What is the Difference Between AMH and FSH?

AMH (Anti-Müllerian Hormone) and FSH (Follicle Stimulating Hormone) are both hormones that provide insight into a woman's ovarian reserve, but they have different functions and are tested differently. Here are the main differences between AMH and FSH:

Function: AMH is produced by premature follicles that are not yet ready to release an egg, reflecting the number of very immature eggs on deck to start the journey toward maturation. FSH, on the other hand, stimulates the ovary to produce follicles and is involved in the maturation process of eggs that will be available for ovulation or egg retrieval during an IVF cycle.
Measurement: AMH levels can be measured at any time during the menstrual cycle, while FSH levels need to be measured on a specific day, usually day 3. FSH can be measured via blood or urine, whereas AMH can only be measured via blood.
Pregnancy Predictor: AMH appears to be a better predictor of pregnancy chances than FSH, especially in women aged 35 years and above. However, it does not predict pregnancy success; it predicts response at the time of an egg freezing cycle or an in-vitro fertilization (IVF).
Sensitivity and Specificity: AMH has been found to have more sensitivity (80% versus 28.57%) and almost equal specificity (78.89% versus 78.65%) compared to FSH in diagnosing Premature Ovarian Failure (POF).

In summary, while both AMH and FSH provide information about a woman's ovarian reserve, they serve different functions and have different measurement methods. AMH is considered a better predictor of pregnancy chances in certain situations, but neither hormone is definitively superior to the other. Both have their limitations and can be used in conjunction with each other for a more comprehensive understanding of a woman's ovarian reserve.