Treatment outcome and predictors of better response to thyroxin in hypothyroid patients with sleep apnea syndrome in Zagazig University hospital

Abstract

BackgroundMany studies suggest that sleep-disordered breathing (SDB) is common among patients with hypothyroidism. 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 and OSA have overlapping clinical presentations. Excessive daytime somnolence, apathy and lethargy are known to occur in patients with hypothyroidism. AimThis study was designed to detect predictors for better response to thyroxin therapy in hypothyroid patients presented with OSAS and to pick up features of other hypothyroid patients who still presented with obstructive sleep apnea and remain in need of CPAP beside thyroxin therapy, after euthyroid state had been reached. Settings and designThis randomized controlled clinical trial study was conducted in Chest and Internal Medicine departments, Zagazig University Hospitals. Patients and methodsA total of 130 patients, 65 with hypothyroidism had manifestations of OSA confirmed by sleep study (1st polysomnography) (group I) and 65 euthyroid patients with manifestations of OSA as a control subjects, were treated by CPAP (group II). After reaching euthyroid state, another sleep study (2nd polysomnography) was done, then patients were subdivided into : 40 patients whom polysomnographic study improved markedly after thyroxin therapy and advised to continue on thyroxin replacement (IA subgroup) and 25 patients showed no significant improvement and planned for CPAP therapy along with thyroid therapy (IB subgroup). ResultsNeck circumference, BMI and Epworth score were statistically significantly higher in hypothyroid group (p≤0.002, <0.001, 0.01 respectively), hypothyroid patients associated with sleep apnea more likely to have statistically longer stage 3 duration and more frequent snoring (p<0.001). 40 patients who were adviced to continue on thyroxin therapy alone had significant improvement in all sleep parameters. By retrograde analysis, patients who advised to continue on hormonal therapy alone (n=40) had statistically significant less neck circumference (p=0.022), more lower levels of TSH and higher levels of FT4 (p<0.001, 0.008) in comparison to patients continued on hormonal therapy and CPAP (n=20). ConclusionsSome hypothyroidism patients with OSA will improve on hormonal therapy alone but other will continue to need CPAP. Neck circumference, free T4 and TSH levels may help us in predicting the response of these patients.