Short answer: It can. Somatropin labels say growth hormone treatment can uncover or worsen central (pituitary) hypothyroidism, and can lower cortisol, so people on hydrocortisone-type replacement may need a higher dose. The labels call for periodic thyroid tests. They also say women on oral estrogen may need more growth hormone, and that insulin or other diabetes medicine doses may need adjusting.
The Genotropin label says that in people with growth hormone deficiency, central (secondary) hypothyroidism may first become evident or worsen during somatropin treatment. Central hypothyroidism means the pituitary is not sending enough signal to the thyroid. The label says patients should have periodic thyroid function tests, and that thyroid hormone replacement should be started or adjusted when needed. It also notes that untreated low thyroid may blunt the response to growth hormone, and lists central hypothyroidism among the serious reactions seen with somatropin.
A 2011 review of the research found that in adults with pituitary disease, growth hormone replacement has been reported to uncover central hypothyroidism in 36 to 47% of people whose thyroid tests looked normal before, needing thyroxine. The review says the risk is highest with organic pituitary disease or several pituitary hormone deficiencies, and that some studies found the changes short-lived.
An enzyme called 11-beta-HSD1 turns inactive cortisone into active cortisol in the liver and fat. The labels explain that growth hormone blocks this enzyme, so starting somatropin can lower cortisol levels. Two things follow, according to the label:
In children, the label adds that high glucocorticoid doses can reduce the growth effect of somatropin, so both doses are adjusted together.
| Medicine | What the label says |
|---|---|
| Oral estrogen | Women on oral estrogen may need a larger somatropin dose; Norditropin says oral estrogen may reduce the IGF-1 response |
| Insulin and other diabetes medicines | Doses may need adjusting when somatropin is started |
| Medicines broken down by liver CYP450 enzymes (such as corticosteroids, sex steroids, seizure medicines, cyclosporine) | Somatropin may change how fast they are cleared; careful monitoring is advised |
See estrogen and thyroid medicine for how oral estrogen itself changes thyroid hormone needs.
Because these effects show up on blood tests, the timing of thyroid, cortisol and IGF-1 checks is set by the prescriber, usually an endocrinologist. Dose Track can log somatropin doses next to levothyroxine or hydrocortisone doses and lab dates, so a change in one can be lined up against the others.
Read more on Dose Track: Genotropin side effects · Norditropin side effects · Human growth hormone · Hypothyroidism · IGF-1