Women on GH therapy have lower IGF-I levels, experience more adverse effects than men
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Women with growth hormone deficiency treated with GH therapy have lower insulin-like growth factor I levels at both baseline and follow-up and experience more adverse events than men, according to study data.
“By conducting this study, we have provided insights concerning the underlying mechanisms explaining the previously found inequality in long-term effects of GH replacement therapy in GH-deficient men and women,” Tessa N.A. Slagboom, MD, a PhD candidate in the department of endocrinology and metabolism at Amsterdam UMC in the Netherlands, and colleagues wrote in a study published in The Journal of Clinical Endocrinology & Metabolism. “Regarding previously stated hypotheses on undertreatment of GH-deficient women on both hyposomatotropism and hypogonadism, we found indications for the presence of undertreatment of the GH deficiency, but not of the secondary gonadal deficiency. We suggest physicians to be extra alert on adverse effects of GH replacement therapy in GH-deficient women since they might be due to direct effects of GH and therefore not be reflected in measured IGF-I levels.”
Researchers conducted a retrospective cohort study of adults with GH deficiency in the Netherlands. Data from 2,586 adults receiving GH therapy were obtained from the Dutch National Registry of Growth Hormone Treatment in Adults from 1998 to 2009. Baseline characteristics of each participant’s GH deficiency, the start of GH therapy, follow-up time after GH therapy began, IGF-I at baseline and follow-up, adverse events and long-term safety outcomes during GH therapy were collected. As part of the long-term safety analysis, researchers analyzed the risks for type 2 diabetes, benign and malignant neoplasms and recurrence of tumor growth for men and women.
The analysis included 1,335 men (median follow-up, 5.3 years) and 1,251 women (median follow-up, 5.63 years). Women received a higher median dose of recombinant human GH than men (0.38 mg vs. 0.3 mg; P < .001), though there was no difference after excluding women who were also taking oral estrogen.
Mean IGF-I levels increased from 13.82 nmol/L at baseline to 23.77 nmol/L at follow-up for men and from 11.3 nmol/L at baseline to 20.62 nmol/L at follow-up for women. The change in IGF-I from baseline to follow-up was similar for men and women. In subgroup analysis of eugonadal adults, men had a higher IGF-I level at follow-up than women (26.37 nmol/L vs. 21.55 nmol/L; P < .001).
Women experienced 10% more adverse events with GH therapy compared with men, with women twice as likely to report fluid retention in extremities, anemia and intestinal problems. Adverse events among 18% of women and 13% of men led to a reduction or temporary stop in GH therapy during follow-up (P = .001). A higher percentage of women reported multiple adverse events compared with men (8% vs. 6%; P = .02).
During follow-up, 4% of men and 3% of women developed type 2 diabetes, with similar risk between the two groups. More men developed neoplasms during follow-up compared with women (10% vs. 8%; P = .032). The risk for developing benign neoplasms was similar between men and women, but men had a higher risk for malignant neoplasms than women (HR = 0.56; 95% CI, 0.36-0.88; P = .012). A similar percentage of men (10%) and women (9%) diagnosed with a pituitary adenoma or craniopharyngioma at baseline had tumor recurrence during follow-up. During follow-up, 5% of men and 4% of women died, with no significant difference between the two groups.
“These results need to be confirmed in future research directly relating adverse events to GH dose and IGF standard deviation score, ultimately leading to improving GH replacement therapy regimens and hopefully also improve mortality for GH-deficient women,” the researchers wrote. “Until then, we do advise treating physicians to be specifically aware of the dilemma concerning undertreatment, and thereby the less beneficial effects of GH replacement therapy, at the expense of less side effects in GH-deficient women.”
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