GH + AI Increases Height in Pubertal Patients
Or in other words, control estrogen and you can increase height. But what about the testosterone action fusing growth plates?
Results from three prospective randomised controlled trials using potent third-generation aromatase inhibitors have recently been published. These studies all show that treatment with the aromatase inhibitors letrozole and anastrozole effectively delays bone maturation and increases predicted adult height in boys with constitutional delay of growth and puberty (CDGP), idiopathic short stature and growth hormone deficiency.
Hold the phone… really?
3 separate groups used 1mg of anastrozole for 12 months, 24 months, and 36 months respectively. Linear growth was comparable between the groups: net increase in predicted adult height of 2.2cm at 12 months, 4.5cm at 24 months, and 6.7cm at 36 months. This is to be compared with just a 1-cm gain in the placebo group. Estradiol concentrations increased less in the anastrozole group compared with placebo group, with no significant differences in the speed of virilization and no real changes between the groups on glucose and lipids.
The dose of 1mg per week is notable – this is roughly the AI dose in a TRT dose of testosterone, which tends to range between 0.5mg-1mg per week from my personal experience. There were no adverse effects that can be tied to taking the drug. Anastrozole at this dose is generally well tolerated and this group of adolescents (average age of 13.8) is in line with that expectation.
As it goes for height, should this be combined with GH? GH adds height through increased height velocity, speeding growth up prior to plates closing. By keeping the plates open using an AI, I see a lot more value than using just either compound by themselves. And the data backs it up.
Use of AI combined with GH achieved a mean net height gain of 7.3cm. The only thing you need to keep in mind is the age of the patients that achieved this was on average 11.66 years old. Which brings us back to my original GH article saying that an early intervention age is key. Still though, given the availability of MK677 and anastrozole, I couldn’t or wouldn’t blame a late teen for trying to eek out the last half an inch of growth.
The researchers do note that they consider the end of linear growth to be a bone age of at least 16 years old and a growth velocity of less than 2cm/year. The bone age is the predictor here for if this treatment will be effective and is usually correlated with biological age, but not always exactly – for example, a 16 year old may have a bone age of 15, therefore GH & AI treatment may still yet be effective. In males, epiphyseal fusion (when your growth plates close and you’re SOL) range between 14 - 19 (race offers some variability), 12 - 16 for ladies. If you’re outside of these ranges this treatment is unlikely to be effective for you.
Glad to have explored this topic, which I hope has answered a couple of follow up questions I had from our members.