**6. β-Thalassemia workup**

#### **6.1. Laboratory studies**

erythroid hyperplasia, which may range between 25 and 30 times normal. Anemia may

118 Epidemiology of Communicable and Non-Communicable Diseases - Attributes of Lifestyle and Nature on Humankind

Increased erythropoietin synthesis may stimulate the formation of extramedullary erythropoietic tissue, primarily in the thorax and paraspinal region. Marrow expansion also results

High levels of iron, closely associated with denatured hemoglobin, have been found in the

Severe IE, chronic anemia, and hypoxia also cause increased gastrointestinal (GI) tract iron absorption. This is combined with increased iron from the breakdown of RBCs and the increased iron introduced into the circulation by the transfusions necessary to treat thalassemia, plus inadequate excretory pathways lead to progressive deposition of iron in tissues and

Free iron species, such as labile plasma iron as well as labile iron pool in the RBCs accumulate when transferrin saturation exceeds 70%. These free iron species generate reactive oxygen

The history in patients with thalassemia widely varies, depending on the severity of the condition and the age at the time of diagnosis. In most patients with thalassemia traits, no unusual signs or symptoms are encountered, children with thalassemia major usually present between 3 months and 1 year of life, and occasionally presentation is delayed to 4−5 years [15]. Some patients, especially those with somewhat more severe forms of the disease, manifest some pallor and slight icteric discoloration of the sclerae with splenomegaly, leading to slight enlargement of the abdomen. Thalassemia should be considered in any child with hypochro-

Patients with thalassemia minor are often asymptomatic. They have mild anemia and their Hb level is usually not less than 9−10 g/dl therefore pallor and splenomegaly are rarely observed.

species with eventual tissue damage, organ dysfunction, and death (**Figure 1**) [13].

mic microcytic anemia that does not respond to iron supplementation [15].

The stigmata of severe untreated α-thalassemia major included the following:

produce cardiac enlargement and sometimes severe cardiac failure [12].

in characteristic deformities of the skull and face, as well as osteopenia [13].

membrane of β-thalassemic red cells [14].

**5. Clinical presentation of β-thalassemia**

**•** Severe anemia, with an Hb level of 3−7 g/dl

**•** Massive hepatosplenomegaly

**•** Severe growth retardation

**•** Bony deformities

hemosiderosis occurs [13].

**5.1. History**

**5.2. Physical**

#### *6.1.1. Complete blood count and peripheral blood film examination*

In the severe forms of thalassemia, the Hb level ranges from 2 to 8 g/dl. MCV and MCH are significantly low. Reticulocyte count is elevated to 5–8% and leukocytosis is usually present. Platelet count is usually normal, unless the spleen is markedly enlarged. Peripheral blood film examination reveals nucleated RBCs and occasional immature leukocytes.

#### *6.1.2. Hemoglobin electrophoresis*

High performance liquid chromatography (HPLC) is now usually used as first-line method to diagnose hemoglobin disorders. HPLC or hemoglobin electrophoresis reveals absence or almost complete absence of Hb A, with almost all the circulating hemoglobin being Hb F. The Hb A2 percentage is normal, low, or slightly raised.

#### *6.1.3. Biochemical studies*


#### **6.2. Imaging studies**

Findings show skeletal changes, including thinning of the cortex, widening of the medulla, and coarsening of trabeculations, due to bone marrow hyperplasia in the long bones, metacarpals, and metatarsals. Skull bones show "hair-on-end." The maxilla may overgrow, which results in maxillary overbite, prominence of the upper incisors, and separation of the orbit. These changes contribute to the classic chipmunk facies observed in patients with thalassemia major [21]. Chest radiography is used to evaluate cardiac size and shape. Left ventricular function can be quantified using MRI, MUGA (multiple gated acquisition scan) or echocardiography [22].

Cardiac T2\*, a noninvasive procedure involves measuring the cardiac T2 with cardiac magnetic resonance (CMR). This procedure has shown decreased values in cardiac T2 due to iron deposit in the heart. Unlike liver MRI, CMR does not correlate well with the ferritin level, the liver iron level, or echocardiography findings. The liver is clear of iron loading much earlier than the heart, and so the decision to stop or reduce chelation treatment based on liver iron levels is misleading [23].

A poor correlation was noted between cardiac and hepatic iron concentrations as assessed by T2-MRI where approximately 14% of patients with cardiac iron overload were identified who had no matched degree of hepatic hemosiderosis [24].

#### **6.3. Molecular genetic analysis**

PCR-based procedures can detect the commonly occurring mutations in β-globin gene. The most commonly used methods are reverse dot blot analysis or primer-specific amplification, with a set of probes complementary to the most common mutations in each population. β-Globin gene sequence analysis is used to detect mutations in the β-globin gene in case of failure of targeted mutation analysis [25].

#### **6.4. Prenatal diagnosis**

Prenatal diagnosis is possible through analysis of DNA obtained through chorionic villi sampling at 8–10 weeks' fetal gestation or by amniocentesis at 14–20 weeks' gestation. In most laboratories, the DNA is amplified using the PCR assay test and then is analyzed for the presence of the thalassemia mutation using a panel of oligonucleotide probes corresponding to known thalassemia mutations. Prenatal diagnosis may be performed noninvasively, with the use of maternal blood samples to isolate either fetal cells or fetal DNA for analysis [26].
