3.3c More on Too Many or Too Few RBC/Retics/Iron & Vits

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                 High Hematocrit/Polycythemia/Considerations  (Update, 25 Dec.. 2021).

   Varying degrees of high Hematocrit (Hct) should excite proportional anxious response. From 50 to 52% may be high normal, and will be associated with increased physical endurance, good for sports. From 53 to 55% is typical for low blood oxygen, chronic Carbon Monoxide poisoning or chronic lung disease or loss of lung tissue. Above 55% is blood or bone marrow disease, or developing cancer. Keep in mind we are discussing an apparently healthy person. A Hematocrit higher than 55% is a medical emergency. As Hct elevates in this range, risk of internal blood clot with complicating stroke and heart attack goes high. Also heart failure from the increased work for the heart to pump the extra weight of blood cells. And as prevention is easy (therapeutic blood-letting), there is no excuse for slow response.

          Low Hematocrit/Anemia/Considerations:

Anemia, arbitrarily, in men is Hct below 40%, in women below 37%. It needs analysis of the RBC count, the hemoglobin (Hgb) value and the Hct% to determine the RBC indices. Also useful are the reticulocyte count, the serum Fe (Iron) and vitamin B12/Folic Acid levels.

The RBC Indices are:

MCV, or Mean Corpuscular Volume, an RBC average size, in femto-liters (0.000000000000001, 10^-15 femto-).

MCH, or Mean Corpuscular Hemoglobin, amount of Hemoglobin in one RBC in picogram (0.000000000001, 10^-12 pico-).

MCHC, or Mean Corpuscular Hemoglobin Concentration, the percent (%), by weight, of Hemoglobin in an RBC.

   The MCV, MCH & MCHC are derivative, i.e., calculated from the RBC count, the hematocrit (Hct), and the hemoglobin (Hgb).

MCV is Hematocrit divided by Red Blood Cell Count.

MCH is Hemoglobin divided by Red Blood Cell Count.

MCHC is MCH divided by MCV.

Anemia and MCV: The anemia based on RBC size may be too large (MCV high; macrocytic), too small (MCV low;microcytic) or normal size RBC (MCV normal; normocytic range).

MCV high is due to deficiency Vitamin B12 or folic acid or it is a stage of bone marrow failure seen in old age or with cancer chemotherapy. Blood tests and a medical history will tell which.

MCV low is frequently due to Iron deficiency often from chronic blood loss. But another cause is Mediterranean (Cooley's) anemia, an inherited condition of abnormal hemoglobin that has no iron deficiency or no chronic blood loss but looks like them in its appearance of abnormally small, pale, poorly shaped RBC. 

With Cooley’s Anemia the serum iron is normal or high. (High from unnecessary, excessive iron that the Cooley’s patient is mistakenly given for iron deficiency.)

Normocytic Anemia is seen mostly in age over 65 and a sign of the mild bone marrow loss of aging. The aged will show Hct as low as 33%, as a normal adaptation. Such a mild to moderate low Hct gives less work for heart and less possibility of blood clogging up a coronary artery - good effects. And an Hct down to 33% does not badly affect one’s activity, especially in an oldster who normally has reduced physical activity. In such case, the serum iron, vitamin B12 and folic acid should all be checked because early deficiencies cause this type anemia. Also Retic. Count. (See below)

The red cell hemolyses (the RBC swells and breaks) and the leukemic anemias may be normocytic or macrocytic (a leukemia with microcytic anemia should be checked for blood loss ) and have other distinctive findings especially bone marrow test in case of leukemia.

Reticulocyte Count: The ”Retic” is a young RBC so named because center of the red blood cell shows small blue fragments giving reticule appearance. In good health, 0.5% to 1.5% RBCs are retics. But whenever there is increased destruction of RBC and normal nutrition and bone marrow, the retic percentage goes up due to too many young RBC made in bone marrow to replace the destroyed RBCs. So even with a normal RBC count and a normal Hct and a normal Hemoglobin, the finding of a high retic count means the RBC are being destroyed or lost and getting replaced by new RBC at increased rate. Patients with increased retic counts are either bleeding or having hemolysis (from immune reactions or infections like malaria). And, being alerted to that, leads to a search that may reveal peptic ulcer, cancer, immune disease or chronic malaria. But in vitamin or mineral deficiency or bone marrow failure anemia, the retic count is low or low normal even with the above-listed causes of high retic count. So the retic count is an important screening test and should be requested in any check of anemia.

                      Chapter continues in next, 3.3d. Click

3.3d Oxygen and CO2 in blood/Measurements/Effects