[pronut-hiv] Growth hormone production reduced in HIV-positive men with fat redistribution

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Growth hormone production reduced in HIV-positive men with fat
redistribution 

The amount of growth hormone produced by HIV-positive men with fat
redistribution is lower than in men without HIV and than in HIV-infected
women with a similar age and body composition, according to a study
published in the 4th April edition of AIDS. The study also found that
growth hormone production is lower in white patients than non-white
patients. 

Growth hormone is produced by the pituitary gland at the base of the
brain and is responsible for normal growth and development in the body.
Patients with fat redistribution as a side-effect of HIV treatment are
thought to be at risk of deficiencies in growth hormone production. This
has resulted in growth hormone being tested as a treatment for body fat
redistribution, along with other factors than can stimulate the body to
increase its growth hormone production, to reduce their risk of
cardiovascular disease. 

Gender is known to affect the levels of growth hormone production among
HIV-negative patients, but its effect in HIV-positive patients has not
been assessed. The impact of race on the production of growth hormone is
also poorly understood in patients with HIV. 

Accordingly, doctors from Massachusetts General Hospital in Boston
wished to examine the effects of gender, race and fat redistribution on
growth hormone production among HIV-positive patients. They hoped that
this would allow them to work out which patients are at risk of low
growth hormone production. This may help the identification of patients
who will benefit from growth hormone treatment and avoid the risk of the
hormone's side-effects by giving it to patients who do not need it. 

The team of doctors measured growth hormone levels in 139 men and 25
women in response to a standard testing protocol consisting of growth
hormone releasing hormone and arginine injections. All of the patients
had evidence of fat redistribution after at least twelve weeks of stable
antiretroviral therapy. 

The doctors found that the women in the study had higher levels of
growth hormone production than the men. This was reflected both in the
peak levels of growth hormone that were detected (mean 36.4 vs. 18.9
ng/ml; p < 0.001) and in the total production of growth hormone over a
two-hour measurement period (mean 2679 vs. 1284 mg.min/dl; p < 0.001). 

When they looked at the effects of race, the investigators found that
Caucasian men had lower total production of growth hormone than
non-Caucasian men (mean 1146 vs. 1831 mg.min/dl; p = 0.04), although the
peak growth hormone levels were not statistically different. 

However, race was not linked to growth hormone production in the
HIV-positive women. 

"HIV-infected men with fat redistribution have significantly reduced
growth hormone peak responses and increased failure rates to
standardised growth hormone testing in comparison to healthy male
control subjects and to HIV-infected women of similar age and body mass
index," the investigators conclude. "Growth hormone secretion is related
to gender and race in HIV-infected patients." 

The group of doctors also wished to work out a cut-off value to define
growth hormone deficiency in HIV-positive patients. By comparing the
peak growth hormone levels between their cohort of HIV-positive patients
and a control group of 51 HIV-negative people of similar age, body mass
relative to height and race, they found that a cut-off of 7.5ng/ml was
optimal for men. 

"The cut-off of 7.5 ng/ml provided the optimal separation between the
HIV and control groups, while maintaining good specificity, i.e. less
than 10% of the controls failed," write the investigators. "Using this
cut-off approximately one third with fat redistribution fail the growth
hormone releasing hormone plus arginine test, and this can be considered
at least relatively growth hormone deficient." 

However, they were unable to calculate a suitable cut-off value for the
women in the study, as the HIV-positive and -negative women had similar
rates of failure when they tested a range of cut-off values for peak
growth hormone levels. 

The investigators found that growth hormone production was unaffected by
use of different types of anti-HIV drugs in either sex or by menstrual
status in HIV-positive women. However, the degree of growth hormone
deficiency was linked to the ratio of waist to hip size, a marker of fat
gain around the central organs in HIV-positive men. 

This study's findings indicate that taking race, waist to hip ratio and
the response to the growth hormone releasing hormone plus arginine test
can help doctors identify which HIV-positive men may benefit from growth
hormone treatment. However, it failed to draw strong conclusions on
which women would benefit from growth hormone treatment. 

"Further studies with larger numbers of women will be necessary to
investigate growth hormone responses in HIV-infected women and the need
for growth hormone augmentation in this population," the investigators
write. 

Reference 

Koutkia P et al. Growth hormone secretion among HIV infected patients:
effects of gender, race and fat redistribution. AIDS 20: 855-862, 2006.