Are thyroid function tests necessary in patients with suspected sleep apnea?

Investigation of the frequency of obstructive sleep apnoea syndrome in patients with subclinical hypothyroidism

Background

The aim of this study is to determine the frequency of obstructive sleep apnoea syndrome (OSAS) in a study group with the diagnosis of subclinical hypothyroidism and in a control group without the diagnosis of subclinical hypothyroidism. This study compares these two groups in terms of demographic characteristics, chronic diseases and especially polysomnographic data.

Methods

A total of 120 patients were included in this study. They consisted of 60 patients with newly diagnosed subclinical hypothyroidism and a control group of 60 patients with normal thyroid functions. Demographic, anthropometric, polysomnography data and Epworth Sleepiness Scale scores of the patients were recorded and compared.

Results

Any significant difference in the frequency and severity of OSAS was not detected. A significant difference was found in the oxygen desaturation index (ODI), the apnoea-hypopnoea index (AHI) in rapid eye movement sleep, the AHI in supine sleep position and the arousal index of the group experiencing subclinical hypothyroidism with OSAS.

Conclusion

This study showed that there was no increase in OSAS frequency in patients with subclinical hypothyroidism, but it demonstrated that the ODI and the arousal index were significantly increased in OSAS patients diagnosed with subclinical hypothyroidism. It is thought that the diagnosis and treatment of OSAS in these patients may be important in preventing cardiovascular complications.

The Course of Obstructive Sleep Apnea Syndrome in Patients With Acromegaly During Treatment

BACKGROUND

Obstructive sleep apnea syndrome (OSAS) is common in active acromegaly and negatively influences quality of life, morbidity, and mortality. This prospective study with 3 predetermined timepoints and a standardized treatment protocol investigates changes in sleep parameters during the first 2.5 years of acromegaly treatment.

METHODS

Before initiation of acromegaly treatment (medical pretreatment followed by surgery), polysomnography (PSG) was performed in 27 consecutive patients with treatment-naive acromegaly. PSG was repeated after 1 year (N = 24) and 2.5 years (N = 23), and anthropometric and biochemical parameters were obtained.

RESULTS

At baseline, 74.1% of the patients was diagnosed with OSAS. The respiratory disturbance index (RDI; P = 0.001), oxygen desaturation index (ODI; P = 0.001), lowest oxygen saturation (LSaO2; P = 0.007) and the Epworth Sleepiness Scale (ESS; P < 0.001) improved significantly during treatment, with the greatest improvement in the first year. After 2.5 years of treatment, all patients had controlled acromegaly. Of the 16 patients with repeated PSG and OSAS at baseline, 11 (68.8%) were cured of OSAS. Changes in RDI, ODI, LSaO2, and ESS correlated with insulin-like growth factor 1 levels.

CONCLUSION

OSAS has a high prevalence in active acromegaly. There is a substantial decrease in prevalence and severity of OSAS following acromegaly treatment, with the largest improvement during the first year. Most patients recover from OSAS following surgical or biochemical control of the acromegaly. Therefore, a PSG is advised after diagnosis of acromegaly. When OSAS is present, it should be treated and PSG should be repeated during acromegaly treatment.

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.

Evaluation of the Sleepy Patient: Differential Diagnosis

Excessive daytime sleepiness is defined as the inability to maintain wakefulness during waking hours, resulting in unintended lapses into sleep. It is important to distinguish sleepiness from fatigue. The evaluation of a sleep patient begins with a careful clinical assessment that includes a detailed sleep history, medical and psychiatric history, a review of medications, as well as a social and family history. Physical examination should include a general medical examination with careful attention to the upper airway and the neurologic examination. Appropriate objective testing with a polysomnogram and a multiple sleep latency test if needed will help confirm the diagnosis and direct the appropriate treatment plan.

Abnormal thyroid hormones and non-thyroidal illness syndrome in obstructive sleep apnea, and effects of CPAP treatment

OBJECTIVE

In obstructive sleep apnea (OSA), while both hypothyroidism and hyperthyroidism have been studied, the occurrence of non-thyroidal illness syndrome (NTIS) (normal thyroid stimulating hormone [TSH] with low triiodotironine) has not been investigated. We explored the occurrence of NTIS in patients with moderate to severe OSA and its relationship to the severity of nocturnal respiratory disorders. We also studied the occurrence of subclinical hypothyroidism (SH, ie, high TSH with normal thyroxine) in OSA and changes in circulating TSH, free triiodotironine (fT3) and free thyroxine (fT4) after CPAP treatment.

