hCG vs Gonadorelin half-life
hCG has an elimination half-life of about 30 h; Gonadorelin has about 18 min. hCG mimics LH and acts directly on the gonads, with a long half-life. Gonadorelin is synthetic GnRH that signals the pituitary to release LH and FSH, and it is cleared within minutes.
Side by side
| hCG | Gonadorelin | |
|---|---|---|
| Half-life | 30 h (range 23–36 h) | 18 min (range 10–40 min) |
| Route | SC / IM | SC / IV |
| Category | Reproductive & hormonal | Reproductive & hormonal |
| Evidence | Clinical | Clinical |
| Remaining after 24 hours | 57.4% | <0.01% |
| Remaining after 7 days | 2.06% | <0.01% |
| ~97% cleared (5 half-lives) | 6.3 days | 1.5 h |
| Steady state (4-5 half-lives) | 5 days to 6.3 days | 1.2 h to 1.5 h |
Single-dose decay
Share of one dose remaining over time, assuming first-order elimination. Dashed lines mark each half-life.
hCG (t½ 30 h) Gonadorelin (t½ 18 min)
At this scale Gonadorelin clears almost immediately. Zoomed in to its first five half-lives:
hCG (t½ 30 h) Gonadorelin (t½ 18 min)
hCG: Label: terminal half-life of roughly 1–1.5 days. Gonadorelin: Label: terminal half-life 10–40 minutes.
FAQ
Which lasts longer, hCG or Gonadorelin?
hCG lasts longer. Its half-life is about 30 h, versus 18 min for Gonadorelin, roughly 100 times longer.
How long do hCG and Gonadorelin stay in your system?
With first-order elimination, about 97% of a single dose is cleared after five half-lives: roughly 6.3 days for hCG and 1.5 h for Gonadorelin. Individual clearance varies.
How long until hCG and Gonadorelin reach steady state?
With consistent repeated dosing, levels approach steady state after 4 to 5 half-lives: about 5 days to 6.3 days for hCG, and 1.2 h to 1.5 h for Gonadorelin.
How reliable are these half-lives?
hCG: Clinical evidence. Gonadorelin: Clinical evidence. Anecdotal values are community estimates and may be far off.