**7. Leptin in polycystic ovary syndrome (PCOS)**

PCOS is a heterogeneous disease, characterised by chronic oligo/an-ovulation, hyperandrogenism and polycystic ovaries on morphology. It is one of the most common endocrine disorders of women of reproductive age group affecting 5–10% of these women. It is also the most common cause of anovulatory infertility.

Since a vast majority of these patients are obese and have metabolic derangements, several studies have been conducted investigating the role of leptin in PCOS which have yielded conflicting results [1, 17].

It has been observed that the increased LH levels seen in PCOS patients are also associated with increased leptin levels [45]. Since nearly half of these women present with obesity, hyperleptinemia is a common association in PCOS. Several studies have elucidated elevated levels of leptin in PCOS [46, 47]. Others have linked leptin with the insulin resistance seen in PCOS [48]. Leptin has also been associated with the pro-inflammatory and hyperandrogenic state seen in PCOS [49].

Since hyperleptinemia is observed in several clinical manifestations associated with PCOS, it may be speculated that leptin may have a role in the etiopathogenesis of the disease. However, studies directly demonstrating leptin as one of causative factors of PCOS are still sparse.