METHODS

After a nocturnal respiratory polysomnography, 125 consecutive patients with moderate to severe OSA and 60 control subjects with normal nocturnal respiration were recruited. Morning circulating TSH, fT3, and fT4 were measured in all subjects. In a subsample of patients, nocturnal polysomnography and hormonal determinations were repeated after CPAP treatment for five months.

RESULTS

NTIS was found in 13 (10.4%), and SH in ten (8%) OSA subjects, but not in any control subjects. Patients with NTIS showed worse mean nocturnal oxygen saturation and time with saturation <90% (both p < 0.001). After treatment, NTIS subjects (n = 13) showed an increase in fT3 (p < 0.001) to the normal range, and SH subjects (n = 6) a slight decrease in TSH (p = 0.01). In the patients with normal hormones before treatment (n = 45), no change was observed.

CONCLUSIONS

NTIS may occur in OSA patients with severe nocturnal hypoxemia. OSA treatment is followed by an improvement in TSH in patients with abnormal baseline levels of this hormone, and by recovery of NTIS.

The effect of obstructive sleep apnea syndrome and hypothyroidism to intima-media thickness of carotid artery

AIM

Obstructive sleep apnea syndrome (OSAS) is a common disorder and in subjects with OSAS the prevalence of hypothyroidism is approximately 1.2-11 %. The episodes of hypoxia/reoxygenation associated with the respiratory disturbances observed in subjects with OSAS increases the risk of cardiovascular diseases. Hypothyroidism; primary or subclinical, has several effects on cardiovascular system. In our study, we investigated carotid artery intima-media thickness (IMT) which is an early sign of atherosclerosis, in OSAS subjects with hypothyroidism.

MATERIALS AND METHOD

Subjects who admitted to Kahramanmaras Necip Fazıl City State Hospital Chest Diseases out-patient clinic between May 2014 and January 2016 for snoring and had polysomnographic evaluation at the sleep laboratory were included in this study. Each subject was evaluated for serum thyroid function tests and carotid artery IMT was measured by a Doppler ultrasound.

RESULTS

Mean carotid artery IMT values in the isolated OSAS, OSAS plus hypothyroidism, and control groups were 0.67 ± 0.12, 0.8 ± 0.12, and 0.54 ± 0.08 mm, respectively; difference between groups was statistically significant (p < .05). A poXsitive correlation was found between thyroid stimulating hormone levels and IMT (r = 0.426, p = .002), while free T3 levels and IMT were negatively correlated (r = -0.463, p = .001). IMT and apnea-hypopnea index were also positively correlated (r = 0.403, p = .003).

CONCLUSION

We suggest, physicians should be alert for hypothyroidism comorbidity in OSAS, and suspected subjects with OSAS should be screened for hypothyroidism considering the potential cardiovascular complications.

Role of hypothyroidism in obstructive sleep apnea: a meta-analysis

OBJECTIVE

This study evaluates the role of hypothyroidism in obstructive sleep apnea (OSA) by comparing the OSA indices in hypothyroid OSA (OSA-HYPOT) with euthyroid OSA (OSA-EUTHY) patients.

METHODS

After literature search in several electronic databases and selection of studies by following eligibility criteria, meta-analyses of mean differences/standardized mean differences were performed to compare OSA indices at the time of diagnosis between OSA-HYPOT and OSA-EUTHY patients. Metaregression analyses were carried out to examine the relationship between age, BMI, sample size, and gender vs OSA indices in OSA-HYPOT patients.

RESULTS

Twelve studies and five case reports recruiting 192 OSA-HYPOT and 1423 OSA-EUTHY patients were included in the meta-analysis. Prevalence (mean ± SD) of clinical hypothyroidism in OSA patients was 8.12 ± 7.13% and that of subclinical hypothyroidism 11.07 ± 8.49%. Apnea-Hypopnea Index, time of sleep with oxygen desaturation <90%, and Epworth Sleepiness Scale were significantly higher in the OSA-HYPOT patients at diagnosis, whereas there was no significant difference in arousal index, respiratory disturbance index and sleeping efficiency between OSA-HYPOT and OSA-EUTHY patients. Body mass index was positively associated with Apnea-Hypopnea Index in OSA-HYPOT patients.

CONCLUSIONS

Hypothyroidism is found to be associated with severity of OSA. However, obesity can be a confounder in the outcomes observed herein.

Relationship between sleep apnea and thyroid function

PURPOSE

Sleep apnea is sometimes associated with hypothyroidism, but the significance of thyroid function screening in sleep apnea patients has been controversial. In the present study, we investigated the relationship between thyroid function and sleep apnea in subjects who were suspected to have sleep apnea.

