrence of hypothyroidism, and it has a diagnostic value for OSA combined with hypothyroidism.

Endocrine disorders in obstructive sleep apnoea syndrome: A bidirectional relationship

Obstructive sleep apnoea (OSA) is a common disorder characterized by recurrent episodes of apnoea or hypopnea due to total or partial pharyngeal collapse and temporary upper airway obstruction during sleep. The prevalence of OSA is increasing and currently affects about 30% of men and 13% of women in Europe. Intermittent hypoxia, oxidative stress, systemic inflammation, and sleep fragmentation resulting from OSA can provoke subsequent cardiometabolic disorders. The relationships between endocrine disorders and OSA are complex and bidirectional. Indeed, several endocrine disorders are risk factors for OSA. Compared with the general population, the prevalence of OSA is increased in patients with obesity, hypothyroidism, acromegaly, Cushing syndrome, and type 1 and 2 diabetes. In some cases, treatment of the underlying endocrine disorder can improve, and occasionally cure, OSA. On the other hand, OSA can also induce endocrine disorders, particularly glucose metabolism abnormalities. Whether continuous positive airway pressure (CPAP) treatment for OSA can improve these endocrine disturbances remains unclear due to the presence of several confounding factors. In this review, we discuss the current state-of-the-art based on the review of the current medical literature for key articles focusing on the bidirectional relationship between endocrine disorders and OSA and the effects of treatment. Screening of OSA in endocrine patients is also discussed, as it remains a subject of debate.

Pathogenetic mechanisms, clinical signs and consequences of the autoimmune thyroiditis impact on body systems (a literature review)

Background. The review analyzes the publications on the pathogenetic mechanisms and clinical consequences of the impact of autoimmune thyroiditis and hypothyroidism on body systems. Autoimmune thyroiditis is an organ-specific autoimmune disease of the thyroid gland and the most common cause of hypothyroidism in regions of the world with sufficient iodine. Sources of information. The sources of information were reports in domestic and, mostly, foreign periodicals on immunology, pathological physiology, internal medicine, and endocrinology. Synthesis of evidence. The effect of autoimmune thyroiditis on the systems of the body is implemented in two ways. The first one is accomplished through the body’s immune system, when the organ-specific immune process in the thyroid gland for unknown reasons acquires signs of systemic disease with clinical manifestations of damage to other organs and systems. The second is due to hypothyroidism, which is the logical conclusion of the autoimmune process in the thyroid. The effects of hypothyroidism on the body as a whole and its systems, in particular, are known, and the pathogenetic mechanisms are not fully understood and require in-depth study. The issues of the body's autoimmune disease, the mechanisms of its initiation and progression remain undiscovered and poorly understood. Conclusions. The effect of autoimmune thyroiditis is realized through the immune system when the organ-specific immune process in the thyroid gland for unknown reasons acquires signs of systemic disease and hypothyroidism, which is the logical conclusion of the autoimmune process in the thyroid gland. The pathogenetic mechanisms of the effects of autoimmune thyroiditis and hypothyroidism on the body are not fully understood and require in-depth study. The presented data show that over the last decade the interest in studying the problem of autoimmune thyroiditis, hypothyroidism, and their pathological significance for the body has deepened.

Pulmonary Manifestations of Endocrine and Metabolic Diseases in Children

Advances in technology, methodology, and deep phenotyping are increasingly driving the understanding of the pathologic basis of disease. Improvements in patient identification and treatment are impacting survival. This is true in endocrinology and inborn errors of metabolism, where disease-modifying therapies are developing. Inherent to this evolution is the increasing awareness of the respiratory manifestations of these rare diseases. This review updates clinicians, stratifying diseases spirometerically; pulmonary hypertension and diseases with a predisposition to recurrent pulmonary infection are discussed. This division is artificial; many diseases have multiple pathologic effects on respiration. This review does not cover the impact of obesity.

Hypothyroidism

Hypothyroidism is a common condition in which the thyroid gland provides insufficient amounts of thyroid hormone for the needs of peripheral tissues. The most common cause in adults is chronic lymphocytic thyroiditis (Hashimoto thyroiditis), but there are many other causes. Because most of the clinical features of hypothyroidism are nonspecific, the diagnosis requires laboratory testing. Serum thyroid-stimulating hormone (TSH) measurement is the best diagnostic test; an elevated TSH level almost always signals primary hypothyroidism. Serum free thyroxine levels may be below the reference range (overt hypothyroidism) or within the reference range (subclinical hypothyroidism). All patients with overt hypothyroidism should be treated, but those with subclinical hypothyroidism do not always benefit from treatment, especially elderly patients and those with baseline TSH levels below 10 mU/L. Oral L-thyroxine is the treatment of choice because of its well-demonstrated efficacy, safety, and ease of use. Therapy goals are symptom relief and maintenance of serum TSH levels within the reference range. Myxedema coma is a life-threatening form of decompensated hypothyroidism that must be treated with aggressive L-thyroxine replacement and other supportive measures in the inpatient setting.

