Packed Cells Volume (PCV) Practical Physiology 5th Lab. dlerqader74@yahoo.com

Packed Cells Volume PCV Measurement of hematocrit or packed cell volume is the most accurate and simplest of all tests in clinical hematology for detecting the presence and degree of anemia or polycythemia. In comparison, hemoglobin estimation is less accurate, and RBC count far less accurate.

What is effect of high hematocrit? Increase in hematocrit increase the viscosity of blood which leads to an increase in peripheral resistance, and thus the blood pressure.

Normal values of PCV At Birth 56 ± 10 %. Adults male 47 ± 5 %. Adult female 42 ± 5 %.

Increased in PCV is seen in New born, high altitude, hypoxia, due to heart or lung disease, polycythemia.

Decreased in PCV is seen in All type of anemia Pregnancy

Blood Indices What the MCV Means MCV measures the average size of the red blood cells. The MCV rises when red blood cells are larger than normal (macrocytic). This condition is called macrocytic anemia. The MCV falls when red blood cells are smaller than normal (microcytic). This condition is called microcytic anemia.

When MCV values are normal, the red blood cells are normal in size When MCV values are normal, the red blood cells are normal in size. They are called normocytic. However, a person with normocytic red blood cells can still be anemic when there are too few red blood cells or when other RBC indices are abnormal. This is called normocytic anemia.

What the MCH Means MCH measures the average amount of hemoglobin in a red blood cell. When MCH values are high, the red blood cells are called hyperchromic. The red blood cells will be deeper in color. This condition is called hyperchromic anemia. When MCH values are low, the red blood cells are called hypochromic. The red blood cells will be paler in color. This condition is called hypochromic anemia.

When MCH values are normal, the red blood cells are normal in color When MCH values are normal, the red blood cells are normal in color. They are called normochromic.

What the MCHC Means The MCHC is the average concentration of hemoglobin inside a red blood cell.  The MCHC is Hgb divided by the Hct. So MCHC = Hgb/Hct. When the MCHC is higher than normal, then hemoglobin is abnormally concentrated in red blood cells. The red blood cells will be deeper in color. This is called hyperchromia.

When the MCHC is lower than normal, hemoglobin is abnormally diluted in the red blood cells. The red blood cells will be paler in color. This condition is called hypochromic anemia. When the hemoglobin concentration is normal, the MCHC is normal.

Normal Value MCV: 80 to 100 femtoliter MCH: 27 to 31 picograms/cell MCHC: 32 to 36 grams/deciliter