A Case of Hypersomnolence with Subclinical Hypothyroidism Treated with Levothyroxine

ABSTRACT

We present a patient who complained of excessive daytime sleepiness (EDS), which started three years ago. She had no other medical, neurological, and psychiatric disorders. Nocturnal polysomnography did not indicate any sleep disorders, which might cause daytime EDS, such as obstructive sleep apnea. The following multiple sleep latency test was not compatible for narcolepsy. Her laboratory findings were remarkable for subclinical hypothyroidism, although free T4 and T3 were within reference rage, she had elevated thyroid stimulating hormone. After four weeks of levothyroxine treatment, her EDS resolved. The hypersomnolence, as a presenting symptom of subclinical hypothyroidism, was optimally treated after thyroid hormone replacement.