Upper and Lower Limb Strength and Body Posture in Children with Congenital Hypothyroidism: An Observational Case-Control Study

BACKGROUND

Congenital hypothyroidism (CH) is an endocrine disease with a precocious significant impairment of growth and neuromotor development. Thyroid hormones are essential for central nervous system development, maturation, and myelination. Furthermore, thyroid hormone deficiency affects the function of several systems, including the musculoskeletal system. The disease has a significant incidence in the general population (1:3000-1:2000 newborns in Italy). The aim of the present study was to evaluate any differences in upper and lower limb strength, body sway, and plantar loading distribution in children with CH compared to healthy children.

METHODS

In this study, the case group was composed of children with CH (CHG), while the control group included healthy children (CG). Both groups comprised 19 children (CHG: female = 12; CG: female = 9). The maximum isometric handgrip strength and explosive-elastic lower limb strength were assessed with the handgrip test and the Sargent test, respectively. The stabilometric and baropodometric analyses were used to measure the Center of Pressure displacements and the plantar loading distribution between feet, respectively. The differences between groups were analyzed by a univariate analysis of covariance using as covariates weight and height with the significant level set at < 0.05.

RESULTS

We found that CHG children were shorter and thinner than CG ones (p < 0.05). No significant difference in the upper and lower limb strength was found between groups. CHG exhibited a significant greater Sway Path Length (p < 0.01) and Ellipse Surface (p < 0.05) than CG. Moreover, CHG displayed an asymmetric plantar loading distribution with a significant lower percentage in the right than in the left foot (p < 0.05). Moreover, a significant lower plantar loading percentage in the right foot of CHG than in the right foot of CG was observed (p < 0.05).

CONCLUSIONS

These findings seem to suggest that CH does not affect muscle strength in early treated children. However, these patients show poor postural control ability and asymmetric plantar loading distribution. Increasing the physical activity in these children could improve their body posture.

Hypothyroidism and Its Association With Sleep Apnea Among Adults in the United States: NHANES 2007-2008

CONTEXT

The association between hypothyroidism and sleep apnea (SA) has been studied, but results are conflicting and based mostly on small studies.

OBJECTIVE

To determine whether there is a positive association between hypothyroidism and SA in the US population.

DESIGN

Cross-sectional study.

SETTING

US National Health and Nutrition Examination Survey, 2007-2008.

PARTICIPANTS

We included all subjects ≥18 years old who met inclusion criteria. Participants not on antithyroid medication with a TSH >5.6 mIU/L and those on thyroid hormone replacement regardless of TSH were categorized as hypothyroid. Participants not on thyroid hormone replacement or antithyroid medication who had a TSH ≥0.34 and ≤5.6 mIU/L were categorized as euthyroid. The diagnosis of SA was based on participants' response when asked whether they had been diagnosed with SA by their doctors.

MAIN OUTCOME MEASURES

Multivariate logistic regression analyses were performed to determine the association between hypothyroidism and SA.

RESULTS

A total of 5515 adults were included for data analysis. The prevalence of hypothyroidism and hyperthyroidism was calculated at 9.47% and 1.19%, respectively. Multivariate logistic regression analysis adjusted for demographics, health care access, body mass index, socioeconomic factors, alcohol use, smoking, and other comorbidities demonstrated a significant association between hypothyroidism and SA (OR = 1.88, 95% CI, 1.24 to 2.84, P < 0.01).

CONCLUSION

Hypothyroidism is associated with SA after adjustment for potential confounding variables.

Respiratory arrest requiring resuscitation as a rare presentation of obstructive sleep apnoea and hypothyroidism

A 79-year-old man, who had significant cardiovascular morbidities, presented with out-of-hospital respiratory arrest. He regained breathing after brief cardiopulmonary resuscitation by his paramedic son. After meticulous investigations, acute cardiovascular events and metabolic causes were ruled out while features of obstructive sleep apnoea were elicited. The findings on in-laboratory polysomnography were compatible with severe obstructive sleep apnoea, with unusually prolonged apnoea duration of up to 2.7 min which most likely accounts for the presentation as ‘respiratory arrest’. Thyroid function test for investigation of his weight gain confirmed hypothyroidism. His symptoms improved gradually after positive airway pressure therapy with bi-level support and thyroxine replacement. On further evaluation, his hypothyroidism is believed to be a complication of long-term amiodarone exposure. The case highlights that the combination of obstructive sleep apnoea and hypothyroidism can lead to catastrophic manifestation and the unusually long apnoea could be a feature prompting further workup for possible hypothyroidism.

