The largest study of its kind, designed to track the development of Creutzfeldt-Jakob disease in people who received human growth hormone from cadavers, has found that the vast majority of those who received the hormone did not contract the fatal condition. However, some recipients (26 out of approximately 7,700) did develop the disease.
A larger number (59) died from adrenal crisis, a sometimes-fatal complication that can be prevented if it is recognized and treated promptly.
Adrenal crisis does not affect all patients who require growth hormone, but may occur in a subgroup of patients whose pituitary gland fails to make not only growth hormone but also the hormone needed to regulate the adrenal glands.
Human growth hormone is now manufactured synthetically, and the synthetic form does not transmit Creutzfeldt-Jakob Disease (CJD). The study tracks individuals who received cadaver-derived human growth hormone, to determine their risk of developing CJD and to observe their health status.
The federal study's findings appear in the April Journal of Pediatrics. It was conducted by scientists at several agencies in the U.S. Department of Health and Human Services (HHS). At the National Institutes of Health, researchers from the National Institute of Child Health and Human Development, the National Institute of Neurological Disorders and Stroke, and the National Institute of Diabetes and Digestive and Kidney Diseases, took part in the study. Researchers from two other HHS agencies, the U.S. Food and Drug Administration and the Centers for Disease Control and Prevention, also participated, as did the research corporation Westat.
Growth hormone deficiency results from a failure of the pituitary gland to make sufficient amounts of the hormone, explained the study's principal author, James L. Mills, M.D., chief of the Pediatric Epidemiology Section of the National Institute of Child Health and Human Development (NICHD). Individuals who lack growth hormone are abnormally short. Growth hormone is also needed to maintain normal blood sugar; its absence may result in potentially fatal drops in blood sugar (hypoglycemia).
According to the 1994 Utah Growth Hormone Study, growth hormone deficiency occurs in 1 out of every 3,480 children.
Patients who can't make their own growth hormone may also lack other hormones produced by the pituitary, including the hormone that regulates the adrenal glands, Dr. Mills added. The adrenals, located atop the kidneys, secrete cortisol, a hormone that protects the body in stressful situations. In times of illness or other stress, individuals who lack adrenal hormones are subject to an adrenal crisis — a potentially fatal loss of salts and fluids. However, an adrenal crisis can be treated and sometimes prevented with the drug hydrocortisone. Treatment for an adrenal crisis may be given in either tablet form or by injection. In addition to those whose pituitaries fail to make the proper hormone to regulate the adrenal glands, adrenal crisis may also result from other medical conditions.
From 1963 to 1985, the National Hormone and Pituitary Program (NHPP) supplied human growth hormone to individuals who needed it. Because synthetic human growth hormone wasn't available at the time, it was necessary to extract the hormone from the pituitaries of cadavers. But in 1985, researchers learned that the cadaver-derived hormone could transmit CJD, a fatal disease affecting the brain, and halted distribution of the hormone. Information for people treated with growth hormone from the NHPP is available at http://www.niddk.nih.gov/health/endo/pubs/creutz/updatecomp.htm#5.
The current federal study began in 1985. Of the approximately 7,700 people in the United States who received cadaver-derived hormone from the NHPP, 26 died of CJD. It is also possible that more deaths from CJD will occur in this group in the future. Dr. Mills said some studies indicate that CJD may take 30 years or more to develop.
The study authors noted that patients who lacked only growth hormone and had no underlying medical problem but produced normal amounts of other pituitary hormones had a death rate that was comparable to what would be expected in a general population of people in the same age group. However, individuals who lost the ability to produce other pituitary hormones — often because of tumors or brain injury — had higher death rates.
Of the approximately 7,700 people who received the hormone from the NHPP, 6,107 took part in the current study. Of these, 1,419 required therapy to replace their adrenal hormones. There were 59 deaths from adrenal crisis in this group. Many of the circumstances surrounding the individuals' deaths are not known, Dr. Mills said. Some patients were simply found dead. A possible factor in these deaths could be the age of those who died, Dr. Mills added. Many were adolescents and young adults, an age group that may tend to ignore health concerns and take risks.
In addition, a major symptom of an adrenal crisis, vomiting, might also interfere with successful treatment. The study authors wrote that the vomiting might make it impossible to keep the hydrocortisone tablets in the stomach long enough for them to take effect.
Dr. Mills said that one option patients and their physicians might consider is to have a needle and syringe available for emergencies, so that the patient or a family member might inject the hydrocortisone whenever vomiting occurs.
He added that many of the deaths occurred after relatively mild illnesses, such as colds and pneumonia. Even such minor stresses require patients to take higher doses of hydrocortisone.
According to a health alert by the National Institute of Diabetes and Digestive and Kidney Diseases, symptoms of a cortisol shortage are feeling weak, feeling tired all the time, feeling sick to one's stomach, vomiting, no appetite, and weight loss. "When someone with adrenal gland problems has weakness, nausea, or vomiting, that person needs immediate emergency treatment to prevent adrenal crisis and possible death." The health alert is available at http://www.niddk.nih.gov/health/endo/pubs/creutz/alert.htm. The study authors wrote: "Our data underscore the need to initiate therapy promptly: of the 35 subjects found dead or comatose by families or friends, 30 (86%) probably died from unrecognized or inadequately treated adrenal insufficiency."
Other deaths resulted from problems not associated with pituitary hormone deficiencies. Many children died from the underlying conditions, such as brain tumors, that caused them to be growth hormone deficient. Similarly, there were 20 deaths from seizures among patients who did not appear to have adrenal insufficiency. Dr. Mills explained that these seizure deaths might have resulted from complications of brain tumors or brain injury.
Two study participants died of colon cancer. However, the authors wrote, these cases did not appear to be related to the use of growth hormone, despite the results from a smaller British study suggesting that growth hormone recipients had an increased risk of death from colon cancer. One patient from the current study had a hereditary form of polyposis, which increases the risk for colon cancer.
"The second patient had received radiation treatment for a brain tumor, which may have had an influence on the development of colon cancer," Dr. Mills said. "These results do not support the earlier study's finding that growth hormone was associated with an increased risk of death from colon cancer."