snippet of RDW values from a CBC test report

Low RDW in CBC Blood Test Explained

Many blood count tests today write the RDW as a part of the CBC test results, as below picture:

screenshot of low RDW value from a CBC test report

This screenshot of a RDW value in a CBC report shows:

  1. RDW: is a shortcode of the medical term “Red-blood-cell Distribution Width”, RDW represents the degree of variation of the sizes of red blood cells inside human blood, the normal range of RDW is 11.5% up to 14.5%,

The thalassemia trait doesn’t elevate RDW and still be normal, that why the normal RDW doesn’t exclude anemia.

High RDW appears when you have anemia due to iron deficiency, medically (a type of microcytic hypochromic anemia).

  1. The “L” letter beside the RDW value: means “low” as usually represented in the medical reports, Low RDW than the reference limits is medically insignificant because of inaccurate blood cell automatic counting or due to sampling errors or other hidden unattended errors in the procedures, thus why many clinicians don’t rely on RDW values.
  1. The reference range for RDW readings (11.5 – 14.5): doesn’t mean it is normal when your RDW lye inside this range, rather the RDW values within the reference range mean either normal size variation without anemia or means anemia with single size RBCs (i.e. thalassemia).

Does low RDW a valid indicator in diagnosis of anemia?

Should you worry when RDW level is low?

When your RDW value is below the limits, you shouldn’t worry because any tiny error in the testing procedures can result in such a falsely low result and can’t indicate a disease or a medical issue, and it’s beneficial to know that Low RDW value doesn’t necessarily mean that red blood cells are all in the small size, but the normal RDW is a more significant indicator of single size RBCs.

Did you understand yet what does high RDW means?

Ferritin 18 HB 112 Iron 302

Q:67yrs man Ferritin 18 HB 112 Iron 302, Could you explain?

A blood test done a few weeks ago shows anemia. Ferritin ct. 18, Hemoglobin ct. 11.2, Iron ct. 302. From all I’ve been able to attain, my Iron is way too high and Hemoglobin and ferritin too low. In most cases, the Iron level seems to parallel the others, but mine doesn’t. Could you explain? Thanks.

Is My Hemoglobin Level Normal or Not?

Q: recently had a blood test and my hemoglobin level was 12.2,its lower than normal and they said that i cant donate blood,what could be wrong,i feel normal,i don’t feel any problems with my body,do i need to take measures to increase it? i am a 19 year old Male

A: Hemoglobin Normal Ranges Chart

Anemia chart

There are A LOT of causes of anemia; some serious and some benign and easily treated. What this all adds up to is that there is no way for anyone to provide any advice regarding anemia without a thorough history and physical exam. 

Read: what is hgb on a blood test?

Just to give you an idea of just how many causes and treatments there are for anemia see the excerpt below. This is heavily edited/excerpted from UpToDate and is in no way a complete treatment of the subject. Suffice it to say, there is not one person here who can tell you why you are anemic or how to treat it. There are far too many causes and if you don’t know the cause, you can’t effectively treat it. 

Side note: No, you do not “…by definition have pernicious anemia.” That is a specific diagnosis that requires an evaluation of your B12 levels. You did not mention a B12 level so it is impossible to say whether you have pernicious anemia or not. 

“Anemia can be caused by one or more of three independent mechanisms: decreased red blood cell (RBC) production, increased RBC destruction, and blood loss. 

Anemia types


Anemia will ultimately result if the rate of RBC production is less than that of RBC destruction. The more common causes for reduced RBC production include:

  1. Lack of nutrients, such as iron, B12, or folate. This can be due to dietary lack, malabsorption (eg, pernicious anemia, sprue, intestinal disease), or blood loss (iron deficiency). 
  2. Bone marrow disorders (eg, aplastic anemia, pure RBC aplasia, myelodysplasia, tumor infiltration) 
  3. Bone marrow suppression (eg, drugs, chemotherapy, irradiation). 
  4. Low levels of trophic hormones which stimulate RBC production, such as EPO (eg, chronic renal failure), thyroid hormone (eg, hypothyroidism), and androgens (eg, hypogonadism). Acquired inhibitors of EPO or the EPO receptor have also been described as causes of anemia.
  5. The anemia of chronic disease/inflammation, associated with infectious, inflammatory, or malignant disorders, is characterized by reduced availability of iron due to decreased absorption from the gastrointestinal tract and decreased release from macrophages, a relative reduction in erythropoietin levels, and a mild reduction in RBC lifespan. 


