ARE THYROID-FUNCTION TESTS NECESSARY IN PATIENTS WITH SUSPECTED SLEEP-APNEA

Thyroid evaluation is frequently performed in patients with sleep apne a because of a suspected causal relationship between hypothyroidism an d obstructive sleep apnea (OSA). The aim of this study was to determin e the actual prevalence of hypothyroidism in patients referred for pol ysomnography and evaluate whether its rate was higher in patients with OSA than those without OSA. Ultrasensitive thyroid stimulating hormon e (TSH) was performed on 255 of 279 consecutive patients referred for polysomnography from the neurology service of a large HMO. Hypothyroid ism was detected in 1.6% (4/243) of all patients, 1.5% (3/194) of pati ents referred to evaluate OSA, and 2.0% of patients referred to evalua te the presence of periodic leg movement disorder (PLMD)/narcolepsy/ p arasomnia. There was no significant difference in rates of hypothyroid ism in patients with documented OSA (2.9%, 3/103) compared to those wi thout OSA (0.7%, 1/135). Two of the four patients with elevated TSHs h ad previously documented hypothyroidism and were on thyroxine replacem ent. Rates of hyperthyroidism were as high or higher than those of hyp othyroidism in all groups. We conclude that thyroid screening does not appear to be appropriate for patients with suspected, or confirmed, O SA in the absence of signs or symptoms consistent with hypothyroidism or unless they are in a high risk group (women over the age of 60).