If both the RDW and MCV levels are increased, there are several possible causes. One possible cause is liver disease

Another cause of high RDW & MCV levels is hemolytic anemia AND megaloblastic anemia

high RDW level and a low MCV:IDA , thalessemia intermedia ,

high RDW level and a normal MCV: beginning stages of vitamin B12 or folic acid deficiency. beginning stages of iron deficiency anemia,

you can also read this link about interpreting RDW and show that low RDW is not important very much

Http://emedicine.medscape.com/article/2098635-overview

Two peaks in the RDW can also indicate two red cell populations, such as in a person that just received a transfusion.

I call RDW as "Lazy Person's Peripheral smear" - That's what, it gives information about. Normal RDW is between 10.2% to 14.5%. So what it describes essentially the normal variation in red cell size - as in Normal state, some red cell are new - reticulocytes [about 2% or so], then some old cells are fragmented, so the normal RDW is calculated to be between those values. A Wide RDW, rather than high RDW value, suggests that there is a greater variation in cell size and red cells of different sizes are present, and often suggests mixed anemia. Wide RDW with Normal MCV suggests, presences of some small cells and other large cells and may have both microcytic and macrocytic cells.

Low or narrow RDW is likely of no clinical significance, and may indicate has not much old fragmented cells or reticulocytes, as reticulocytes are larger than mature RBCs.

I don't think that a low RDW is of significance in the settings you described. On the other hand, a high RDW warrant examine the blood film even if Hb is normal.

Red cells, like most of nature, has a normal distribution.

Both red cell volume and hemoglobin concentration have a normal distribution. Automatic cytometer calculate them and present to us like two parameters: MCV (medium corpuscular volume) and MCH (medium corpuscular hemoglobin). Both are medium measure.

RDW (red distribution width) really show us the homogenicity of volume red cell population. Low RDW is not pathological, it is completely normal. High RDW means non normal red cell population: transfusion, bone marrow impaired (myelodisplasia), iron deficiency, response to correct treatment, etc

In case of hypocromic mycrocitic ananemia, RDW value can orientate us!

If RDW is normal (or low) probably it is a talasemia (beta or alpha)

If RDW is high, we must rule out an iron deficiency.

Hi.. i believe there is no significant indication for this criteria or value in apposite of the high value which give indication for anemic and thalasemia cases

A low RDW means that the erythrocytes are very uniform in size - but it says nothing about what that size is. However if the rest of the CBC is fine, then there is probably no cause for concern. A blood examination may help evaluate further.

There is no significance if RDW is lower than normal range. This means that there is lesser variation in red blood cell sizes than seen in majority of healthy individuals (who fall in the normal distribution).

Fresh blood samples or blood collected from voluntary donors population for transfusion purpose, contain different sub-population of red cell[ new and 120 days cells]. These can be quantitatively separated by density gradient centrifugation for characterization. Reticulocytes being largest so are aggregated cells. As red cells aged , in blood bank setting, MCV increase so do K, Hb, Microvesicles and Annexin V[ which is the cytosolic components of all cells]. The latter two are good markers of red cell storage lesion , apoptosis, necrosis , netosis and fragmentation . Good correlation exist between soluble and micro-vesicle bound Annexin v released.

From laboratory stand points these are essential markers of processing /storage induced red cell storage lesion[ filtration, suspension in various storage media and various viral inactivation technologies]. There are also loss of red cells membrane adhesion proteins during storage easily measured by ELASA and flowcytometry technology[ for further info read about details in several publication by Seghatchian in TRASCI ].

The clinical significant of these altered with a higher MCV and microvesiculated cells are not fully established as they be clear from circulation very quickly but it is believed they may have role in immunomodulation. Perhaps attempt should be made in the rate clearance of red cells with variable or higher RDW values in normal patient populations.

A challenging project for new comers in the growing field of medicine.

The RDW formula is 1SD/MCV. Consequently, RDW values change depending on these two parameters. An increasing of the SD (due to an RBC population with increased cell diameter dispersion) determines by itself an increase of RDW. In these conditions, a decreasing of the MCV further increases the value of RDW. This case occurs in both iron deficiency and thalassaemia.

Conversely, with the same value of SD, the RDW decreases (or not increases) if a macrocytosis is present. For these reasons, the RDW is unable to describe the anisocytosis in the B12/folates deficiency. All this because apart from the pathophysiological consideration in case of anaemia, it all boils down to a simple mathematical calculation: The result of a fractional calculation varies in direct or inverse function with the variations of the numerator or the denominator respectively. So a decreasing of RDW can occur in a normal subject having a homogeneous RBC population with MCV close to the upper limit of the reference

Low RDW can be a sign of pulmonary hypertention pre or post capillary.

Only pathologies with modifications of the hematic crasis may be associated with changes in the RDW. Consequently, the evaluation of the RDW is devoid of any diagnostic significance in these cases. In pathologies that are not associated with modifications of the blood crasis or do not affect, variations of the RDW do not have any physiopathological verisimilitude.

As a result, the RDW is an useless diagnostic parameter in any non-anemic situations. In the anemias is only sparsely useful because of its methodological limitations.

It was a lapsus RDW IS INCREASED in pulmonary hypertension

Antonio has very well defined the fallacies introduced due to SD being divided by MCV and expressed as %CV. Unfortunately RDW has not come from any medical technologist or haematologist; it was propagated by a very famous brand of blood cell counter manufacturer. It is a more sensitive parameter of anisocytosis than visual picture and has no subjective bias, provided it is expressed as SD and not CV. But by itself only it has no significant diagnostic value in isolation. Basic red cell parameters are still the backbones of morphological classification of anaemia; which is the first step in the algorithm to clinch the cause of anemia

Possibility of G6PD deficicency.

There are no pathophysiological reason in RDW decreasing in G6PD peoples in stable stages (i.e. in the absence of hemolytic crises). After hemolysis, reticulocytes having higher MCV than mature RBC increase in peripheral blood. If this increasing is significant enough to grow the average MCV, RDW decreases. So, there is no specific correlation with the G6PD deficiency but only with any serious hemolytic or hemorrhagic fact

Is this increases large enough to influence the absolute chracteristic profiles of WBC using some automated cell counters? as I was suggesting before!!!

Jerard

No disease is known in medicine