Physical findings may include an enlarged soft palate or tonsils, and a short fat neck. There is a positive correlation between sleep apnea and an increase in neck size over time. Laboratory clues include polycythemia, awake hypercapnea, or tachycardia-bradycardia syndrome while asleep if a holter monitor was ordered. Other arrhythmias occur. There is an increased incidence of systemic hypertension and pulmonary hypertension in obstructive sleep apnea patients.
Hypothyroidism can cause obstructive sleep apnea.
The gold standard test for diagnosis is the polysomnogram. Overnight trend oximetry is not an accurate screening tool - CHF and COPD can cause nocturnal hypoxia. The polysomnogram is best done in a sleep lab with a technician to monitor the study. An important part of the study is the 2 channel EEG for sleep staging. It is also useful to determine if the patient sleeps and if so, how often the sleep is fragmented.