METHODS

We enrolled 156 consecutive subjects suspected of having sleep apnea. Subjects included 117 men and 39 women aged 21 to 84 years. They underwent nocturnal multichannel polysomnography during a one-night hospitalization. The examined indices of sleep apnea were apnea-hypopnea index (AHI), lowest oxygen saturation, oxygen desaturation index, longest apnea duration, mean apnea duration, and the percent of apnea time to sleep time. Serum thyroid-stimulating hormone (TSH), free triiodothyronine (FT3), and free thyroxine (FT4) were concomitantly measured by electrochemiluminescence immunoassays.

RESULTS

Three subjects (1.9 %) were diagnosed with primary hypothyroidism (high TSH and low FT4), and one subject (0.6 %) with subclinical hypothyroidism (high TSH and normal FT4). No significant difference in the level of TSH, FT3, or FT4 was seen among subjects with different severity of sleep apnea. The mean apnea duration significantly correlated with TSH in both simple and multiple regression analyses. Subjects with lower FT3 (≤3.75 pg/ml) showed longer mean apnea time compared to those with higher FT3 (>3.75 pg/ml) (24.9 ± 0.8 vs. 20.2 ± 1.2 s; P = 0.009). The other indices of sleep apnea did not show significant correlation with thyroid function.

CONCLUSIONS

These results suggest that the mean apnea duration and TSH/FT3 may be helpful in understanding reciprocity between the two disease states, and for evaluating the validity of thyroid function tests in patients with sleep apnea.

The incidence and severity of pulmonary hypertension in obstructive sleep apnea with hypothyroidism

BACKGROUND

Hypothyroidism and obstructive sleep apnea (OSA) are both common health problems and can be seen together. Each of these 2 diseases can cause pulmonary hypertension (PH). We aimed to determine whether hypothyroidism with OSA has a significant effect on the frequency and severity of PH.

MATERIAL AND METHODS

A total of 236 patients were included in the study. Patients were divided into 3 groups: Group I, Obstructive Sleep Apnea (n=149); Group II, Hypothyroidism (n=56); and Group III, Obstructive Sleep Apnea-Hypothyroidism (n=31). All patients underwent polysomnography and echocardiography and serum levels of thyroid-stimulating hormone (TSH) and free thyroxine 4 (FT4) were analyzed.

RESULTS

There were 167 male and 69 female participants, and the mean age was 47.8 ± 11.5 (Group I: 81.9% male, 18.1% female; Group II: 44.6% male, 55.4% female; Group III: 64.6% male, 35.4% female). Distribution of mean pulmonary arterial pressure on echocardiography was statistically different among the 3 groups (x(2)=14.99, p=0.006). When adjusted according to the apnea-hypopnea index (AHI), age, and body mass index (BMI), a significant relation with PH was determined (p=0.002).

CONCLUSIONS

The combination of hypothyroidism with OSA is associated with an increased frequency and severity of PH. When PH is found out of line with the severity of OSA, thyroid dysfunction should be investigated.

Prevalence of sleep abnormalities and their association among hypothyroid patients in an Indian population

OBJECTIVE

To estimate the prevalence of sleep abnormalities and their association with hypothyroidism and metabolic risk factors in a relatively lean urban South Indian population.

METHODS

This population-based, cross-sectional study was carried out in the urban population of Chennai, one of the largest metropolitan cities of India. Phase 1 was conducted in the field and involved a door-to-door survey of 26,000 individuals. In phase 2, every tenth subject recruited in phase 1 (n=2600) was invited to our centre for detailed anthropometric and biochemical measurements. For the current study, a subset of 358 subjects with positive family history of hypothyroidism was randomly selected. A validated questionnaire assessing various sleep abnormalities (snoring, daytime sleepiness, lack of refreshing sleep and number of hours of sleep) was administered. Anthropometric and biochemical measurements were obtained to assess metabolic risk factors including thyroid status.

RESULTS

Snorers were more often male, older, smokers and had higher BMI, neck circumference, blood pressures, and hypothyroidism. Out of 358 patients, 133 had impaired thyroid function (37.1%) and 64 patients had both snoring and impaired thyroid function (17.8%). Subjects with daytime sleepiness had higher BMI and neck obesity. The overall prevalence of snoring and daytime sleepiness was 52% and 64%, respectively. Both sleep measures were associated with hypothyroid status. Metabolic syndrome was significantly associated with snoring even after adjusting for age, sex, family history of hypothyroidism, physical activity, smoking and alcohol.

