What does an elevated Luteinizing Hormone (LH) to Follicle-Stimulating Hormone (FSH) ratio imply?

From the Guidelines

An elevated Luteinizing Hormone (LH) to Follicle-Stimulating Hormone (FSH) ratio, typically exceeding 2, implies Polycystic Ovary Syndrome (PCOS) in women, as suggested by recent data 1. This hormonal imbalance is a key diagnostic indicator of PCOS, though not the sole criterion. The LH to FSH ratio is often used to distinguish between PCOS and other conditions, such as functional hypothalamic amenorrhea (FHA).

• In PCOS, the pituitary gland releases excessive LH compared to FSH, disrupting normal ovarian function, leading to increased androgen production, and causing symptoms like irregular menstruation, acne, hirsutism, and fertility challenges.
• A recent study found that a LH to FSH ratio <1 was present in about 82% of FHA patients 1, highlighting the potential of this ratio as a diagnostic tool.
• However, it's essential to consider other diagnostic factors, including a focused history and examination, pelvic ultrasound, and laboratory evaluation, to accurately diagnose PCOS or other conditions.
• The use of parameters, such as endometrial thickness and ultra-sensitive oestradiol assays, can also aid in diagnosis, although their availability may be limited in some centers 1.

From the Research

Implications of LH to FSH Ratio

The LH to FSH ratio is a significant indicator in the diagnosis and treatment of polycystic ovary syndrome (PCOS). An elevated LH to FSH ratio implies:

• A higher likelihood of PCOS diagnosis, as studies have shown that women with PCOS tend to have higher LH levels and LH/FSH ratios compared to those without PCOS 2, 3, 4
• Poor ovulatory response, but better clinical pregnancy and live birth rates in women with PCOS after ovulation induction, particularly when the LH/FSH ratio is between 1 and 2 5
• No adverse effect on pregnancy rates in women with PCOS undergoing in vitro fertilization (IVF) with GnRH-agonist/antagonist protocols or in vitro maturation (IVM) treatments 6

Key Findings

• The ratio of LH/FSH ≥ 1 provides significant value in the diagnosis of PCOS 2
• An elevated LH/FSH ratio is associated with hyperandrogenism, insulin resistance, and obesity in women with PCOS 3, 4
• The LH/FSH ratio is not a characteristic attribute of all PCOS women, and its elevation is detected in a subpopulation of less than 50% of women with PCOS 4

Clinical Implications

• The LH/FSH ratio can be used as a diagnostic tool for PCOS, particularly in combination with other clinical and hormonal parameters 2, 3
• Women with PCOS and elevated LH/FSH ratios may require individualized treatment approaches, taking into account their specific hormonal and metabolic profiles 5, 6