Time Course of Serum Estrogen and Luteinizing Hormone (LH) Concentrations During the Menstrual Cycle of the Rhesus Monkey

Abstract

Estradiol and LH levels were measured by radioimmunoassay in daily samples of peripheral serum of rhesus monkeys during 10 normal menstrual cycles. During the 4 days prior to the LH surge, serum estradiol values rose sharply, while the LH levels declined. The midcycle peak of estradiol and LH occurred simultaneously in 9 of the 10 cycles studied. These peaks were followed within 24 to 48 hr by an abrupt fall in estradiol levels, while LH levels declined over a 5-day period. Most animals showed no luteal phase peaks in serum estradiol concentration. A rapid and simple method for the measurement of serum “estrogen” concentrations is described which provides a good approximation of estradiol levels. (Endocrinology89:177, 1971)