A RBC life span below 100 days is the operational definition of hemolysis. Hemolytic anemia will ensue when the bone marrow is unable to keep up with the need to replace more than about 5 percent of the RBC mass per day, corresponding to a RBC survival of about 20 days. Examples include: 

  1. Inherited hemolytic anemias (eg, hereditary spherocytosis, sickle cell disease, thalassemia major) 
  2. Acquired hemolytic anemias (eg, Coombs’-positive autoimmune hemolytic anemia, thrombotic thrombocytopenic purpura-hemolytic uremic syndrome, malaria)


Iron deficiency in the United States and Western Europe is almost always due to blood loss. Blood loss is the most common cause of anemia and may take any one of a number of forms: 

  1. Obvious bleeding (eg, trauma, melena, hematemesis, menometrorrhagia) 
  2. Occult bleeding (eg, slowly bleeding ulcer or carcinoma). 
  3. Induced bleeding (eg, repeated diagnostic testing, hemodialysis losses, excessive blood donation)

In addition to the loss of RBCs from the body, which the bone marrow must replace, loss of the iron contained in these cells will ultimately lead to iron deficiency, once tissue stores of iron have been depleted. This usually occurs in males and females after losses of ≥1200 mL and ≥600 mL, respectively. However, since about 25 percent of menstruant females have absent iron stores, any amount of bleeding will result in anemia in this subpopulation. 

Since availability of iron is normally rate-limiting for RBC production, iron deficiency associated with chronic bleeding leads to a reduced marrow response, worsening the degree of anemia.” 

What Does MCH Blood Test Mean in CBC test?

What Is MCH In Blood test?
MCH test can be defined as one of the comprehensive blood test (CBC), known as the complete blood count test.
MCH value is calculated from the hemoglobin reading and red blood cells count by a mathematical equation.
It is known as the average hemoglobin mass and used for diagnosing the causes of many diseases.
Red blood cells are one of the main blood components that take the shape of ball, as it contains hemoglobin, which is linked to the iron element and a number of different proteins.
MCH test:
The average mass of the hemoglobin molecule is analyzed by taking a sample of red blood cells
The hemoglobin mass in the red blood cells ranges between 26-33 pkg within the normal range.
In the case of high or low, there is a disturbance in the amount of iron in the blood, which is associated with many diseases, as in the case of red blood cell mass disorder, because of the association of reading hemoglobin.
Anemia is a condition where the result of MCH test is less than normal:
Due to the lack of iron needed to produce hemoglobin, and therefore the mass of hemoglobin molecule in blood is less than the rate sufficient to contain oxygen, showing the patient several symptoms is a preliminary indication of the magnitude of the test of the average hemoglobin red cells.
These symptoms include:
Physical and general impairment of motor activity.
Feeling dizziness and blurry vision, especially in cases of changing the position of the body from sitting directly.
Weakness of the ability of the body to exercise.
The appearance of paleness and signs of depression in the face.

MCH test can detect early Sickle cell anemia:
MCH test is one of the most important tests to detect the disease, which affects the red blood cells to take the shape of sickle, which is the origin of the label.
Where the disease is spread clearly in the Mediterranean region,
The disease is caused by the production of bone marrow for abnormal cells due to a number of factors and influences, the most important genetic factor.
Where the problem lies in a defect in one of the nucleic acids (RNA),
Therefore, MCH test should be performed when symptoms associated with the disease are present:
Feeling dizzy when doing a sudden muscle strain.
Acute bronchitis attacks.
Occurrence of visual disorders.
The occurrence of kidney failure leads in many cases to the formation of gravel.
Fracture and joint stiffness.
The occurrence of vascular disorders may lead to an increase in blood pressure or the occurrence of strokes of the heart or brain.