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

Autoimmune Polyendocrine Syndrome Complicated by Pulmonary Hypertension

A 24-years old female was admitted for acute renal failure, melanoderma, hyponatremia, and hyperkalemia. The clinical suspicion of Addison's disease was confirmed by laboratory test and the appropriate replacement therapy with corticosteroids and fludrocortisone was started. In the meantime primary hypothyroidism and diabetes mellitus type 1 were disclosed and treated, thus fulfilling a diagnosis of autoimmune polyendocrine syndrome type 2. Eighteen months later she was admitted for right-sided heart failure. The work-up allowed to diagnose pulmonary arterial hypertension. Here, we report the clinical course and discuss the putative link between these two rare diseases.

Pulmonary hypertension in thyroid diseases

The influence of thyroid hormones on cardiovascular system is well established. Thyroid diseases can effectively enhance the alteration on cardiovascular system by influencing chronotropic and inotropic actions of the heart; altering the strength and the speed of contraction, the speed of relaxation, the duration of the potential of action, and the duration of the refractory period and atrio-ventricular conduction time; modulating circulation and peripheral vascular beds. One of the more intriguing insights in the connection between thyroid diseases and cardiovascular alterations is related to the evaluation of the influence of thyroid hormones on pulmonary vascular beds. Literature reported several studies regarding the association between both hypothyroidism and hyperthyroidism and the occurrence of increased vascular pulmonary arterial pressure. Nevertheless, the pathogenetic mechanisms able to explain such relationship are not fully understood. Many doubts still persist in the comprehension of the mechanisms of pulmonary hypertension in thyroid diseases. The aim of this review was to provide possible explanation about the possible interaction between pulmonary vascular beds and thyroid function in order to evaluate the possibility of novel perspectives in the general management of patients suffering from thyroid and cardiovascular diseases.

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.