RBC count blood test: normal range explained

RBC count measures the number of red blood cells, also called erythrocytes, in your blood. Red cells are made in the bone marrow and carry haemoglobin, the iron-rich protein that moves oxygen from your lungs to every cell in your body.

The count is printed in millions of cells per microlitre, written as million/µL, million/cumm or 10^6/µL on Indian reports; a value of 4.8 means 4.8 million cells in each microlitre. It is almost always part of a complete blood count (CBC) with haemoglobin and the red cell indices.

Doctors order an RBC count to help diagnose anaemia and other disorders of red blood cells, during a routine check-up, during treatment that affects blood counts such as chemotherapy, and to monitor conditions such as chronic kidney disease. MedlinePlus notes that a count higher or lower than normal is often the first sign of an illness.

Symptoms that prompt the test include shortness of breath, weakness or tiredness, headache, dizziness and pale skin for a low count, and headache, dizziness and vision problems for a high one. NHLBI lists the RBC count among the CBC values used to look for anaemia.

An RBC count moves with where you live, how much water you drank and several medicines.

• Living at a high altitude raises the count for several weeks, because less oxygen is available.
• Dehydration and cigarette smoking are listed causes of a high count; pregnancy is a listed cause of a low count.
• Medicines can raise it (anabolic steroids, erythropoietin, gentamicin, testosterone) or lower it (chemotherapy, some antibiotics, NSAIDs, methyldopa, quinidine).
• Over-hydration lowers the count by diluting the blood.
• Too little iron, copper, folic acid, vitamin B6 or vitamin B12 lowers it over time.
• Tell your doctor about every medicine you use, because Testing.com says some can raise or lower the count.