GDF-15

A stress-responsive cytokine that rises with cellular and mitochondrial stress, tracks mortality risk across many conditions, and drives appetite suppression through a brainstem receptor.

What it signals

GDF-15 is released by cells under stress: mitochondrial dysfunction, tissue injury, inflammation, hypoxia and some drug exposures all raise it. Because so many processes converge on it, it behaves less like a specific diagnostic and more like a general alarm level.

It rises steadily with age and is one of the more consistent circulating correlates of biological aging, frailty and multimorbidity in population studies.

The appetite connection

In 2017 GDF-15 was shown to act through GFRAL, a receptor restricted to a small region of the brainstem, to reduce food intake. That explains the loss of appetite seen in advanced cancer and in some acute illness, and it made GDF-15 an obesity drug target in its own right.

It is also part of why metformin does what it does. Metformin raises circulating GDF-15, and in mouse work its weight lowering effect requires GFRAL signaling.

How to use the number

As a research and risk stratification marker, GDF-15 is impressive. As a personal test it is limited: there is no established treatment threshold, no intervention proven to lower it for benefit, and no reference range you should act on directly.

It belongs in the category of markers worth watching in the literature rather than chasing in your own blood.

GDF-15 is not a marker we recommend, because it has no actionable threshold outside research.

References

  1. Emmerson PJ, et al. The metabolic effects of GDF15 are mediated by the orphan receptor GFRAL. Nat Med. 2017.
  2. Coll AP, et al. GDF15 mediates the effects of metformin on body weight and energy balance. Nature. 2020.
  3. Wiklund FE, et al. Macrophage inhibitory cytokine-1 (MIC-1/GDF15): a new marker of all-cause mortality. Aging Cell. 2010.