Why Did E2 Drop After 5 Months on HRT?

Hi, my friend is a trans woman, she’s been on HRT for 5 months. Her regimen is 4 mg Estrofem daily and 12.5 mg CPA.

When she started, her E2 level was 53.4 pg/ml, but now it’s dropped to 32.6 pg/ml. We’re really confused and worried because we thought it would go up, not down.

Does anyone know why this might happen?