The veteran "microscope" explores the true culprit of anemia

01

【Preface】

Anemia is when the hemoglobin concentration is below the lower limits
of the corresponding age, sex, and altitude groups.
According to the pathological mechanism, it can be divided into three categories
: decreased erythropoiesis, destruction and excessive loss.
To diagnose these diseases, blood routine and reticulocyte count should first be used to determine the diagnosis, degree and type of anemia; Then select special tests according to clinical data, such as folic acid/B12 measurement, bone marrow examination, body iron status indicators, hemolysis test, hemoglobin electrophoresis, flow cytometry and gene analysis, etc.
, to look for the primary disease
of anemia.

02

【Case History】

The child, male, 1 year old, was admitted to the hospital with the main complaint of "fever for 3 days", and the diagnosis was: acute purulent tonsillitis
.
3 days ago, fever, no chills, no cough, runny nose, self-administered oral medication, still repeated fever, now for further diagnosis and treatment came to our hospital for hospitalization on August 6
.
Physical examination shows pharyngeal redness, large double tonsils, and more white discharge
.

Usual blood results: WBC 5.
6×109/L, RBC 5.
37×109/L, Hb 100g/L, PLT 255×109/L, hypersensitivity CRP 21.
96mg/L
.
Clinically carry out corresponding anti-infection and rehydration treatment
.
Ask the family, the child's previous anemia history, additional diagnosis: mild anemia to be treated
.

On August 11, the blood routine results were Hb 104g/L, MCV 61.
0fl, MCH 19pg; Microscopy rules are triggered, and a moderate amount of target red blood cells is visible on microscopy, see Figure 1
.
In communication with the clinic, it is recommended to add reticulocyte count and ferritin examination, and the corresponding test results are normal, temporarily ruling out anemia caused by abnormal hematopoietic stem cells and insufficient hematopoietic raw materials, as well as hemolytic anemia caused by red blood cell destruction, see Figure 2
.

Fig.
1 Routine blood results and target red blood cells in blood smear

Fig.
2 Results of reticulocytes and ferritin in children

The results were fed back to the clinic again, and combined with the history of anemia in both parents of the child, thalassemia genetic testing
was recommended.
The examination results showed that the α-globin gene test was abnormal,-- the SEA deletion variant, the genotype was standard (mild), and the clinical diagnosis was mild α thalassemia
.
After treatment, the pharyngeal tonsils and body temperature returned to normal, and it was recommended to pay attention to the prevention of upper respiratory tract infection, regularly review blood routine, and dynamically observe anemia after
discharge.

03

【Case Study】

The results of blood routine in this case showed mild anemia, and the platelet-related parameters were not numeric, which triggered the microscopic examination rules formulated by our department, and the manual microscope microscopy was carried out according to the process
of pushing the film.
Microscopic examination showed a medium amount of red blood cells of different sizes, and the central light staining area was not significantly enlarged, and a medium number of target red blood cells
was seen.
Diseases
such as thalassaemia, iron deficiency and bone marrow hematopoietic dysfunction are not excluded.

After adding reticulocyte count and ferritin, the test results are normal, combined with the child's parents have a history of anemia, the possibility of thalassaemia is high, and it is recommended to test the gene for
thalassaemia.
The results of genetic testing showed that α-globin gene test was abnormal,-- SEA deletion variant, the genotype was (--SEA/αα), and the clinical diagnosis was mild α thalassemia
.

04

【Knowledge Expansion】

Anemia is not a diagnosis of a disease in itself, but rather a group of clinical manifestations
caused by diseases of different causes.
The diagnostic idea of anemia is to first determine the existence and extent of anemia, determine the type of anemia according to the blood smear and red blood cell index, and then determine further examinations based on medical history and physical examination data, such as reticulocyte count, bone marrow examination, evaluation of iron storage status, hemolysis test, etc.
to further look for the cause of anemia [1].

Thalassemia is a hemoglobinopathy with abnormal hapeptide chain number synthesis and is an autosomal recessive disorder, including the common β-thalassemia and the rare α-thalassemia
.
α-thalassemia is an autosomal recessive anemia caused by partial or complete inhibition of the synthesis of α globin peptide chains, resulting in insufficient hemoglobin synthesis
.

α-thalassaemia mutations can be divided into deletion and non-deletion types
.
According to the number of missing α genes, it can be divided into α+ thalassaemia (missing 1 α gene, -α/) and α0-thalassaemia (missing 2 α genes ,--/).

A nondeletional mutation (αTα or ααT) refers to a point mutation in the α1 or α2 gene or the deletion of several bases, usually defined as α+ thalassaemia
.
The severity of the α-assemination phenotype is directly related
to the copy number of the α gene that has lost function.

α thalassaemia is divided into four phenotypes: (1) quiescent α-thalassaemia, 1 α-gene loss of function; genotypes are (-α/αα, ααT/αα, or αTα/αα); (2) Light α-thalassaemia, loss of function of 2 α-genes; genotypes are (--/αα, -α/-α, -α/ααT or αTα/αTα); (3) HbH disease, loss of function of 3 α-genes; The genotype is (---/-α or --/αTα); (4) HbBart's edema fetal syndrome, 4 α-genes lose function; genotype is (--/--)[2].

05

【Case Summary】

This case describes a child who was initially screened for the cause of anemia through traditional microscopic examination, and further diagnosed with α-thalassaemia
through genetic testing.
Facts have proved that with the rapid development of various automated inspection equipment in the laboratory department, microscopes still have a place to
play.
As a traditional test item, morphological examination can still provide clinicians with valuable diagnostic information
.
While giving full play to the advantages of modern automated inspection technology, the inspector should not ignore the important value
of cell morphological examination with traditional manual microscopy as the main means.

【References】

[1] Xia Wei, Yue Baohong.
Clinical hematology test[J].
Huazhong University of Science and Technology Press,2013,

[2] Clinical Practice Guidelines for Genetic Diseases, Medical Genetics Branch of Chinese Medical Association.
α-Clinical practice guidelines for thalassemia[J].
Chinese Journal of Medical Genetics,2020, 37(3)