Growth hormone is important for the development and function of the immune system, but there is controversy on whether
growth hormone deficiency is associated to
immune disorders. A model of
isolated growth hormone deficiency may clarify if the lack of
growth hormone is associated with increased susceptibility to
infections, or with an altered responsiveness of the immune system. We have studied the frequency of
infectious diseases and the immune function in adults with congenital, untreated
isolated growth hormone deficiency. In a cross-sectional study, 35 adults with
isolated growth hormone deficiency due to a homozygous mutation in the
growth hormone releasing hormone receptor gene and 31 controls were submitted to a clinical questionnaire, physical examination serology for tripanosomiasis,
leishmaniasis, HIV,
tetanus,
hepatitis B and C, and serum total
immunoglobulin G, M, E and A measurement. The immune response was evaluated in a subset of these subjects by skin tests and response to vaccination for
hepatitis B,
tetanus, and bacillus Calmette-Guérin. There was no difference between the groups in history of
infectious diseases and baseline serology.
Isolated growth hormone deficiency subjects had lower total
IgG, but within normal range. There was no difference in the response to any of the vaccinations or in the positivity to
protein Purified Derived,
streptokinase or
candidin. Adult untreated
isolated growth hormone deficiency does not cause an increased frequency of
infectious diseases, and does not alter serologic tests, but is associated with lower total
IgG levels, without detectable clinical impact.