Effect of ethosuximide on cortisol metabolism in the treatment of congenital adrenal hyperplasia.

BACKGROUND: Antiepileptics may affect cortisol metabolism through CYP3A4. There is little known about ethosuximide. CLINICAL CASE: Our patient is a 12-year-old girl with salt-wasting congenital adrenal hyperplasia (CAH) owing to 21 hydroxylase deficiency. A standard treatment regimen was initiated with satisfactory results until the age of 6 years, when she developed absence seizures treated with ethosuximide. She received such therapy until the age of 12 years, at which point ethosuximide was discontinued. During ethosuximide administration, she experienced worsening control of CAH disease activity that responded to progressive increases in hydrocortisone dose up to 28 mg/m2 per day. Despite high doses of hydrocortisone, she suffered no cushingoid symptoms. Her requirements for high glucocorticoid replacement doses resolved shortly after ethosuximide was discontinued. We provide data over 6 years demonstrating a correlation between adrenal hormone secretion, cortisol requirements and ethosuximide dose. CONCLUSION: This is the first case demonstrating an interaction between ethosuximide and hydrocortisone clearance in the treatment of salt-wasting CAH.

Hepcidin as a therapeutic tool to limit iron overload and improve anemia in ß-thalassemic mice.

Excessive iron absorption is one of the main features of ß-thalassemia and can lead to severe morbidity and mortality. Serial analyses of ß-thalassemic mice indicate that while hemoglobin levels decrease over time, the concentration of iron in the liver, spleen, and kidneys markedly increases. Iron overload is associated with low levels of hepcidin, a peptide that regulates iron metabolism by triggering degradation of ferroportin, an iron-transport protein localized on absorptive enterocytes as well as hepatocytes and macrophages. Patients with ß-thalassemia also have low hepcidin levels. These observations led us to hypothesize that more iron is absorbed in ß-thalassemia than is required for erythropoiesis and that increasing the concentration of hepcidin in the body of such patients might be therapeutic, limiting iron overload. Here we demonstrate that a moderate increase in expression of hepcidin in ß-thalassemic mice limits iron overload, decreases formation of insoluble membrane-bound globins and reactive oxygen species, and improves anemia. Mice with increased hepcidin expression also demonstrated an increase in the lifespan of their red cells, reversal of ineffective erythropoiesis and splenomegaly, and an increase in total hemoglobin levels. These data led us to suggest that therapeutics that could increase hepcidin levels or act as hepcidin agonists might help treat the abnormal iron absorption in individuals with ß-thalassemia and related disorders.

Hepcidin and Hfe in iron overload in beta-thalassemia.

Hepcidin (HAMP) negatively regulates iron absorption, degrading the iron exporter ferroportin at the level of enterocytes and macrophages. We showed that mice with beta-thalassemia intermedia (th3/+) have increased anemia and iron overload. However, their hepcidin expression is relatively low compared to their iron burden. We also showed that the iron metabolism gene Hfe is down-regulated in concert with hepcidin in th3/+ mice. These observations suggest that low hepcidin levels are responsible for abnormal iron absorption in thalassemic mice and that down-regulation of Hfe might be involved in the pathway that controls hepcidin synthesis in beta-thalassemia. Therefore, these studies suggest that increasing hepcidin and/or Hfe expression could be a strategy to reduces iron overload in these animals. The goal of this paper is to review recent findings that correlate hepcidin, Hfe, and iron metabolism in beta-thalassemia and to discuss potential novel therapeutic approaches based on these recent discoveries.