CONCLUSIONS

The prevalence of snoring and daytime sleepiness is high among urban South Indians who are relatively lean. Both disorders are associated with hypothyroidism, although these associations were stronger in those with obesity. Based on our case prevalence and the other reports cited previously, we can reasonably conclude that thyroid screening of sleep clinic patients is essential.

Correlation of clinical profiles with obstructive sleep apnea and metabolic syndrome

BACKGROUND

Obstructive sleep apnea (OSA) is a common condition being increasingly recognized and is associated with many diseases. Few data are available for Indian patients and public health hazard of the condition continues to be seriously underestimated in this country. The objective of this study was to evaluate the prevalence of obesity, hypertension, diabetes mellitus, and hyperlipidemia (HLP) in a South Indian population with proven OSA.

METHODS

A retrospective analysis of data accrued in patients undergoing polysomnography (PSG) was undertaken. Two hundred thirty-four patients of either sex in the age of 54 ± 11 years who tested positive for OSA were compared with control group. An apnea-hypopnea index (AHI) of >5 in the presence of snoring and daytime somnolence was taken to define sleep apnea.

RESULTS

The mean AHI among the study group with OSA was 31.3 ± 18.6 as compared with 1.2 ± 0.5 in the control group. The BMI among patients with OSA was 36 ± 6 as compared with 29 ± 4 in comparison group (p < 0.001). Among the patients with OSA, 31% were having HLP, 59% were diabetics, and 86% were hypertensive. Subjects with PSG-proven OSA had significant levels of day time sleepiness, lack of concentration, changes in mood, morning headache, and dry mouth. Nonrestorative sleep, awakening with choking, nocturnal dyspnea, insomnia with frequent awakenings, nocturia, and diaphoresis were observed in (>80%) patients. A significant difference in the sleep efficiency (16%), sleep onset (14%), and mean saturation (9%) was observed in the study group as compared to the control group.

CONCLUSIONS

The risk of obesity, hypertension, diabetes mellitus, and HLP in OSA syndrome patients was almost three times more than that of the comparing group.

Evaluation and management of sleep disturbance during the menopause transition

Sleep disturbances in midlife women are common and have been associated with the menopause transition itself, symptoms of hot flashes, anxiety and depressive disorders, aging, primary sleep disorders (i.e., obstructive sleep apnea, periodic limb movement disorder), comorbid medical conditions and medications, as well as with psychosocial and behavioral factors. Because there are several common sources of sleep problems in midlife women, the cause of an individual woman's sleep disturbance may be multifactorial. Effective behavioral and pharmacological therapies are available to treat sleep disturbances of different etiologies. This review provides an overview of different types of sleep disturbance occurring in midlife women and presents data supporting the use of hormone therapy, hypnotic agents, and behavioral strategies to treat sleep problems in this population. The review aims to equip clinicians evaluating menopause-age women with the knowledge and evaluation tools to diagnose, engage sleep experts where appropriate, and treat sleep disturbance in this population. Sleep disorders in midlife women should be treated because substantial improvements in quality of life and health outcomes are achievable.

Severe hypothyroidism presenting as obstructive sleep apnea

A 5-year-old child with Down syndrome (DS) diagnosed with mild to moderate obstructive sleep apnea (OSA) and subsequently found to have severe hypothyroidism is presented. Following 3 months of treatment with levothyroxine, she had full resolution of her OSA. This case underscores the importance of routine thyroid function screening in children with DS and demonstrates that OSA in children with DS can be caused by other underlying medical issues that themselves require therapy, such as the hypothyroidism in this child. Although empiric testing of thyroid function is not recommended as part of the routine workup of patients with OSA, when caring for children at higher risk for thyroid dysfunction, such as those with DS, it is important to establish whether or not it is present, as treating it may bring about partial or full resolution of the OSA, as was shown to occur in this patient.

Endocrine aspects of obstructive sleep apnea

CONTEXT

Some endocrine and metabolic disorders are associated with a high frequency of obstructive sleep apnea (OSA), and treatment of the underlying endocrine disorder can improve and occasionally cure OSA. On the other hand, epidemiological and interventional studies suggest that OSA increases the cardiovascular risk, and a link between OSA and glucose metabolism has been suggested, via reduced sleep duration and/or quality.

EVIDENCE ACQUISITION

We reviewed the medical literature for key articles through June 2009.

