Hormone profile during the menstrual cycle at high altitude

Area of Science:

• Reproductive Endocrinology
• Human Physiology
• Altitude Medicine

Background:

• The menstrual cycle is regulated by complex hormonal interactions.
• High altitude environments present physiological challenges that can affect reproductive function.

Purpose of the Study:

• To compare the menstrual cycle hormone profiles of women at sea level and high altitude.
• To investigate potential differences in the timing of ovulation relative to gonadotropin peaks at high altitude.

Main Methods:

• Hormone levels (FSH, LH, estradiol, progesterone) were measured in women at sea level (Lima, 150 m) and high altitude (Cerro de Pasco, 4340 m).
• Ovulation was confirmed using vaginal ultrasonography.
• The study included 10 women at each altitude with regular menstrual cycles.

Main Results:

• Ovulation occurred earlier after the luteinizing hormone (LH) peak at high altitude.
• Follicle diameter was smaller at high altitude.
• Estradiol levels showed distinct patterns, with higher early follicular phase levels and sustained high levels at ovulation in high-altitude dwellers.
• Serum progesterone levels were lower at high altitude during the luteal phase.

Conclusions:

• The menstrual cycle hormone profile differs significantly between sea level and high altitude.
• These hormonal variations at high altitude are likely a consequence of reduced barometric pressure.
• The timing of ovulation and hormone production is notably altered in high-altitude environments.