Editing Endocrinology (section)

=== Hormones ===
Griffin and Ojeda identify three different classes of hormones based on their chemical composition:<ref>{{cite book |author=Ojeda, Sergio R.|author2=Griffin, James Bennett |title=Textbook of endocrine physiology |url=https://archive.org/details/textbookofendocr00oxfo|url-access=registration|publisher=Oxford University Press |location=Oxford [Oxfordshire] |date=2000 |edition=4th |isbn=978-0-19-513541-1 }}</ref>

====Amines====
{{multiple image
| footer = Examples of '''amine hormones'''
| total_width = 270
| image1 = Norepinephrine structure with descriptor.svg
| caption1 = [[Norepinephrine]]
| image2 = Triiodothyronine.svg
| caption2 = [[Triiodothyronine]]
}}
Amines, such as [[norepinephrine]], [[epinephrine]], and [[dopamine]] ([[catecholamines]]), are derived from single [[amino acid]]s, in this case tyrosine. [[Thyroid]] hormones such as [[Triiodothyronine|3,5,3'-triiodothyronine]] (T3) and [[Levothyroxine|3,5,3',5'-tetraiodothyronine]] (thyroxine, T4) make up a subset of this class because they derive from the combination of two iodinated tyrosine amino acid residues.<ref>{{Cite journal |last1=Carvalho |first1=Denise P. |last2=Dupuy |first2=Corinne |date=2017-12-15 |title=Thyroid hormone biosynthesis and release |url=https://www.sciencedirect.com/science/article/pii/S0303720717300515 |journal=Molecular and Cellular Endocrinology |series=A century of thyroid hormone research - Vol. I: The expanded thyroid hormone network: novel metabolites and modes of action |volume=458 |pages=6–15 |doi=10.1016/j.mce.2017.01.038 |pmid=28153798 |s2cid=31150531 |issn=0303-7207}}</ref>

====Peptide and protein====
[[Peptide hormones]] and protein hormones consist of three (in the case of [[thyrotropin-releasing hormone]]) to more than 200 (in the case of [[follicle-stimulating hormone]]) amino acid residues and can have a molecular mass as large as 31,000 grams per mole. All hormones secreted by the pituitary gland are peptide hormones, as are [[leptin]] from adipocytes, [[ghrelin]] from the stomach, and [[insulin]] from the [[pancreas]].{{cn|date=May 2022}}

====Steroid====
{{multiple image
| footer = Examples of '''steroid hormones'''
| total_width = 270
| image1 = Cortisol2.svg
| caption1 = [[Cortisol]]
| image2 = Cholecalciferol.svg
| caption2 = [[Cholecalciferol|Vitamin D<sub>3</sub>]]
}}
[[Steroid hormones]] are converted from their parent compound, [[cholesterol]]. [[Mammal]]ian steroid hormones can be grouped into five groups by the receptors to which they bind: [[glucocorticoid]]s, [[mineralocorticoid]]s, [[androgen]]s, [[estrogen]]s, and [[progestogen]]s. Some forms of [[vitamin D]], such as [[calcitriol]], are steroid-like and bind to homologous receptors, but lack the characteristic fused ring structure of true steroids.