Sermorelin for Growth Hormone Deficiency
Sermorelin (GHRH 1-29) is administered at 30 mcg/kg/day subcutaneously at bedtime for treating children with idiopathic growth hormone deficiency, though it is less effective than recombinant growth hormone and is not a first-line therapy. 1, 2
Diagnostic Use
Sermorelin serves primarily as a diagnostic tool rather than a therapeutic agent:
- Intravenous sermorelin 1 mcg/kg bodyweight provides a rapid and relatively specific test for diagnosing growth hormone deficiency, with fewer false positives compared to other provocative tests 1
- A normal GH response to sermorelin cannot exclude hypothalamic GH deficiency, requiring confirmation with subnormal responses to other provocative tests 1
- Peak serum GH response above 30 mU/L during IV GHRH testing predicts good growth response to therapy, though lower peaks do not preclude therapeutic benefit 3
Therapeutic Dosing and Administration
When used therapeutically in children with idiopathic GH deficiency:
- Dose: 30 mcg/kg/day subcutaneously at bedtime 1, 2
- The bedtime administration mimics physiological GH secretion patterns 4
- Treatment duration studied ranges from 6-36 months with sustained effects 1, 2
Expected Outcomes
Growth response data from clinical trials:
- Mean height velocity increased from 4.1 cm/year at baseline to 8.0 cm/year at 6 months and 7.2 cm/year at 12 months 2
- 74% of children showed good response at 6 months 2
- Catch-up growth occurred in the majority of GH-deficient children treated 1
- Slow-growing, shorter children with delayed bone and height age demonstrate the best response 1
- Bone age progression remained appropriate (ratio of bone age to height age change = 1.04 at 12 months) 2
Comparative Effectiveness
Sermorelin is less effective than recombinant growth hormone (somatropin):
- Height velocity increases with sermorelin 30 mcg/kg/day (given as continuous infusion or 3 divided doses) were inferior to once-daily somatropin 30 mcg/kg/day 1
- In children previously treated with human GH, height velocity on hGH correlated with that on GHRH, but 4 of 14 patients showed growth deceleration with GHRH for unknown reasons 3
Safety Profile
Sermorelin demonstrates good tolerability:
- Most common adverse events: transient facial flushing and pain at injection site 1, 2
- No adverse changes in biochemical or hormonal analyses 2
- No excessive IGF-1 generation or changes in fasting glucose 2
- Anti-GHRH antibodies developed in 78% of patients (14 of 18) but did not adversely affect growth or GH responses 3
- No priming or desensitization effects observed with continued therapy 3
Clinical Context and Limitations
Current clinical practice strongly favors recombinant GH over sermorelin:
- Recombinant GH (0.045-0.05 mg/kg/day subcutaneously) is the established standard for treating GH deficiency in children with CKD and other conditions 5
- The effect of long-term sermorelin treatment on final adult height remains undetermined 1
- Sermorelin requires intact pituitary function to be effective, limiting its use to hypothalamic causes of GH deficiency 1
Monitoring Requirements
If sermorelin is used therapeutically, monitoring should parallel GH therapy protocols:
- Clinic visits every 3-6 months to assess height velocity, pubertal development, and skeletal maturation 5, 4
- Monitor IGF-1 levels, glucose metabolism, thyroid function (TSH, free T4), calcium, phosphate, and PTH 5, 6, 4
- Baseline fundoscopy before initiation to screen for contraindications 4
Key Clinical Caveat
Sermorelin is not FDA-approved or guideline-recommended as first-line therapy for growth hormone deficiency. The evidence base consists primarily of older studies from the 1980s-1990s, and modern clinical practice guidelines universally recommend recombinant GH as the standard treatment 5. Sermorelin may have limited utility in select cases where hypothalamic GH deficiency is confirmed and pituitary function is intact, but this represents an uncommon clinical scenario.