EVIDENCE SYNTHESIS

Some endocrine and metabolic conditions (obesity, acromegaly, hypothyroidism, polycystic ovary disease, etc.) can be associated with OSA. The pathophysiological mechanisms of OSA in these cases are reviewed. In rare instances, OSA may be improved or even cured by treatment of underlying endocrine disorders: this is the case of hypothyroidism and acromegaly, situations in which OSA is mainly related to upper airways narrowing due to reversible thickening of the pharyngeal walls. However, when irreversible skeletal defects and/or obesity are present, OSA may persist despite treatment of endocrine disorders and may thus require complementary therapy. This is also frequently the case in patients with obesity, even after substantial weight reduction.

CONCLUSIONS

Given the potential neurocognitive consequences and increased cardiovascular risk associated with OSA, specific therapy such as continuous positive airway pressure is recommended if OSA persists despite effective treatment of its potential endocrine and metabolic causes. "Apropos of sleep, that sinister adventure of all our nights, we might say that men go to bed daily with an audacity that would be incomprehensible if we did not know that it is the result of ignorance of the danger." Charles Baudelaire, in "Fusées, IX"

Neuroendocrine alterations in obese patients with sleep apnea syndrome

Obstructive sleep apnea syndrome (OSAS) is a serious, prevalent condition that has significant morbidity and mortality when untreated. It is strongly associated with obesity and is characterized by changes in the serum levels or secretory patterns of several hormones. Obese patients with OSAS show a reduction of both spontaneous and stimulated growth hormone (GH) secretion coupled to reduced insulin-like growth factor-I (IGF-I) concentrations and impaired peripheral sensitivity to GH. Hypoxemia and chronic sleep fragmentation could affect the sleep-entrained prolactin (PRL) rhythm. A disrupted Hypothalamus-Pituitary-Adrenal (HPA) axis activity has been described in OSAS. Some derangement in Thyroid-Stimulating Hormone (TSH) secretion has been demonstrated by some authors, whereas a normal thyroid activity has been described by others. Changes of gonadal axis are common in patients with OSAS, who frequently show a hypogonadotropic hypogonadism. Altogether, hormonal abnormalities may be considered as adaptive changes which indicate how a local upper airway dysfunction induces systemic consequences. The understanding of the complex interactions between hormones and OSAS may allow a multi-disciplinary approach to obese patients with this disturbance and lead to an effective management that improves quality of life and prevents associated morbidity or death.

Clinical manifestations and consequences of obstructive sleep apnea

Obstructive sleep apnea is a common respiratory disorder that is underdiagnosed and associated with a variety of adverse health and safety consequences. Treatment is effective in improving quality of life and reducing morbidity. This underscores the importance of considering the diagnosis in suitable patients, verifying the diagnosis, and initiating prompt, effective therapy. In this review, the risk factors, symptoms and signs, diagnosis, clinical consequences, and treatment of obstructive sleep apnea are discussed.

Sleep-related problems in common medical conditions

Common medical problems are often associated with abnormalities of sleep. Patients with chronic medical disorders often have fewer hours of sleep and less restorative sleep compared to healthy individuals, and this poor sleep may worsen the subjective symptoms of the disorder. Individuals with lung disease often have disturbed sleep related to oxygen desaturations, coughing, or dyspnea. Both obstructive lung disease and restrictive lung diseases are associated with poor quality sleep. Awakenings from sleep are common in untreated or undertreated asthma, and cause sleep disruption. Gastroesophageal reflux is a major cause of disrupted sleep due to awakenings from heartburn, dyspepsia, acid brash, coughing, or choking. Patients with chronic renal disease commonly have sleep complaints often due to insomnia, insufficient sleep, sleep apnea, or restless legs syndrome. Complaints related to sleep are very common in patients with fibromyalgia and other causes of chronic pain. Sleep disruption increases the sensation of pain and decreases quality of life. Patients with infectious diseases, including acute viral illnesses, HIV-related disease, and Lyme disease, may have significant problems with insomnia and hypersomnolence. Women with menopause have from insomnia, sleep-disordered breathing, restless legs syndrome, or fibromyalgia. Patients with cancer or receiving cancer therapy are often bothered by insomnia or other sleep disturbances that affect quality of life and daytime energy. The objective of this article is to review frequently encountered medical conditions and examine their impact on sleep, and to review frequent sleep-related problems associated with these common medical conditions.

Influence of subclinical hypothyroidism and T4 treatment on the prevalence and severity of obstructive sleep apnoea syndrome (OSAS)

BACKGROUND

Obstructive sleep apnoea (OSA) and subclinical hypothyroidism are relatively frequent disorders that may be causally linked. However, discordant results exist on the prevalence and severity of OSA in subclinical hypothyroidism. The aim of this study was to compare the prevalence and severity of sleep-disordered breathing in individuals with or without subclinical hypothyroidism, and to investigate the possible effect of levothyroxine treatment on these patients.

