ENDOCRINE COMPLICATIONS OF THALASSEMIA MAJOR
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ndocrine abnormalities are among the
common complications of thalassemia despite early establish-ment of appropriate
chelation therapy, problems such as delayed sexual maturation and impaired
fertility may persist. Determining the prevalence of endocrine compli-cations
is difficult because of difference in the age of the first exposure to
chelation therapy, and the continuing
improvement in survival in well-chelated patients (De Sanctis, 2004).
In a report of 342 North
American patients who had thalassemia major, 38% of subjects had at least one
endocrinopathy, most commonly hypogonadism, and 13% had more than one
endocrinopathy (Kwiatkowski, 2008).
Growth retardation:
Growth retardation is common
in thalassemia major. Patterns of growth are relatively normal until the age of
9-10 years when growth velocity begins to slow. The key contributing factors to
stunted growth in patients with thalassemia may include chronic anemia,
transfusional iron overload, hypersplenism, and chelation toxicity (De
Sanctis 1991).
Before the
introduction of hypertransfusion and chelation therapy in the routine
management of patients with β-thalassemia major, chronic tissue hypoxia and
iron toxicity from transfusion hemosiderosis have been implicated as major causes of growth retardation (Low, 2001).
Causes
of short stature in thalassemia: Causes of
Genetic, malnutrition, socioeconomic status, chronic
anemia, GH insufficiency, associated endocrine complications, zinc deficiency,
DFX "toxicity", chronic liver disease and poor compliance to DFX (De Sanctis
2008).
Progressive
accumulation of iron in the body in thalassemic patients results from repeated
blood transfusion and increased absorption of dietary iron because of increased
ineffective erythropoiesis. Without chelation, hemosiderosis can lead to tissue
damage due to free radical formation, lipid peroxidation resulting in
mitochondrial, lysosomal and sarcolemal damage and increased collagen
deposition secondary to increased activity of the iron-dependent protocollagen
proline hydroxylase enzyme activity (Low, 2001).
Modern medical therapy has allowed
thalassemic children to grow normally in the first decade of life but growth
retardation continues to be observed in a significant proportion of these
adolescents (Low, 2001).
Several mechanisms have been suggested to cause disorders
of GH secretion:
1. Neurosecretory
dysfunction
2. Hypothalamic
growth-hormone-releasing hormone deficiency
3. Pituitary GH
deficiency
4. Increased
somatostatin activity (De Sanctis, 2008).
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