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Sickle Cell Disease
Published in Vincenzo Berghella, Maternal-Fetal Evidence Based Guidelines, 2022
Hemoglobin provides the oxygen-carrying capacity of erythrocytes, and exists as a tetramer of two α and two β protein subunits (α2β2), also known as hemoglobin A (HbA). Hemoglobin has normal variants which differ by their protein subunits and are present in most adult red blood cells. In most adults without hemoglobinopathy, 96–97% of circulating hemoglobin is HbA (α2β2), with 2–3% of hemoglobin A2 (α2δ2), and 0–1% hemoglobin F (α2γ2).
Haematology and oncology
Published in Jagdish M. Gupta, John Beveridge, MCQs in Paediatrics, 2020
Jagdish M. Gupta, John Beveridge
In thalassaemia major there is impaired synthesis of beta chains of haemoglobin which are required for the synthesis of haemoglobin A. As a result haemoglobin F is formed. As haemoglobin F is normally present in the newborn period, haemoglobin electrophoresis will not establish the diagnosis. Blood of the parents (heterozygotes) contains elevated levels of haemoglobin A2 (3.5-7%) and haemoglobin F (2-6%). Some heterozygotes may have normal levels of HbA2 with raised levels of HbF (5-15%) only.
Iron Deficiency Anemia
Published in Harold R. Schumacher, William A. Rock, Sanford A. Stass, Handbook of Hematologic Pathology, 2019
Donald P. Skoog, James R. Newland
Heterozygous alpha and beta thalassemia are common microcytic anemias. The combination of low normal to slightly decreased hemoglobin, high normal to slightly increased red cell count, moderately decreased MCV, and target cells is characteristic of thalassemia minor. In iron deficiency when the hemoglobin is comparable to that typical of thalassemia minor, the MCV is usually less abnormal. Serum ferritin and hemoglobin A2 levels usually suffice to make the distinction.
A MALDI-TOF mass spectrometry-based haemoglobin chain quantification method for rapid screen of thalassaemia
Published in Annals of Medicine, 2022
Jian Zhang, Zhizhong Liu, Ribing Chen, Qingwei Ma, Qian Lyu, Shuhui Fu, Yufei He, Zijie Xiao, Zhi Luo, Jianming Luo, Xingyu Wang, Xiangyi Liu, Peng An, Wei Sun
In clinical practice, examination of red cell indices and measurement of haemoglobin concentration is used to screen suspected cases of thalassaemia. However, due to the insufficient sensitivity and specificity of these methods, further examinations are still needed. Haemoglobin electrophoresis or high-performance liquid chromatography (HPLC) has been used for the quantification of haemoglobin A2 (Hb A2, or α2δ2) and foetal haemoglobin (Hb F, or α2γ2). However, the throughput of electrophoresis is limited and HPLC quantification of Hb A2 could be interfered with by the existence of Hb Lepore or Hb E variant due to their co-elution with Hb A2, which may result in a false increase of Hb A2 level [10]. The specificity and sensitivity of these methods for the diagnosis of thalassaemia are not satisfactory. For example, Noppacharn et al. [11] reported that HPLC yielded 76.4% sensitivity and 89.5% specificity for identification α-thalassaemia syndrome in the newborns of Thailand. Genetic analysis (e.g. gap-PCR, DNA sequencing) and family studies are necessary for the final confirmation of thalassaemia [12]. Although next-generation sequencing is more precise than traditional genotyping methods [13], its application is limited by the high cost and additional requirements for bioinformatics analysis.
Prevalence and molecular characterization of common thalassemia among people of reproductive age in the border area of Guangxi-Yunnan-Guizhou province in Southwestern China
Published in Hematology, 2022
GuiDan Xu, ChunFang Wang, JunLi Wang, Min Lin, ZhengYi Chang, JuHua Liang, XiaoHao Chen, ShiMao Zhong, XueJuan Nong, WuJun Wei, YiBin Deng
EDTA-K2-anticoagulated peripheral blood samples were collected from each participant. Next, blood cell parameters were determined by full automatic blood cell analysis (XN-1000, Sysmex, Japan), followed by analysis of hemoglobin components and levels by high-performance liquid chromatography (Variant II, BIO-RAD, USA). In conjunction with the local thalassemia prevention and control program, thalassemia screening was positive if it met any one of the following criteria: (1) Corpuscular volume (MCV) <82.5fL; (2) Mean corpuscular Hb (MCH) levels <27pg; (3) Hemoglobin A2 (HbA2) >3.5%; (4) HbA2 < 2.5%; (5) Fetal hemoglobin (HbF) >2.0%; and (6) Abnormal hemoglobin peaks. All individuals who were positive for thalassemia during screening were subjected to genetic testing.
Gastrointestinal vaso-occlusive crisis in sickle cell disease
Published in Baylor University Medical Center Proceedings, 2022
Garima Gautam, Robert Harmon, Raymond Foley
A 34-year-old woman with glucose-6-phosphatase deficiency and SCD presented with abdominal pain, nausea, vomiting, and dyspnea. She had a history of prior sickle cell crises and received transfusions; however, this episode had proven to be refractory to her home pain regimen. The temperature was 97.2°F; blood pressure, 70/44 mm Hg; heart rate, 104 beats/min; and oxygen saturation, 91% on a 3 L nasal cannula. Physical examination showed a diaphoretic patient in distress, with tachycardia, a systolic murmur, tachypnea, no respiratory wheezes or crackles, and a benign abdominal exam. Her potassium was 6.8 mmol/L; serum bicarbonate, 14 mmol/L; blood urea nitrogen, 13 mg/dL; creatinine, 1.6 mg/dL; lactic acid, 14.5 mmol/L; and troponin, 0.06 mg/dL. Her white blood cell count was 12,000 μ/L; hemoglobin, 6.4 g/dL; hematocrit, 19.6%; mean corpuscular volume, 101.4 fL; platelets, 200,000/μ; and reticulocyte count, 29.2%. Hemoglobin electrophoresis revealed a hemoglobin A of 29.8%, hemoglobin S of 60.3%, hemoglobin F of 7.2%, and hemoglobin A2 of 2.7%. Arterial blood gas disclosed a pH of 7.013, partial pressure of oxygen of 253.6 mm Hg, and partial pressure of carbon dioxide of 56.8 mm Hg. The total bilirubin was 2.3 mg/dL; direct bilirubin, 0.6 mg/dL; alkaline phosphatase, 59 U/L; aspartate transaminase, 60 U/L; and alanine transaminase, 43 U/L. Her blood cultures were negative, and a methicillin-resistant Staphylococcus aureus polymerase chain reaction test was positive. The patient was admitted to the medical intensive care unit for further management.