PATIENTS AND METHODS

One hundred and eight subjects were consecutively enrolled and divided in 3 groups, according to the TSH levels and levothyroxine therapy. The first group (Group A) was represented by 63 subjects with normal TSH and thyroid function. The other two groups included patients affected by subclinical hypothyroidism; one group (Group B) treated with levothyroxine, while the other group (Group C) was never treated with levothyroxine. Anthropometric, respiratory and polysomnographic data were evaluated in all individuals.

RESULTS

The percentage of OSA, neck circumference, and body mass index (BMI) were not statistically different among the 3 groups. Respiratory disturbance index (RDI) as well as the percentage of the total number of events (apnoea-hypopnoea) by total sleep time (TST) with <90% oxyhemoglobin saturation (TSTSaO2 <90%) were not different among the groups. When we observed OSA patients, the only significant difference between groups B and C was represented by the Epworth Sleepiness Scale (ESS) (p=0.005).

CONCLUSION

This study shows that subclinical hypothyroidism and treatment with levothyroxine do not influence the prevalence and severity of OSA, while sleep propensity is increased by untreated subclinical hypothyroidism.

Obstructive Sleep Apnea-Hypopnea Syndrome

OSAHS should be an expected condition in many patients encountered by primary care providers. The diagnosis may arise because of patient daytime dysfunction, partner prompting, or in the course of managing comorbidities adversely influenced by the hemodynamic, neural, humoral,and inflammatory consequences of repetitive desaturations and arousals.OSAHS should be suspected in patients who exhibit habitually loud snoring, witnessed apneas/choking/gasping during sleep, hypertension, neck circumferences of 17 inches or greater, obesity, and laterally narrowed oropharynxes. Diagnosis is established by polysomnography. CPAP is the treatment of choice for most patients. Education, follow-up, and heated humidification may help bolster compliance. Lifestyle modifications, oral appliances, and upper surgeries are additional treatment options.

High prevalence of previously unknown subclinical hypothyroidism in obese patients referred to a sleep clinic for sleep disordered breathing

BACKGROUND AND AIM

To evaluate the prevalence of previously unknown hypothyroidism in adult male and female patients with a wide range of body mass index (BMI) values, referred to a Sleep Clinic because of sleep disordered breathing (SDB).

METHODS AND RESULTS

Serum concentrations of thyroid stimulating hormone (TSH) and free thyroxin (fT4), as well as forced vital capacity (FVC), PaO2, PaCO2, the Epworth sleepiness scale (ESS), respiratory disturbance index (RDI), loud snoring, and the percentage of total sleep time (TST) with <90% oxyhemoglobin saturation (TST(saO2<90%)) were measured in 78 overweight and obese adult subjects with no previous diagnosis of hypothyroidism (age: 18-72 years). The prevalence of previously undiagnosed subclinical hypothyroidism in the population as a whole was 11.5%. BMI, TSH and ESS were significantly higher in the hypothyroid than the euthyroid subjects, but there was no significant between-group difference in RDI, TST(saO2<90%) or the other investigated variables, including the prevalence of obstructive sleep apnea (OSA). Among the hypothyroid individuals, BMI, neck circumference, ESS, RDI and TST(Sao2<90%) were significantly higher in those with than in those without OSA. Furthermore, there was a clear trend towards a lower FVC% and higher snoring score in the OSA patients.

CONCLUSIONS

Our results demonstrate a higher prevalence of hypothyroidism than that commonly reported in overweight and obese individuals referred to a Sleep Clinic for polysomnography because of SDB, thus suggesting that thyroid function should be evaluated in all obese patients suffering from SDB despite economic concerns.

Obese patients with obstructive sleep apnoea syndrome show a peculiar alteration of the corticotroph but not of the thyrotroph and lactotroph function

OBJECTIVE

Obstructive sleep apnoea syndrome (OSAS) is strongly associated with obesity (OB) and is characterized by several changes in endocrine functions, e.g. GH/IGF-I axis, adrenal and thyroid activity. It is still unclear whether these alterations simply reflect overweight or include peculiar hypoxia-induced hormonal alterations. Hormonal evaluations have been generally performed in basal conditions but we have recently reported that OSAS is characterized by a more severe reduction of the GH releasable pool in comparison to simple obesity. We aimed to extend our evaluation of anterior pituitary function to corticotroph, thyrotroph and lactotroph secretion under dynamic testing in OSAS in comparison with simply obese and normal subjects.

