Endocrine parameters may also be used to predict HAPE. For example, Cai and Yang [26] used radioimmunoassays to measure the blood levels of 18 endocrine parameters, including thyroid stimulating hormone, adrenocorticotropic hormone, and corticotropin hormone, and found that plasma cortisol <20 µg/L and urine 17-hydroxy corticosteroid (17-OHCS) levels <17 µmoL/dL could predict HAPE with an accuracy >95%.