Physical activity in women with subclinical hypothyroidism

PURPOSE

Physical activity is associated with many health-related benefits. However, there is a shift towards inactive lifestyles around the world. Subclinical hypothyroidism (SCH) may have adverse effects similar to hypothyroidism. The presence of symptoms and reduced physical performance in SCH may contribute to an inactive lifestyle. Therefore, the present study aimed to compare physical activity levels (PALs) between women with subclinical hypothyroidism and healthy controls.

METHODS

Thirty-two women with newly diagnosed SCH and 28 healthy women were enrolled in this cross-sectional study. Arterial stiffness was evaluated by pulse wave velocity (PWV). Neuromuscular symptoms were questioned. Participants wore a physical activity monitor (SenseWear^® Armband) for 4 consecutive days. Handgrip and quadriceps muscle strength were assessed by dynamometer. Functional exercise capacity was assessed by 6-minute walk test (6MWT).

RESULTS

There was no significant difference in sociodemographic variables between the groups. PWV was significantly higher in the SCH group (P = 0.006). Physical activity duration and number of steps were significantly lower in the SCH group (P < 0.05). There was significant difference in neuromuscular symptoms, handgrip and quadriceps muscle strength, and 6MWT distance between the groups (P < 0.05).

CONCLUSIONS

This study demonstrates that women with SCH had lower PALs compared to healthy controls. Women with SCH should participate in exercise programs to increase physical activity and muscle strength to achieve adequate PALs.

Screening for High Risk of Sleep Apnea in an Ambulatory Care Setting in Saudi Arabia

Sleep apnea is a potentially serious but under-diagnosed sleep disorder. Saudi Arabia has a high prevalence of hypertension, diabetes, obesity, and smoking, which are all major risk factors for sleep apnea. However, few studies report screening for sleep apnea in Saudi Arabia. A three-month prospective, questionnaire-based study, using the Berlin Questionnaire (BQ) and the Epworth Sleepiness Scale (ESS), screened 319 patients attending a family medicine clinic in Saudi Arabia for risk of sleep apnea. The results showed that when using the BQ and the ESS, 95 (29.8%) and 102 (32.0%) respondents were at high risk of sleep apnea. Taken together, the BQ and the ESS combined measure showed that 41 (12.9%) respondents were classified as high risk for sleep apnea. Logistic regression revealed that the high risk of sleep apnea was statistically significantly (p < 0.05) associated with respondent characteristics of obesity and hypertension. No associations were found between high risk for sleep apnea and: Smoking, diabetes mellitus, hypothyroidism or hyperlipidemia. Screening for sleep apnea using the BQ and ESS questionnaires, particularly among those who are obese or hypertensive, can be a fast, valid and acceptable way of alerting the physician to this disorder among patients.

Lack of associations between thyroid function and obstructive sleep apnea severity in adults with prediabetes and diabetes mellitus

PURPOSE

Hypothyroidism is associated with a high frequency of obstructive sleep apnea (OSA). However, the prevalence of OSA in hypothyroid patients is not different from the general population in many reports. The importance of thyroid function screening in sleep-disordered breathing is still controversial. This study aimed to explore the association between thyroid dysfunction and OSA in the adults with prediabetes or diabetes mellitus type 2, who have very high prevalence of OSA.

METHODS

OSA was assessed using an in-home monitoring device, WatchPAT200. OSA severity was measured using apnea-hypopnea index (AHI), oxygen desaturation index (ODI), minimum oxygen saturation (minO2), and time spent under oxygen saturation < 90% (T90). Patients with pre-existing thyroid dysfunction were excluded.

RESULTS

Participants included 70 men and 118 women with mean age 52.8 ± 10.9 years and body mass index 28.2 ± 4.9 kg/m². One hundred forty participants (75%) had OSA, with a median AHI of 10.1 (interquartile range 4.8, 18.3). The percentage of positive thyroid autoantibody (thyroperoxidase and thyroglobulin antibody) was similar among the subjects with and without OSA. There was no correlation between the levels of thyroid function (TSH, FT3, FT4, TSH/FT3, and TSH/FT4 ratio) and the severity indices of OSA (AHI, ODI, minO2, and T90).

