Diagnosis of Thalassemia on Dried Blood Spot Samples by High Performance Liquid Chromatography

A Formula to Identify Potential Cases of β-Thalassemia/HbE Disease Among Patients With Absent HbA, HbE >75% and HbF Between 5 and 15

OBJECTIVE

To establish a simple formula to be used for discrimination between β-thalassemia/hemoglobin E (β-thal/HbE) and homozygous hemoglobin (Hb)E in specimens with absent hemoglobin (Hb)A, HbE of greater than 75%, and HbF between 5% and 15%.

METHODS

We analyzed laboratory results from February 2015 through February 2018. Molecular analysis for diagnosis of β-thal mutation and HbE was performed in specimens that contained HbE of greater than 75% and HbF from 5% to 15%, as measured by high-performance liquid chromatography (HPLC). HbA2 and HbF levels were also measured by capillary electrophoresis. Then, the formula (6 × HbA2 + HbF)/MCV was developed.

RESULTS

The score of 0.9 or higher was found in all 19 β-thal/HbE specimens (100%) and only 8 of 65 homozygous HbE specimens (12.3%). Also, the formula yielded 90.5% efficiency in identifying β-thal/HbE disease, and the efficiency was found to be higher compared with when the HbA2 value of greater than 6% was used by itself (85.4%).

CONCLUSION

The formula (6 × HbA2 + HbF)/MCV, with a cutoff point at 0.9, could identify the potential cases of β-thal/HbE disease among patients with absent HbA, HbE of greater than 75%, and HbF between 5% and 15%.

Current prevalence of intestinal parasitic infections and their impact on hematological and nutritional status among Karen hill tribe children in Omkoi District, Chiang Mai Province, Thailand

Intestinal parasitic infection represents a substantial problem for children living in rural or limited resources areas and significantly relates to anemia and nutritional status. This study aimed to determine the current prevalence of intestinal parasitic infections among school-age children of Karen hill tribe population in Omkoi District, Chiang Mai Province, Thailand and assess the impact of intestinal parasitic infection on hematological and nutritional status in those children. A total of 375 Karen hill tribe children, 6-14 years of age, in Omkoi District were randomly selected to participate in this study. Stool samples were collected and examined for intestinal parasitic infection through formalin-ether concentration method. Blood samples were collected for hematological and iron analysis. The overall prevalence of intestinal parasitic infection was 47.7% (179/375), with single infections (29.3%) and polyparatism (18.4%). The most common pathogenic parasite was Trichuris trichiura (16.0%), followed by Ascaris lumbricoides (13%) and Giardia lamblia (3.5%). In addition, non-pathogenic amoeba, Entamoeba coli was observed with a high prevalence rate (31.2%). Anemia and eosinophilia prevalence were 6.40% (24/375) and 74.7% (280/375), respectively. Eosinophilia was significantly more prevalent in children with intestinal parasitic infection compared to uninfected children. Among 249 children, 13.7% were iron deficiency, 9.6% were thalassemia and hemoglobinophathy and 8% were G-6-PD deficiency. A high prevalence infection rate was significantly associated with eosinophilia, but independently related to anemia and iron deficiency. Intestinal parasitic infections are endemic in school-age children of Karen hill tribe population in Omkoi District. These data highlight the need for an integrated approach to control transmission of intestinal parasites and improve the health and sanitation status of Karen hill tribe children in Thailand.

Red Cell Indices and Formulas Used in Differentiation of β-Thalassemia Trait from Iron Deficiency in Thai Adults

β-Thalassemia (β-thal) and iron deficiency cause most microcytic anemias. Red cell indices and formulas have been established as simple, fast, and inexpensive in discrimination between these two hematological disorders in school children. However, whether these formulas could be applied to diagnose β-thal trait and iron deficiency in adult Thai subjects is unclear. The aim of this study was to examine the diagnostic accuracy of five red cell indices [red blood cell (RBC) counts, mean corpuscular volume (MCV), mean corpuscular hemoglobin (Hb) (MCH), mean corpuscular Hb concentration (MCHC), and red cell distribution width (RDW)] and nine formulas (RDW/RBC, RDW Index, Sirdah, Green and King, Mentzer, England and Fraser, Ehsani, Srivastava and Shine and Lal). Their sensitivity, specificity, positive predictive value (PPV), and negative predictive values (NPV), efficiency, and Youden's Index were analyzed in 102 β-thal trait and 64 iron deficiency adult Thai subjects. The RDW/RBC formula proved to be the most reliable index as they had 100.0% specificity and PPV and the highest efficiency (94.58%) and Youden's Index (91.18%), as well as high sensitivity (91.18%) and NPV (87.67%). Therefore, this formula could be used in initial discrimination of β-thal trait from iron deficiency in adult Thai subjects.