SUBJECTS AND METHODS

In 15 male patients with OSAS [age, mean +/- SEM 43.5 +/- 1.6 years; body mass index (BMI) 39.2 +/- 3.1 kg/m2; apnoea/hypopnoea index, (AHI) 53.4 +/- 8.7], 15 male patients with simple obesity (OB, age 39.7 +/- 1.2 years; BMI 41.2 +/- 2.0 kg/m2; AHI 3.1 +/- 1.2 events/h of sleep) and in 15 normal lean male subjects (NS, age 38.2 +/- 1.4 years; BMI 21.2 +/- 0.8 kg/m2; AHI 1.9 +/- 0.8 events/h of sleep) we evaluated: (a) the ACTH and cortisol responses to CRH [2 microg/kg intravenously (i.v.)] and basal 24 h UFC levels; (b) the TSH and PRL responses to TRH (5 microg/kg iv) as well as FT3 and FT4 levels.

RESULTS

Twenty-four-hour UFC levels in OSAS and OB were similar and within the normal range. Basal ACTH and cortisol levels were similar in all groups. However, the ACTH response to CRH in OSAS (Deltapeak: 30.3 +/- 3.8 pmol/l; DeltaAUC: 682.8 +/- 128.4 pmol*h/l) was markedly higher (P < 0.001) than in OB (Deltapeak: 9.3 +/- 1.4 pmol/l; DeltaAUC 471.5 +/- 97.3 pmol*h/l), which, in turn, was higher (P < 0.05) than in NS (Deltapeak: 3.3 +/- 0.9 pmol/l; DeltaAUC 94.7 +/- 76.7 pmol*h/l). On the other hand, the cortisol response to CRH was not significantly different in the three groups. Basal FT3 and FT4 levels as well as the TSH response to TRH were similar in all groups. Similarly, both basal PRL levels and the PRL response to TRH were similar in the three groups.

CONCLUSIONS

With respect to patients with simple abdominal obesity, obese patients with OSAS show a more remarkable enhancement of the ACTH response to CRH but a preserved TSH and PRL responsiveness to TRH. These findings indicate the existence of a peculiarly exaggerated ACTH hyper-responsiveness to CRH that would reflect hypoxia- and/or sleep-induced alterations of the neural control of corticotroph function; this further alteration is coupled to the previously described, peculiar reduction of somatotroph function.

Should Women with Obstructive Sleep Apnea Syndrome Be Screened for Hypothyroidism?

This study was conducted to determine if there is a significant increase in prevalence of hypothyroidism in women with OSAS such that screening might be warranted. Women undergoing polysomnography (PSG) at Duke University between January 1, 2000 and August 21, 2001 were considered for enrollment. Those with a respiratory disturbance index (RDI) >/= 10 were included for further analysis. Demographic data and documentation of thyroid testing was obtained. Thyroid testing obtained within 1 year of the PSG was used for this study. Demographic data of the euthyroid and hypothyroid groups were compared. Prevalence of hypothyroidism was calculated and compared with the prevalence of hypothyroidism in the Framingham study. A total of 118 women had OSAS per PSG. Seventy-five patients had thyroid function testing within 1 year of PSG evaluation. The mean age, body mass index, and RDI in the euthyroid and hypothyroid groups were not significantly different. The prevalence of hypothyroidism was 9.3%; the established prevalence of hypothyroidism in women in the general population is 5.9%. There was no statistically significant difference in the prevalence between these groups. The prevalence of hypothyroidism in women with OSAS is no higher than that seen in the general population. Screening women with symptoms of OSAS for hypothyroidism is unlikely to be useful.

Behavioral and pharmacologic therapy of obstructive sleep apnea

Previous attempts at using pharmacologic agents in the treatment of OSA have been disappointing. Medroxyprogesterone has not been found to be useful in the treatment of OSA. Use of protriptyline is limited by frequent side effects, but its role in mild and REM-related OSA must be clarified. SSRIs seem to be ineffective in treatment of severe OSA. Further studies are needed to determine their effect in persons with mild disease. This is important because patients with mild OSA (AHI < 15 hours) are most likely to be noncompliant with CPAP therapy [91]. A recent systematic review of drug treatments for OSA concluded that the current data do not support the use of any drug as an alternative to CPAP [92]. Of 56 studies identified, only 9 studies met methodologic criteria. Clearly, basic research and adequately powered clinical trials are needed to identify an effective medication for OSA.

