Adrenal dysfunction:
The red cell transfusions increase the
iron overload which, in turn, affects the endocrine function of the pituitary
causing decreased height and weight. The excess iron has the potential to
disrupt adrenal function which results in low cortisol levels (Srivasta
et al., 2005).
Adrenal functional abnormalities are
minor and clinically insignificant. This might have a teleological explanation,
where homeostasis is designed to preserve the life saving hormone cortisol,
even in the most adverse circumstances (Srivasta et al., 2005).
Gulati et al. (2000)
reported hypocortisolism in 13% of patients (the youngest of whom was 5 years
old).
Srivasta et al. (2005) assessed the adrenal endocrine function in
a group of transfusion dependent β thalassemic patients between 10 and 20 years
of age. Cortisol levels were assayed before and after ACTH stimulation with 1µg
and 250 µg. 45% had in vitro evidence of adrenal dysfunction. A statistical
significant correlation between wasting and the basal cortisol level was observed.
In comparison to the involvement of other endocrine axes in polytransfused
thalassemics, the adrenal endocrine function abnormalities are minor and
clinically of little consequence.
McIntosh et al. (1976) studied 6
patients with thalassemia major. Cortisol response to insulin-induced
hypoglycaemia was normal in all. There was also normal cortisol response to
ACTH. However, they documented raised ACTH values in all the cases and
suggested that this could be due to end organ unresponsiveness.
The implications of hypofunction of the
adrenals in a child with an already compromised homeostasis due to chronic
anemia can be serious, so thalassemics with low baseline cortisol should be
closely followed with periodic 1µg and 250 µg ACTH tests to detect progression
to full blown adrenal insufficiency (Srivasta et al., 2005).
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