Sermorelin research: pediatric and adult trials

The older men’s blood tests

Corpas and colleagues studied healthy older men for 14 days. Their average age was 68 years; the researchers compared growth hormone and IGF-1 readings with those of younger men. At the larger tested amount, the older men's hormone parameters no longer differed significantly from the younger group's. Fasting glucose did not change.

That younger comparison gives the result its pull, at least for me. Something that had declined with age could be shifted toward the younger comparison. But the measured achievement was a change in hormone output and IGF-1. Whether those men became stronger, more capable or healthier over years remained another question. The study amounts explain the treatment conditions without making them a personal regimen.

A later study of single nightly GHRH(1-29) injections in healthy elderly men adds a useful complication: overnight growth hormone rose, while pulse frequency and IGF-1 did not. That divergence weakens the “restoring youth” story for me. Frequency, timing and the outcome being sampled all deserve attention.

Sermorelin mechanism of action

The GHRH receptor on pituitary growth hormone-producing cells starts a cellular signaling pathway involving cAMP and protein kinase A. That activity promotes growth hormone synthesis and release. Sermorelin uses the active 1-29 fragment of the body's longer GHRH signal.

The pituitary releases growth hormone in pulses. Feedback from IGF-1 and somatostatin still operates during Sermorelin stimulation. I see why this physiology appealed to the author of the 2006 editorial favoring Sermorelin for adult-onset growth hormone insufficiency. It offers a coherent rationale for investigation. Establishing comparative long-term benefit and safety requires trials beyond that rationale.

There is also a sobering result from children with partial growth hormone deficiency. During continuous GHRH(1-29) infusion, an early increase in growth hormone was followed by declining secretion; one child's secretion was fully suppressed. The researchers considered several explanations, including antibodies and reduced receptor responsiveness. Choosing a single explanation would give me more certainty than this small study supports. It does show how much the pattern of exposure can matter.

Childhood growth

In the multicenter trial of prepubertal children with growth hormone deficiency, once-daily subcutaneous Sermorelin accelerated first-year height velocity from about 4.1 cm/year to roughly 7-8 cm/year, without excessive IGF-1 generation. Here the outcome has an appealing directness: the children grew faster.

The review of pediatric diagnosis and treatment places that result in Sermorelin's former clinical role. Short stature and deficient growth hormone release were specific medical problems. The result satisfies my demand for a direct connection between the problem and the outcome. Adult claims about vitality or aging need an equally clear meeting of question and result.

The adult outcomes still worth testing

The debate has room for both the physiological argument and Blackman’s caution about growth hormone secretagogues for aging. His 2008 editorial judged the evidence insufficient to justify that broad use. The adult trial I still want would follow daily function and harms over years.

A strength test gives that question a more concrete shape than the word “vitality.” So would reliable evidence about sleep, physical performance or illness over a long follow-up. The present studies leave that larger adult case open.

Some enticing results nearby come from a different medicine: the 20-week tesamorelin trial in older adults with and without mild cognitive impairment reported favorable cognition and body-fat findings. Its 152 participants included 66 with mild cognitive impairment. Those results strengthen the tesamorelin case, in my judgment; the comparison page explains why transferring them to Sermorelin spends evidence twice.