What is the normal range of erythrocytes per cubic millimeter?

What is the normal range of erythrocytes per cubic millimeter?

• A. 4.2-6.2 million per cubic mm.
• B. 1.0-2.0 million per cubic mm.
• C. 8.0-9.0 million per cubic mm.
• D. 10-12 million per cubic mm.

Answer: (A)

The main concept is knowing the usual concentration of red blood cells in blood, measured in millions per cubic millimeter. For healthy adults, the normal range is about 4.2 to 6.2 million erythrocytes per cubic millimeter. The unit is the same as per microliter, since one microliter equals one cubic millimeter, which is why we see the numbers expressed as millions per cubic millimeter. This range reflects typical oxygen-carrying capacity. Values that are much lower, around 1–2 million, would indicate anemia with reduced oxygen delivery. Values well above 6 million, such as 8–9 or 10–12 million, can occur with dehydration or polycythemia and are not considered normal.

The main concept is knowing the usual concentration of red blood cells in blood, measured in millions per cubic millimeter. For healthy adults, the normal range is about 4.2 to 6.2 million erythrocytes per cubic millimeter. The unit is the same as per microliter, since one microliter equals one cubic millimeter, which is why we see the numbers expressed as millions per cubic millimeter. This range reflects typical oxygen-carrying capacity. Values that are much lower, around 1–2 million, would indicate anemia with reduced oxygen delivery. Values well above 6 million, such as 8–9 or 10–12 million, can occur with dehydration or polycythemia and are not considered normal.