What are the nonsurgical treatment options for obstructive sleep apnea syndrome?

Obstructive sleep apnea (OSA) syndrome is now recognized as a relatively common cause of excessive daytime sleepiness, with resultant psychosocial impairment and motor vehicle accidents, and it likely contributes to premature cardiovascular disease. Treatment is naturally directed at the upper airway; however, it is also important to identify and correct significant risk factors, such as obesity and hypothyroidism, whenever possible. Oral appliances or nasal continuous positive airway pressure may immediately reverse symptoms caused by OSA and can be used either indefinitely or as a bridge to potentially definitive surgery.

Thyroid Testing and Thyroid Hormone Replacement in Patients with Sleep Disordered Breathing

The current literature recommends that patients who have symptoms of sleep disordered breathing should be evaluated for hypothyroidism. Thyroid hormone replacement therapy has been reported by some authors to be effective in treating obstructive sleep apnea in hypothyroid patients. The present study prospectively evaluated the prevalence of hypothyroidism in 1,000 consecutively presenting patients who came to the office for evaluation of snoring or obstructive sleep apnea syndrome. The authors also examined the efficacy of treatment for hypothyroidism on sleep apnea in patients with both disorders.

Of the 1,000 patients, routine thyroid testing was performed on 834; only 10 of these patients (1.2%) were discovered to have previously undiagnosed clinical hypothyroidism. Four of the 10 patients with newly diagnosed clinical hypothyroidism had obstructive sleep apnea syndrome, and they received thyroid hormone replacement therapy. Once these four patients achieved a euthyroid state, repeat polysomnography showed that there was no significant difference between their pre- and posttreatment respiratoiy disturbance index.

Based on the results of our study, we conclude the following: 1) The prevalence of hypothyroidism in patients who are evaluated for sleep disordered breathing is no greater than that of the general population. 2) Thyroid replacement therapy results in little or no improvement in sleep apnea in patients with clinical hypothyroidism. 3) Routine thyroid function screening is not indicated for patients who are being evaluated for sleep disordered breathing.

Screening for hypothyroidism in sleep apnea

Primary sleep apnea-hypopnea syndrome (obstructive sleep apnea [OSA]) and hypothyroidism have many signs and symptoms in common. The overlap in clinical presentation, and the sleep-disordered breathing that can accompany hypothyroidism, create a significant risk of misdiagnosis of sleep apnea among patients referred to sleep clinic who have undiagnosed hypothyroidism. We determined the point prevalence of hypothyroidism in our sleep clinic patients with newly diagnosed sleep-disordered breathing. Of 290 sequential patients referred to sleep clinic, 200 (69%) patients judged at high risk for OSA underwent polysomnography (PSG) and biochemical screening for hypothyroidism. Of these, 124 (62%) were judged to have sleep apnea. This included three patients (1.5% of patients undergoing PSG or 2. 4% of those judged to have OSA) who were also discovered to have previously undiagnosed hypothyroidism. These three patients with "secondary" sleep apnea were treated with thyroxine therapy alone, and followed with sequential sleep studies and serum thyroid hormone assays; symptoms, sleep-disordered breathing, nocturnal hypoxia, and thyroid deficiency resolved simultaneously. We conclude that biochemical screening for hypothyroidism is required to prevent inadvertent misdiagnosis of hypothyroid sleep-disordered breathing as primary sleep apnea, and that it is a cost-effective component of the investigation of sleep apnea.

Association of hypothyroidism and obstructive sleep apnea

Obstructive sleep apnea (OSA) and hypothyroidism are relatively common disorders that have similar clinical features and are thought to be causally linked. We sought to determine the prevalence of previously unrecognized hypothyroidism in a series of patients evaluated for OSA and whether an association between hypothyroidism and OSA was present. Chart review was used to obtain information on thyroid function status, polysomnography results, levothyroxine use, and clinical signs and symptoms in 336 consecutive adult patients who underwent polysomnography for suspected OSA. In addition, levothyroxine use was determined in age- and sex-matched control subjects for the purposes of a case-control study. Among the patients without prior history of hypothyroidism who underwent polysomnography and thyroid function testing, four new cases or 1. 41% (95% CI 0.04-2.78) were found to have subclinical hypothyroidism. Our findings do not support routine thyroid screening by specialists in patients referred for polysomnography. The odds ratio of the association of prior history of hypothyroidism to OSA was 1. 47 (95% CI 0.8-2.8). Limitations in study design may have limited our ability to detect a statistically significant association between OSA and hypothyroidism.