Can IGF 1 be tested reliably?

[Kracken]

I'm using CJC-1295/IPA and not any HGH. My understanding is that GH is released in pulses mostly as I sleep. The HGH converts to IGF 1. So does IGF 1 vary during a 24 hour period? If so, is there any point to testing it? If it changes during the day how can I get a meaningful result?

 

[james13]

IGF‑1 does vary a little over 24 hours, but the swings are small compared with GH pulses, so a single properly timed IGF‑1 test is still meaningful. GH is secreted in sharp pulses, with a major peak around deep sleep and very low levels between bursts. Circulating IGF‑1 is made mainly in the liver under GH control and is released in a much more tonic fashion, acting as an integrator of average GH exposure over days rather than minutes.

But to add to a little confusion, this is serum IGF-1, not tissue IGF-1. Serum IGF‑1 is biologically active and can act on muscle, but most of the hypertrophy‑relevant signaling in muscle is driven by IGF‑1 produced locally within the muscle itself rather than by the circulating pool.

To answer your question, yes, serum IGF-1 is relevant (enough).

 

[Kracken]

Great answer and explanation, thank you!