Individuals with more severe IE have more significant anemia, and as a result may have growth retardation, chronic fatigue and malaise, bone pain, and worsening splenomegaly and still develop iron over load. Splenectomy is often performed when there is a component of hypersplenism contributing to worsening anemia. Gallbladder disease from increased red cell turnover and the development of pigment gallstones is quite common. Progressive EMH may result in paraspinal nodules as described previously. Thromboembolic events represent a major complication of thalassemia intermedia, occurring in 10% to 34% of patients. These events include stroke, pulmonary embolism, portal vein thrombosis, and deep vein thrombosis of the legs. Splenectomy is a risk factor for thromboembolic events in patients with thalassemia intermedia, resulting in thrombocytosis and allowing the prolonged circulation of damaged RBCs that generate increased amounts of thrombin. Clinical manifestations including the development of chronic, non-healing leg ulcers from poor perfusion and the effects of arterial endothelial damage. A possible hypercoagulable state may contribute to other manifestations of vascular disease such as cerebral infarcts and development of pulmonary hypertension, complications which commonly occur in patients with thalassemia intermedia with the latter being the primary cause of congestive heart failure. Some investigators consider the risk of thromboembolic events after splenectomy for thalassemia intermedia to be sufficiently high to warrant short-term anticoagulation in the perioperative period and during pregnancy. Oral contraceptives should be used with extreme caution, if at all. Interestingly, known genetic thrombophilias in other populations like factor V Leiden, the prothrombin gene mutation 20210, and MTHFR C677T mutations have not been associated with thrombotic risk in this population.
Extension of hematopoietic tissue beyond the confines of the bones occurs in patients with thalassemia intermedia as a result of the intense erythropoiesis. This complication occurs less frequently in patients with thalassemia major because of the partial suppression of erythropoiesis by regular transfusions. Masses of extramedullary hematopoietic tissue develop in the spinal epidural space, thorax, cranium, pelvis, and elsewhere. These masses may be detected as incidental findings on imaging studies of the chest or abdomen. In other instances, the masses produce symptoms by compressing neighboring structures. For example, patients with extramedullary hematopoietic masses may develop paraplegia from spinal cord compression or loss of visual acuity or visual fields caused by optic nerve compression. Additional clinical presentations of hematopoietic masses include pleural effusions and upper airway obstruction. Initiation of regular transfusions for patients with thalassemia intermedia or intensification of the ongoing transfusion program for patients with thalassemia major reduces the size of extramedullary hematopoietic masses and helps to prevent recurrences (see Tables 1 and 2). Additional bone changes are described subsequently.
Table1. Nontransfusion-Dependent Thalassemia Screening Recommendations
Table2. Transfusion-Dependent Thalassemia Screening Recommendations
Even in the absence of regular transfusions, many patients develop progressive iron overload because of increased absorption of dietary iron induced by IE and, in many cases, the intermittent administration of RBC transfusions. By the third or fourth decade of life, and occasionally even the second, the total iron burden may attain the levels seen in transfusion-dependent patients. Ferritin levels underestimate the degree of tissue iron loading in thalassemia intermedia, and assessment of LIC is more helpful in determining the need for chelation therapy. Iron overload may result in diabetes and endocrine disturbances, typically by the fourth decade of life, though cardiac deposition is relatively rare in true thalassemia intermedia individuals.
