Prostanoids, also known as eicosanoids, are a family of signaling molecules produced and secreted by various types of cells under both normal and pathological conditions. In the human body, these metabolites are excreted into body fluids such as plasma and urine. The precursors of prostanoids are 20-carbon polyunsaturated fatty acids (PUFAs) like arachidonic acid (C20:4), which are esterified in cell membrane phospholipids.