Red cell indices and formulas used in differentiation of β-thalassemia trait from iron deficiency in Thai school children

Red cell indices and formulas have been established as simple, fast, and inexpensive means for discrimination between the β-thalassemia (β-thal) trait and iron deficiency. However, there were no reports of the diagnostic reliability of different red cell indices and formulas in discrimination of β-thal trait from iron deficiency in the Thai population. The aim of this study was to examine the diagnostic accuracy of five red cell indices [red blood cell (RBC) count, mean corpuscular volume (MCV), mean corpuscular hemoglobin (Hb) (MCH), mean corpuscular Hb concentration (MCHC), and red cell distribution width (RDW)] and eight formulas (Sirdah, Green & King, RDW Index, Menzler, England & Fraser, Ehsani, Srivastava, and Shine & Lal). Their sensitivity, specificity, positive and negative prognostic value and efficiency, were analyzed in 77 Thai school children, 21 with the β-thal trait and 56 with iron deficiency. The Sirdah and Srivastava formulas proved to be the most reliable indexes as they had 100.0% sensitivity and negative predictive value, the highest efficiency (97.4%), and the highest Youden's Index value (96.4%). Therefore, these formulas could be used in initial discrimination of the β-thal trait from iron deficiency in Thai school children.

Anemia in patients with coinherited thalassemia and glucose-6-phosphate dehydrogenase deficiency

Thalassemia and glucose-6-phosphate dehydrogenase (G-6-PD) deficiency are genetic disorders that cause hemolytic anemia. In areas with high frequencies of both hematological disorders, coinheritance of G-6-PD deficiency with thalassemia can be found. Whether G-6-PD deficiency, coinherited with thalassemia, enhances severe anemia is still unclear. Hematological parameters between thalassemia carriers with G-6-PD deficiency and those without G-6-PD deficiency were compared. The G-6-PD deficiency was diagnosed in 410 blood samples from thalassemia patients using a fluorescent spot test. The levels of hemoglobin (Hb), packed cell volume (PCV), mean corpuscular volume (MCV) and Hb A2/Hb E [β26(B8)Glu→Lys; HBB: c.79G>A] were measured using an automated blood counter and high performance liquid chromatography (HPLC), respectively. The G-6-PD deficiency was found in 37 samples (9.02%). Mean levels of Hb, PCV, MCV and Hb A2/E were similar between the two groups. Thus, G-6-PD deficiency did not enhance red blood cell pathology or induce more anemic severity in thalassemia patients.

Incidence of β-thalassemia carrier on 1495 couples in preconceptional period

OBJECTIVE

This research, conducted on 1495 couples in preconceptional period, demonstrates how the study of globular resistance of erythrocytes (GRO) is not a first choice test and not useful as other more accurate tests to identify subjects with β-thalassemia trait. Instead, the complete blood count (CBC) and the evaluation of HbA, HbA2 and HbF by high pressure liquid chromatography (HPLC) are essential.

METHODS

Each couple arrived in our laboratory to screen for β thalassemia. In case of patients with positive (240) or doubtful (112) results, we studied β-globin gene.

RESULTS

Of the 2990 subjects examined, we found 280 subjects with β-thalassemia trait (9.36%). During biochemical tests, among 112 subjects with doubtful--normal GRO or altered GRO--results, 40 of them resulted positive for the molecular analysis, while 72 of them did not show mutations in β-globin genes. The 2710 samples with non-carriers of β-thalassemia trait presented as mean evaluation of HbA2 2.6%, while the 280 subjects with β-thalassemia trait presented as mean evaluation of HbA2 4.8%. Molecular study showed that the β thalassemia phenotype is caused by a small number of mutations, whose regional distribution is typical.

CONCLUSIONS

In the presence of thalassemic parameters in the CBC, the accurate and precise quantification of hemoglobin HbA2 is essential for the diagnosis of β-thalassemia trait. DNA mutation analysis provides the most effective way to detect primary gene mutations. The mutations identified in this work can be identified with a simple and inexpensive kit. This means, in economic terms, a significant savings for health spending.

Development of control material for hemoglobin analysis

There is no certified control material for hemoglobin analysis which has the hemoglobin (Hb)A

Washed and dialysed erythrocytes of normal individuals and patients with β-thalassemia trait, HbE trait, β-thalassemia/HbE disease, homozygous HbE were lysed in 5% sucrose solution. The lyophilized hemoglobin control materials were prepared by using a freeze-drying (lyophilization) method. The high performance liquid chromatography (HPLC) analysis of lyophilized hemoglobin was performed after storing at –20°C for 1, 15 and 30 days and for 3 months.

The chromatograms of lyophilized hemoglobin control materials showed similar patterns and similar levels of HbA, HbA

The lyophilized hemoglobin could be developed and used as control materials for hemoglobin analysis.