Hypoparathyroidism in beta-thalassemia major. Clinical and laboratory observations in 24 patients

In the last 18 years, we have observed 24 cases of hypoparathyroidism (HPT) in beta-thalassemia major. At present, 4.5% of patients followed regularly in our department have this complication. HPT is thought to be mainly the consequence of iron deposition in the parathyroid glands. The age of our patients when HPT was diagnosed ranged from 11 to 24 years (mean 16.5 years). Their serum ferritin levels ranged from 810 to 15,200 ng/ml (mean 3,772 ng/ml). The severity of HPT varied widely. In only 3 patients was hypocalcemia severe with signs of tetany, seizures or cardiac failure. The onset of HPT was preceded or followed in most patients by other endocrine and/or cardiac complications. We found no clear relationship between HPT and serum ferritin levels in our patients, suggesting either an individual sensitivity to iron toxicity or early damage of the parathyroid gland before chelation had reduced the iron overload. However, the diagnosis of no new cases of HPT in the last 3 years coinciding with the much improved regime of chelation therapy suggests that chelation may have helped to prevent the development of HPT.