Basal growth hormone (GH) levels of less than 2.5 µg/liter and glucose-suppressed GH levels of less than one µg/liter along with normal levels of IGF-1 (a mediator of GH's actions) have traditionally been considered desirable treatment goals for acromegaly patients but whether the risks of cardiovascular disease were minimized by achievement of such treatment goals was not known. Two separate groups of researchers have re-examined how successful treatment of acromegaly would impact on cardiovascular risks.
In the first study, Dr. Ian Holdaway and researchers at Aukland Hospital in New Zealand followed 208 acromegalic patients between 1964 and 2000 for an average of 13 years to understand mortality risks associated with acromegaly. During the follow-up, seventy-two patients (35 percent) died at an average age of 61. Researchers found that those who died had a higher prevalence of hypertension and diabetes and were more likely to suffer from osteoarthritis and hypopituitarism. The researchers found that patients who had a final GH level below two µg/liter were more likely to have survived. In addition, surviving patients had a lower serum IGF-1 score at the last follow-up appointment when compared with the deceased. Patients who achieved GH levels of less than 1 ?g/liter and who had normal IGF-1 levels had survival rates similar to the general population.
"In general, the death rates appear to increase among patients who have been treated for acromegaly. Additionally, these patients seem to be dying from detectable conditions such as cardiovascular disease," explains Dr. Holdaway, the lead investigator on the study and an endocrinologist at Auckland University School of Medicine. "Fifty percent of the deceased subjects in our study died from cardiovascular events, which is much higher than we expected. It is clear from our findings that acromegaly puts patients at an increased risk for serious health conditions, such as cardiovascular disease. As a result, these patients must be closely monitored for this and other related conditions."
In a second study, Dr. Omar Serri and his colleagues at the University of Montreal studied postoperative patients with acromegaly and discovered that even with glucose-suppressed GH levels less than 1 µg/liter, they may still be at an increased risk for developing conditions that could lead to diabetes and hypertension. The researchers examined 53 patients after transphenoidal surgery for acromegaly and 20 healthy subjects matched for age, sex and body mass index. Subjects were evaluated using a series of tests that measured plasma glucose, GH, plasma IGF-1 and blood pressure.
Dr. Serri's results suggest that even GH measurements of 1 µg/liter following glucose load, which is commonly considered to be a desired level in acromegaly patients, may not be sufficient to define a biochemical remission of acromegaly.
"Our findings indicate that a GH measurement of 1 µg/liter post-glucose load fails to identify a significant proportion of postoperative acromegalic patients who still suffer from the disease, which is defined by elevated levels of IGF-1. Normal serum IGF-1 is a more reliable criterion of remission of acromegaly," notes Dr. Serri, the lead investigator on the second study and an endocrinologist at the University of Montreal.
"This is important because patients who have previously been considered to be in remission from acromegaly may still be at risk for other health complications, such as diabetes and hypertension," Dr. Serri explains.
JCEM is one of four journals published by The Endocrine Society. Founded in 1916, The Endocrine Society is the world's oldest, largest, and most active organization devoted to research on hormones, and the clinical practice of endocrinology. Endocrinologists are specially trained doctors who diagnose, treat and conduct basic and clinical research on complex hormonal disorders such as diabetes, thyroid disease, osteoporosis, obesity, hypertension, cholesterol and reproductive disorders. Today, The Endocrine Society's membership consists of over 11,000 scientists, physicians, educators, nurses and students, in more than 80 countries. Together, these members represent all basic, applied, and clinical interests in endocrinology. The Endocrine Society is based in Chevy Chase, Maryland. To learn more about the Society, and the field of endocrinology, visit the Society's web site at www.endo-society.org
Journal
The Journal of Clinical Endocrinology & Metabolism