My 17-year-old daughter asks me every now and then, what was I thinking when we got a German Shepherd puppy the same time I found out I was pregnant with her. She’s the youngest of four children. She tends to bring up the new-baby-new-dog question after watching videos of our chaotic household. There was a time when there was an infant girl, twin two-year-olds (boy and girl), a four-year-old boy, a 3-year-old Golden Retriever, an African water frog (age undetermined) and, yes, the German Shepherd puppy.
I was thinking about this lately, not so much for the obvious questions (What was I thinking?) but more about hormones, and in particular growth hormone. That's because the latest guidelines just landed in my inbox, which will certainly help a lot of parents make decisions. But it helps to understand some basic biology of the hormone.
We humans are unique in the way we pace our growth. Unlike other mammals, we hit the gas pedal right before birth, plumping up ferociously in the last month. We gently press on the brakes as we hit the outside world. We grow but a lot slower. We lull into a drawn-out childhood. Think about it: our pets have reached their final size and are making their own babies when most of us are still on tippy-toes trying to sip from a water fountain.
If, say, you get a German shepherd puppy about the same time you have a baby (as I did), you’ll notice that by six months, your baby fits snugly in a Snugli. Your dog won’t. Soon enough, Dexter, our German Shepherd, was towering over all the kids.
Anthropologists have theorized that we have a prolonged youth—compared to our mammalian cousins—in order to acquire greater chunks of knowledge to pass along to the next generation.
Endocrinologists see this through the prism of hormones. The difference between your little human and your little dog is, in part, the timing of these chemical substances. When your dog is about six months and your child about 12 years, one brain gland (the hypothalamus) tells another one (the pituitary) to dial up growth hormone output. Linear growth, scientists discovered, depends not just on growth hormone but on sex hormones too. Growth hormone also prompts the release of other helper hormones that in turn stretch bones and muscles. A child who isn’t growing may lack growth hormone. Or he could have the right amount of it, but lack other helper hormones. Or he could have all the right amounts but has signaling issues. His body isn’t passing along the messages correctly.
Some people are short because they just are. They have all adequate amounts of hormones, but never reach average heights. That’s me. I was always the smallest one in the class. Now, at not quite 5’2”, I’m the shortest in the family.
When I was younger, no one thought whether something should or could be done to boost height among those without a diagnosable disorder. The synthesis of lab-made growth hormone in 1985 changed the whole decision-making process.
Just last week, a panel of experts considered the most up-to-date information and generated a new set of guidelines. The full report is published in Hormone Research in Paediatrics.
Generally, the doctors say that if a child is shown to lack growth hormone, he should be on treatment. It’s not just about getting taller but growth hormone is also needed for the heart and bones. Growth hormone does lots of things to maintain health and development. It’s not just for growing.
If a child does not have a proven lack of hormone, further tests are needed. He, or she, may lack other enzymes in the pathway. Or there could be other metabolic problems. That’s when you need a specialist—a pediatric endocrinologist—to figure out the best remedy.
Here’s the concern. Every drug has side effects. The kids who started taking growth hormone in 1985 are only in their 40s, so doctors still don’t know the long term repercussions—if any. The doctors in this panel worry about parents who want to give their children growth hormone because they think being taller boosts self-esteem. Not always.
Adda Grimberg, a pediatric endocrinologist at the Children’s Hospital of Phildelphia, was one of six pediatric endocrinologists that issued the new guidelines. As she was quoted in a press release, “If you have growth hormone deficiency, there are health reasons for wanting to replace growth hormone, and it’s not just about height. It’s not controversial and you treat. When you have healthy short kids who have idiopathic short stature and want to be taller, however, you are exposing them to unknown risks down the road. That is an ethical consideration.”
As for my growing family, the big dogs are no longer with us, nor the African Water frog. We’ve downsized to a 10-pound Havanese. She’ll be eight-years-old soon and we hope she’ll be with us a lot longer. When it comes to dogs and size, as most dog-owners know, little dogs tend to have longer lifespans. No one knows why. One hormone theory is that bigger dogs have more of a hormone called IGF-1, short for insulin-growth like factor-1. A few studies on humans and dogs have suggested that high levels of this hormone are related to an increased risk of cancer and heart disease.
As for the rest of us, my house is a lot less chaotic. Kids are now 17, 21, 21, and 23. Maybe it’s time for another puppy.
Horm Res Paediatr. 2016;86(6):361-397. doi: 10.1159/000452150. Epub 2016 Nov 25.
Guidelines for Growth Hormone and Insulin-Like Growth Factor-I Treatment in Children and Adolescents: Growth Hormone Deficiency, Idiopathic Short Stature, and Primary Insulin-Like Growth Factor-I Deficiency.
Grimberg A1, DiVall SA, Polychronakos C, Allen DB, Cohen LE, Quintos JB, Rossi WC, Feudtner C, Murad MH; Drug and Therapeutics Committee and Ethics Committee of the Pediatric Endocrine Society.