Beta-lipotropin

Where it comes from

Made in

Pituitary corticotrophs

Sent out by

With ACTH, one for one; the corticotroph cuts little of it further

Acts on

• Fat cells (weakly)

What it does

• A carrier for beta-endorphin and beta-MSH, which other cells cut from it
• Circulates with ACTH and rises in Addison’s disease, Nelson’s syndrome and ectopic ACTH secretion ¹
• It is the main POMC product in human blood from this end of the molecule, outnumbering beta-endorphin by between three and thirty-eight to one ²

In medicine

• Once measured as a proxy for ACTH, and dropped: the old assays could not tell beta-lipotropin from the beta-endorphin cut out of it ²
• Two-site assays that separate the two exist, and showed that much of what earlier studies reported as circulating beta-endorphin was beta-lipotropin ²

Beyond the body’s own use

• There is no beta-lipotropin product and no trial of one; it is a precursor, and the pieces cut from it are what act
• Its name came from fat-mobilising activity in animal tissue, and in people that effect is weak and has never been shown to matter, which remains the open question about it ³
• It does matter as a measurement problem: any claim about blood beta-endorphin has to show the assay was not reading beta-lipotropin instead ²
• Levels rise in chronic kidney failure, which suggests the kidney clears it, and no clinical use has been made of that ¹