Serum prolactin levels are highest
High-Yield Explanation
Normaladult serum PRL levels are about10-25 mg/Linwomenand10-20 mg/L in men. PRL secretion is pulsatile, with the highest secretory peaks occurring during rapid eye movement sleep. Peak serum PRL levels (up to 30 mg/L) occur between 4:00 and 6:00 a.m. The circulating half-life of PRL is about 50 min.