CONCLUSIONS

These data do not support universal screening for thyroid dysfunction in OSA patients with diabetes or prediabetes.

Prevalence of newly established thyroid disorders in patients with moderate-to-severe obstructive sleep apnea syndrome

BACKGROUND

Hypothyroidism can directly cause obstructive sleep apnea (OSA) but may also contribute to it through its impact on the metabolic syndrome. The purpose of this study was to establish the prevalence of known and newly diagnosed overt and subclinical hypothyroidism (SCH) among patients with OSA.

METHODS

We prospectively included all consecutive moderate or severe OSA patients referred for CPAP therapy. A fasting blood sample was collected to determine thyroid-stimulating hormone (TSH) and free T4 (FT4) levels.

RESULTS

A total of 280 patients were included (70% male). Mean ± SD body mass index (BMI) and apnea-hypopnea index (AHI) were 33 ± 7 kg/m² and 49 ± 25, respectively. Median (range) serum TSH levels and mean ± SD FT4 levels were comparable between severe and moderate OSA (1.7 (1.3-2.6) vs 2.1 (1.2-2.8); p = 0.378 and 15.3 ± 2.3 vs 15.3 ± 2.3; p = 0.981). TSH and FT4 levels were not correlated with AHI (p = 0.297 and p = 0.370, respectively), but TSH was correlated with BMI (p = 0.049).Of all patients, 8.9% had increased serum TSH levels (severe and moderate OSA patients had similar levels (p = 0.711)) and 8.2% were newly diagnosed patients (no differences were observed between severe and moderate OSA (p = 0.450)). A total of 16.4% of patients had some type of thyroid disorder. Thyroid function parameters were associated with BMI but not with the severity of OSA.

CONCLUSION

In our population of moderate or severe OSA, 16% of patients had a thyroid problem and 8% of these were newly diagnosed with SCH.

The effects of type 2 diabetes mellitus and its complications on physical and pulmonary functions: A case-control study

AIMS

This study was planned to determine the effects of type 2 diabetes mellitus (DM) and its complications on physical and pulmonary functions. Methods: A total of 110 individuals aged 40-65 years were included in the study, 58 with type 2 DM (study group) and 52 without DM (control group). Physical activity level, functional capacity, pulmonary function, and comorbidity levels were compared between the groups. Results: The mean age of the individuals was 52.42 ± 5.88 years. Six-minute walk test distance was 507.2 ± 51.70 m in the study group and 532.23 ± 50.32 m in the control group (p < 0.05, Cohen's d = 0.49). The pulmonary function test results of the study and control groups were determined as forced vital capacity (FVC) (%): 99.17 ± 14.13 and 104.65 ± 16.01 (p > 0.05), forced expiratory volume in one second (FEV1) (%): 96.78 ± 14.43 and 99.73 ± 15.80 (p > 0.05), and FEV1/FVC ratio: 81.97 ± 4.62 and 80.16 ± 5.27 (p > 0.05), respectively. The Charlson Comorbidity Index scores of the study and control groups were 1.83 ± 0.82 and 0.12 ± 0.32 (p < 0.05). Conclusions: Type 2 DM was associated with lower functional capacity and higher rates of comorbid diseases. Therefore, potential causes of these parameters should be considered in the rehabilitation of type 2 diabetic patients.

Diaphragmatic Palsy

The diaphragm is the primary muscle of respiration, and its weakness can lead to respiratory failure. Diaphragmatic palsy can be caused by various causes. Injury to the phrenic nerve during thoracic surgeries is the most common cause for diaphragmatic palsy. Depending on the cause, the symptoms of diaphragmatic palsies vary from completely asymptomatic to disabling dyspnea requiring mechanical ventilation. On pulmonary function tests, there will be a decrease in the maximum respiratory muscle power. Spirometry shows reduced lung functions and a significant drop of lung function in supine position is typical of diaphragmatic palsy. Diaphragmatic movements with respiration can be directly visualized by fluoroscopic examination. Currently, this test is being replaced by bedside thoracic ultrasound examination, looking at the diaphragmic excursion with deep breathing or sniffing. This test is found to be equally efficient, and without risks of ionizing radiation of fluoroscope. Treatment of diaphragmatic palsy depends on the cause. Surgical approach of repair of diaphragm or nonsurgical approach of noninvasive ventilation has been tried with good success. Overall prognosis of diaphragmatic palsy is good, except when it is related to neuromuscular degeneration conditions.