GROWTH HORMONE (GH):
Physiology & Deficiency:
For the last 60 years or so, growth hormone has been consistently and solely mentioned in the context of its skeletal effects. Over 60 years of research have been spent so far scrutinizing the impact of growth hormone on the final length of a limb. The verdict was out since the beginning in the sense that growth hormone is very important for physical growth. Kids with low growth hormone are usually shorter and pudgy looking. Children with excess growth hormone on the other hand grow taller and wider than most other people; if not treated they keep physically growing into adulthood. It has been my experience that how tall someone is a significant but minor component of how far one can go in life. No matter how important length is, it remains less influential than intelligence and socializing skills.
Having cleared the classic growth hormone role out of the way; what about other effects of growth hormone in a growing person? Having learned how efficient the human body is, I am forced to wonder if the bone growth effects of GH are the sole reason for this hormone’s existence. Without a doubt, there are a multitude of behavioral and physiologic effects of GH beside the classic role. This is going to be the focus of the rest of this section.
Relatively, very few studies are present in the literature about the other aspects of GH activity. One of the prominent physiologic functions of GH is related to building up proteins in muscle and the body’s internal organs including liver and heart and so forth. Behaviorally, children with known GH deficiency show similar intelligent quotient to other children. Yet, somehow they have problems in academic performance. Their problems do not seem to be related to the fact that they may be shorter than their peers. Learning seems to be more difficult when GH is absent or present in limited quantities. Disordered thinking is also frequently apparent. This goes to incomplete development of industriousness, a concept discussed in the chapter on early child development.
Acquisition of social skills seems to lag behind in the limited presence of GH. Many kids lag behind in making friends, verbally expressing their needs, negotiating their way to some ice cream or preventing another kid from stealing their toy. In addition, children with low GH levels have a higher tendency for anxiety and low mood as children and later in adulthood. These children may frequently appear ‘behaviorally inhibited’. They may also show a tendency for somatization – transferring mental frustration into physical pain and discomfort - consciously or unconsciously.
The interesting thing in this area is that children with low GH who are discovered and replaced early on, relatively catch up on many of the social skills. Earlier discovery of GH problems leads to near complete restoration of lost physical, mental and emotional components. Discovery and replacement later during childhood or in adulthood is usually still helpful but does not lead to complete reversal of the behavioral aspects. In particular, some studies show that the problems in social skills may persist to some degree throughout life despite late onset treatment. In fact, continuing treatment during adulthood may contribute to improvement in the social aspect but does not resolve the problem completely. This makes sense since certain skills are learned for example at a specific age through interaction with peers of the same age. Missing the window and replacing with the appropriate hormone(s) later in life, still falls short of providing the environmental stimulation necessary for the development of the skills.
Another note relates to the weight of growth hormone in the various problems discussed so far. Some of the observed problems with low GH may not be directly related to GH but rather to the impact of excessive stress which in turn lowers GH. Keep in mind that GH is only one of many hormonal, physiologic, genetic and environmental factors necessary for a complete child development. Replacing growth hormone in an isolated fashion without attending to the other components can only provide limited but necessary help.
Some kids however, can get lucky in the sense that even in the absence of adequate growth hormone, ample environmental stimulation can minimize the impact GH deficiency on social skills and somatization.
Lastly, there have been reports showing a direct impact of growth hormone in increasing the concentrations of the active thyroid hormone in the body, triiodothyronine.
Note for adults: Shorter, pudgy adults, who are sensitive, shy or withdrawn, are not so because they are short. On the contrary, the same problem that led them to grow up into shorter adults is the same problem that had a negative impact on their social outgoingness, and so forth. Replacement with growth hormone may not increase their height at this stage but can be instrumental as part of a therapy program aimed at reintroducing these folks to social skills they missed on learning earlier in life.
Note for insensitive children: In this case low GH may contribute to impulsive behavior, easily distraction, attention seeking from others (histrionic) and shorter attention span. These properties, while important in less sensitive children, rarely show up in the sensitive kids who also have low GH.
What about GH excess?
Slight GH excesses are usually a welcome addition for a growing child. Rarely however, extreme excesses (more than 2-3 folds the average) could present with continuing bone and muscle growth but otherwise behavioral problems that are in many ways
similar to those of GH deficiency.