Obstructive sleep apnea syndrome (OSAS) is characterized by complete cessation of inspiratory flow (apnea) or upper airway airflow limitation (hypopnea) with increased respiratory muscle activity, which is repeatedly observed during sleep. Hypothyroidism has been described as a rare cause of OSAS, but it is considered to be the main cause of breathing disorders during sleep in patients in whom an improvement of OSAS is observed after thyroid hormone replacement therapy. Nevertheless, euthyreosis due to thyroxine replacement in patients with OSAS often does not improve the breathing disorder and treatment with continuous positive airway pressure is usually applied. The aim of this study was to assess thyroid function in patients with OSAS. We studied 813 patients in whom severe OSAS was diagnosed; the mean apnea-hypopnea index was 44.0. Most of the patients were obese (mean BMI 33.1 ± 6.6 kg/m2) and had excessive daytime sleepiness (ESS 12.8 ± 6.6). With the thyroid stimulating hormone (TSH) concentration as the major criterion, hypothyroidism was diagnosed in 38 (4.7%) and hyperthyroidism was diagnosed in 31 (3.8%) patients. Analysis of basic anthropometric data, selected polysomnography results, and TSH, fT3, and fT4 values did not reveal any significant correlations. In conclusion, the incidence of thyroid function disorders seems to be no different in OSAS than that in the general population. We did not find correlations between TSH activity and the severity of breathing disorders during sleep.

ORIGINAL ARTICLE CPAP treatment and serum melatonin in OSA 589 models and humans have shown that melatonin secretion is strongly related to sleep, and individuals with decreased melatonin levels suffer from sleep disturbances and insomnia. This refers to elderly patients (as melatonin concentrations tend to fall with age), night-shift workers with an exogenously disrupted sleep-wake rhythm, individuals who had undergone pinealectomy, and others.1,2,10 In patients with primary insomnia, exogenous melatonin decreases sleep onset latency, increases total sleep time, and improves sleep quality. 11,12 Melatonin also effectively reduces jet INTRODUCTION Melatonin is a serotonin-derived hormone secreted by the pineal gland in a cyclic manner. 1 It has diverse activities and regulates numerous physiological processes in mammals, including the sleep-wake rhythm, sexual maturation, reproduction, and aging. It also has antioxidant, oncostatic, and immunomodulative properties.1-3 Its release responds to the light-dark cycle.4-6 The peak melatonin secretion occurs during the night hours; during the day, its concentrations are low. Exposure to light acutely suppresses nocturnal melatonin release. OBJECTIVES The aim of the study was to evaluate the profile of circadian melatonin secretion in patients with obstructive sleep apnea (OSA) and to assess the impact of 2-day and 3-month treatment with continuous airway pressure (CPAP) on diurnal and nocturnal serum melatonin levels.PATIENTS AND METHODS Serum melatonin levels were evaluated in 71 untreated patients with OSA and 18 healthy controls at 6 time points: 10 AM, 2 PM, 6 PM, 10 PM, 2 AM, and 6 AM. The measurements were repeated after 2 days and 3 months of CPAP treatment. RESULTSMelatonin secretion rhythm was altered in 25.4% of the patients with OSA. In patients with preserved secretion rhythm, the serum melatonin level was significantly lower at 2 AM and 6 AM, compared with healthy controls: 68.2 pg/ml (interquartile range [IQR], 30.1-109.8 pg/ml) vs 109.1 pg/ml (IQR, 63-167.9 pg/ml), P = 0.02 and 40.8 pg/ml (IQR,.2 pg/ml) vs 67.7 pg/ml (IQR, 32.7-131.7 pg/ml), P = 0.04, respectively. Melatonin levels did not change significantly after the 2-day and 3-month CPAP treatment. However, at 3 months, a shift of the peak melatonin concentration to 2 AM was observed in patients with an altered secretion rhythm.CONCLUSIONS OSA has a significant effect on serum melatonin levels. Neither short-term nor long-term CPAP treatment significantly changes melatonin concentrations; however, our results seem to indicate that a 3-month CPAP treatment may be helpful in restoring the physiological rhythm of melatonin secretion in patients with OSA.

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Background Patients with idiopathic pulmonary fibrosis (IPF) frequently have multiple comorbidities, which may influence survival but go under-recognised in clinical practice. We therefore report comorbidity, antifibrotic treatment use and survival of patients with IPF observed in the multi-national EMPIRE registry. Methods For this prospective IPF cohort, demographics, comorbidities, survival and causes of death were analysed. Comorbidities were noted by the treating physician based on the patient’s past medical history or as reported during follow-up. Comorbidities were defined as prevalent when noted at enrolment, or as incident when recorded during follow-up. Survival was analysed by Kaplan–Meier estimates, log-rank test, and Cox proportional hazards models. Hazard ratios (HR) were adjusted for gender, age, smoking status and FVC at enrolment. Results A population of 3,580 patients with IPF from 11 Central and Eastern European countries was followed every 6 months for up to 6 years. At enrolment, 91.3% of patients reported at least one comorbidity, whereas more than one-third (37.8%) reported four or more comorbidities. Five-year survival was 53.7% in patients with no prevalent comorbidities, whereas it was 48.4%, 47.0%, 43.8% and 41.1% in patients with 1, 2, 3 and ≥ 4 comorbidities, respectively. The presence of multiple comorbidities at enrolment was associated with significantly worse survival (log-rank test P = 0.007). Adjusted HRs indicate that risk of death was increased by 44% in patients with IPF reporting ≥ 4 comorbidities at baseline compared with no comorbidity (P = 0.021). The relationship between number of comorbidities and decreased survival was also seen in patients receiving antifibrotic treatment (63% of all patients; log-rank test P < 0.001). Comorbidity as cause of death was identified in at least 26.1% of deaths. Conclusions The majority of patients with IPF demonstrate comorbidities, and many have comorbidity-related deaths. Increasing numbers of comorbidities are associated with worse survival; and this pattern is also present in patients receiving antifibrotic therapy.