# Monitoring sexual hormones in women going to high altitude—a pilot study

## TL;DR

This pilot study tested a new method for women to self-monitor sexual hormones at high altitudes and found it feasible, while also observing AMS incidence.

## Contribution

The study introduces a practical self-monitoring tool for sexual hormones and explores their potential link to AMS in women.

## Key findings

- The Proov kit successfully measured sexual hormones in 93.8% of cases during high-altitude exposure.
- AMS incidence was higher at 3,600 m compared to 3,100 m, with significant differences in SpO2 and LLS scores.
- Urinary PdG concentrations showed greater differences between menstrual cycle phases at higher altitudes.

## Abstract

The susceptibility to acute mountain sickness (AMS) in relation to sexual hormones in women remains elusive, partly because hormones could not be conveniently measured. We evaluated a novel kit for self-monitoring sexual hormones in women and recorded AMS incidence during high-altitude sojourns.

Two groups of healthy, premenopausal women, mean ± SD age 23.1 ± 2.3 years, residing <1,000 m underwent baseline evaluations at 760 m before travelling to and staying for 2 days and nights (48 h) at 3,100 m or 3,600 m, respectively. Participants self-monitored morning urine sexual hormone concentrations (estrone-1-glucuronide, E1G, pregnanediol-3-alpha-glucuronide, PdG, and luteinizing hormone, LH) daily for 30d including altitude sojourns using the simple “Proov” kit (MFB Fertility Inc). Follicular and luteal menstrual cycle phases detected by LH peak, altitude-related adverse health effects (ARAHE), AMS [Lake Louise score 2018 (LLS) ≥ 3 points including headache] and pulse oximetry (SpO2) were assessed.

1,172 of 1,250 (93.8%) hormone measurements were successful, 78 of 1,250 (6.2%) failed due to nonadherence or technical failure. At 3,600 m, mean differences in urinary PdG concentration were 3.8 mcg/ml (95% CI, 0.6–7.1) between luteal and follicular cycle phases. At 3,100 m, corresponding difference was 8.5 mcg/ml (95% CI, 5.0–12.0). At 3,100 m, 9 of 21 (43%) women were diagnosed with AMS with SpO2 of 93.0 ± 1.6% and LLS of 0.3 ± 1.4 in the morning after the first night. At 3,600 m, 12 of 21 (57%) women had AMS (p = 0.355 vs. 3,100 m) with SpO2 of 86.8 ± 1.8% (p < 0.05 vs. 3,100 m) and LLS of 1.9 ± 1.4 (p < 0.05 vs. 3,100 m).

Self-monitoring female sexual hormones during high-altitude field studies with the employed kit is feasible and provides physiologically plausible trends of hormone levels over the menstrual cycle. Our data provide a valuable basis for designing further studies to evaluate AMS susceptibility in women.