{Reference Type}: Journal Article {Title}: Sulfate: a neglected (but potentially highly relevant) anion. {Author}: den Bakker E;Smith DEC;Finken MJJ;Wamelink MMC;Salomons GS;van de Kamp JM;Bökenkamp A; {Journal}: Essays Biochem {Volume}: 0 {Issue}: 0 {Year}: 2024 Apr 19 {Factor}: 7.258 {DOI}: 10.1042/EBC20230097 {Abstract}: Sulfate is an important anion as sulfonation is essential in modulation of several compounds, such as exogens, polysaccharide chains of proteoglycans, cholesterol or cholesterol derivatives and tyrosine residues of several proteins. Sulfonation requires the presence of both the sulfate donor 3'-phosphoadenosine-5'-phosphosulfate (PAPS) and a sulfotransferase. Genetic disorders affecting sulfonation, associated with skeletal abnormalities, impaired neurological development and endocrinopathies, demonstrate the importance of sulfate. Yet sulfate is not measured in clinical practice. This review addresses sulfate metabolism and consequences of sulfonation defects, how to measure sulfate and why we should measure sulfate more often.