Sickle-Cell Anemia (SCA)
Sickle-Cell Anemia (SCA)
Sickle-cell disease (SCD), or sickle-cell anaemia (SCA) or drepanocytosis, is a life-long blood disorder characterized by red blood cells that assume an abnormal sickle shape.While sickle-cell anaemia is not directly a chronic liver disease, the effects of multiple blood transfusion make it interesting in the context of hepatology. Sickle-cell disease patients often have some liver abnormality; these included abnormal liver function tests, jaundice, hepatic infarcts, acute and chronic viral hepatitis, choledocholithiasis, and cirrhosis, liver ultrasonographic changes or cholelithiasis.Sickle-cell disease is a qualitative problem of synthesis of an incorrectly functioning globin, whereas Thalassemia is a quantitative problem of too few globins synthesized.
Sickle-cell disease occurs more commonly in people from parts where malaria is common - tropical and sub-tropical regions. About 30% of all indigenous inhabitants of Sub-Saharan Africa carry the gene. Prevalence of sickle-cell disease in the US is approximately 1 in 5,000.
Sickle-Cell Disease and multiple blood transfusion
Blood transfusions help benefit sickle cell disease patients by reducing recurrent pain crises, risk of stroke and other complications. Many sickle cell disease patients are transfusion dependent and take part in a long term transfusion program.
Sickle-Cell Anemia and Transfusional Iron Overload
Because red blood cells contain iron, and there is no natural way for the body to eliminate it, patients who receive repeated blood transfusions can accumulate iron in the body until it reaches toxic levels. It is important to remove excess iron from the body, because it can gather in the liver (elevating hepatic iron concentration), and later in the heart and other organs and may lead to organ damage. Treatments are available to eliminate iron overload but despite being on chelation therapy, many patients on chronic transfusion have high levels of liver iron. Measurement of Liver iron concentration LIC is highly recommended in these patients.
Sickle-Cell Anemia and elevated Liver Iron Concentration (LIC)
Liver iron concentration (LIC) over 15.0 mg Fe/g dry weight is associated with increased risk of cardiac diseases. Gold standard for measuring hepatic iron concentration is analysis of liver needle biopsy specimens, however this has some major drawbacks. For blood tests like transferring saturation and serum ferritin there seems to be a poor correlation between serum ferritin levels and liver iron content (LIC).An innovative measurement of liver iron concentration (LIC) is done with a non-invasive imaging procedure, the quantitative MRI liver iron test.
Risk of elevated Liver Iron Concentration (LIC) for Sickle-Cell Patients
In sickle cell patients who are transfused, evidence suggests that they are at risk of liver fbrosis and cirrhosis as a result of iron overload. Howeverthe risk of heart iron loading in sickle cell patients appears to be very low compared to thalassaemia patients. Therefore in sickle cell patients, the risk of liver damage is likely to be much greater than the risk of heart damage due to iron overload.
Liver Iron Concentration (LIC) as early warning System for Sickle-Cell Patients
The liver can be considered the early warning system against later endocrine complications, due to iron overload. For sickle cell patients who are transfused, efective management of liver iron concentration is critical to ensure risk of morbidity due to iron overload is minimized.
Phlebotomy and Chelation as Therapy for Sickle-Cell Disease
Chelation therapy should begin when the liver iron is elevated. Some programs recommend liver biopsies at the initiation of chelation, and every two years thereafter, however there seems to be an alternative since the MRI measurement of liver iron concentration with Magnetic Resonance Imaging is far advanced. UK Sckle Cell Society is recommendeing this for measuring liver iron concentrations in patients with sickle cell disease.
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Studies and Publications regarding Sickle-Cell Anemia
- A. Olthof, P. Sijens, H. Kreeftenberg, P. Kappert, R. Irwan, E. van der Jagt, M. Oudkerk Correlation between serum ferritin levels and liver iron concentration determined by MR imaging: impact of hematologic disease and inflammationMagnetic Resonance Imaging, Volume 25, Issue 2, Pages 228-231
- Ataga KI, Stocker J (February 2009). "Senicapoc (ICA-17043): a potential therapy for the prevention and treatment of hemolysis-associated complications in sickle cell anemia". Expert Opin Investig Drugs 18 (2): 231–9.
- Fabiola Traina, Stefano Gonçalves Jorge, Ademar Yamanaka, Luciana R. de Meirelles, Fernando Ferreira Costa, Sara T.O. SaadChronic Liver Abnormalities in Sickle Cell Disease: A Clinicopathological Study in 70 Living Patients Acta Haematol 2007;118:129-135 (DOI: 10.1159/000107744)
- Karam, Lina B.; Disco, Deborah; Jackson, Sherron M.; Lewin, David; Mckie, Virgil; Baker, Robert D.; Baker, Susan S.; Laver, Joseph H.; Nietert, Paul J.; Abboud, Miguel R. (2008). "Liver biopsy results in patients with sickle cell disease on chronic transfusions: Poor correlation with ferritin levels." Pediatric Blood & Cancer 50(1): 62-65.
- Iron chelation therapy in sickle-cell disease and other transfusion-dependent anemiasHematology/Oncology Clinics of North America, Volume 18, Issue 6, Pages 1355-1377J.Kwiatkowski, A.Cohen