Gonadorelin Dosing
For diagnostic testing of pituitary function, gonadorelin is administered as a single intravenous dose of 80-100 mcg, with gonadotropin levels measured at baseline and 30-60 minutes post-injection. 1, 2
Diagnostic Testing Protocol
Standard diagnostic dose:
- 80-100 mcg gonadorelin administered as a single intravenous injection 1, 2
- Measure LH and FSH at baseline (time 0) and at 30-60 minutes post-injection to capture peak gonadotropin response 2
- A typical gonadotropin release with peak LH levels at 30-60 minutes indicates normal pituitary responsiveness 2
Two-step diagnostic testing (when indicated):
- First dose: 80 mcg gonadorelin IV 2
- Second dose: 80 mcg gonadorelin IV at 120 minutes after the first dose 2
- This protocol assesses pituitary reserve and priming response, though the second peak may not be significantly higher than the first 2
Therapeutic Applications
For induction of spermatogenesis in hypogonadotropic hypogonadism:
- Pulsatile subcutaneous administration: 5-20 mcg every 120 minutes (every 2 hours) via pump 3
- This mimics physiologic GnRH pulsatility and is highly effective for restoring fertility in men with hypothalamic disorders 3
- Treatment continues until sperm appears in ejaculate or pregnancy is achieved 3
For ovarian function suppression (using GnRH agonists like leuprolide, not native gonadorelin):
- Leuprolide 3.75-7.5 mg IM every 4 weeks OR 11.25-22.5 mg IM every 12 weeks 4, 5
- Preferred timing is 10-14 days prior to cyclophosphamide administration when used for fertility preservation 4
- Goserelin 3.6 mg SC every 4 weeks OR 10.8 mg SC every 12 weeks is an alternative 4
Veterinary Use (Not for Human Application)
The FDA-approved veterinary formulation uses 100 mcg gonadorelin (as acetate or diacetate salt) administered intramuscularly for synchronization of estrous cycles in cattle 1. This dosing is specific to veterinary medicine and should not be extrapolated to human use.
Key Clinical Considerations
Diagnostic testing interpretation:
- Patients with congenital gonadotropin deficiency typically show subnormal LH response to initial GnRH agonist testing 6
- Repetitive intermittent dosing (every 4-5 days) can normalize the LH response within 2 weeks in congenitally deficient patients, helping distinguish hypothalamic from pituitary causes 6
- The pituitary response does not immediately depend on basal gonadotropin levels but reflects the severity of hypothalamic-pituitary dysfunction 2
Therapeutic efficacy:
- Both pulsatile GnRH (gonadorelin) and exogenous gonadotropin therapy achieve high efficacy for inducing spermatogenesis in hypogonadotropic men, with sperm appearing in 30 of 33 treated patients in one series 3
- Pregnancies can occur even with sperm counts below normal range 3
Common pitfalls:
- Do not confuse native gonadorelin (used diagnostically or in pulsatile therapy) with long-acting GnRH agonists like leuprolide, which have entirely different dosing regimens and mechanisms 4
- Single-dose or intermittent gonadorelin administration for therapeutic purposes is generally ineffective; continuous pulsatile delivery is required for sustained gonadotropin stimulation 3, 7
- Constant infusion of GnRH agonists (not native gonadorelin) paradoxically suppresses rather than stimulates gonadotropin secretion through receptor downregulation 7, 8