Prior studies have shown that interferon, a naturally
occurring cytokine used to treat chronic hepatitis
C virus (HCV) infection, has multiple but contradictory effects on secretion
of pituitary hormones. The pituitary is the "master gland" in the brain
that produces several hormones which control the activity of endocrine glands
throughout the body.
The
growth hormone (GH) is a protein hormone released from the anterior pituitary
gland under the control of the hypothalamus.
To
further explore this topic, German researchers prospectively assessed basal and
stimulated pituitary hormone secretion in 21 chronic hepatitis C patients before
and during antiviral therapy with pegylated
interferon alpha plus either ribavirin or the chemically related agent levovirin.
Baseline and stimulated secretion of growth hormone (GH), cortisol, luteinizing
hormone (LH), follicle-stimulating hormone (FSH), prolactin, and thyroid-stimulating
hormone (TSH) were measured using standard pituitary function tests before therapy
in all 21 participants and during therapy in 17 patients.
Results
•
Before therapy, 17 patients (81%) had severe GH insufficiency and 9 of these
had low insulin-like growth factor-1 (IGF-1) concentrations.
•
Basal and stimulated GH concentrations increased significantly during therapy,
reducing the number of patients with severe GH insufficiency to 4; IGF-1 levels,
however, remained low.
•
Basal prolactin and TSH concentrations were normal before and during interferon-based
therapy, while thyroid-releasing hormone (TRH)-stimulated concentrations increased
significantly during therapy.
•
The adrenocorticotropic hormone (ACTH)/cortisol axis, basal and stimulated gonadotropin,
and testosterone concentrations were normal throughout the study.
•
Neither HCV RNA level nor transaminase (ALT and AST) levels were correlated with
hormone concentrations before or during therapy.
Conclusion
"GH
insufficiency is common in patients with chronic HCV infection," the authors
concluded. "While GH secretion improves during antiviral therapy, IGF-1 remains
low, indicating persistent GH resistance of hepatocytes."
"Whether
improvement in GH secretion during treatment is due to a direct drug effect or
related to the suppression of viral load could not be differentiated, as most
patients demonstrated a positive virologic response," they added.
01/08/08
Reference U
Plockinder, D Kruger, A Bergk, and others. Hepatitis-C Patients Have Reduced Growth
Hormone (GH) Secretion Which Improves During Long-Term Therapy With Pegylated
Interferon-alpha. American Journal of Gastroenterology 102(12): 2724-2731.
December 2007.
