LEP and male infertility: By reviewing the full text rigorously, 58 articles were eliminated, including 7 references without sufficient information, 5 reduplicated studies, 12 studies conducted in nonhuman tissues, including materials from animals, such as pigs or rats, 4 studies which detected serum leptin concentrations with polymerase chain reaction (PCR), immunohistochemistry (IHC), and microarray, and 30 references which were not related to leptin and male infertility.