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What is a Red Blood Cell Count?

A Red Blood Cell (RBC) Count measures the number of red blood cells in your blood, crucial for carrying oxygen throughout your body. It's a key indicator of overall health, revealing conditions like anemia or polycythemia. Intrigued by how these tiny cells can reflect your well-being? Discover their secrets and what your count means for you—read on for a deeper dive.
A. B. Kelsey
A. B. Kelsey

The red blood cell (RBC) count is a blood test which determines the number of red blood cells, or erythrocytes, in a sample of blood. This test also evaluates the shape and the size of the red blood cells. All of this information is then used to determine the number of red blood cells per microliter of blood.

Red blood cell count values vary according to the age and the sex of a patient. The RBC count ranges from 4.2-5.0 million red blood cells per microliter of blood for women and 4.6-6.0 million for men. A normal red blood cell count for children is typically between 3.8 and 5.5 million red blood cells per volume.

A blood sample is required for a red blood cell count.
A blood sample is required for a red blood cell count.

This blood test is considered a very important indicator of a patient’s health. A low cell count might mean the patient has anemia, acute or chronic blood loss, malnutrition, chronic inflammation, or a number of nutritional deficiencies including iron, copper, vitamin B-12, or vitamin B-6. On the other hand, a higher than average RBC count, called polycythemia, can be a sign of congenital heart disease, pulmonary fibrosis, or renal problems. An increase of red blood cells can also happen naturally, though. People who live at high altitudes tend to have a higher-than-average RBC count, and smokers generally have a higher number of red blood cells than non-smokers.

The size of red blood cells usually falls within a range of 6 to 8 micrometers in random blood samples that have been analyzed by laboratory testing.
The size of red blood cells usually falls within a range of 6 to 8 micrometers in random blood samples that have been analyzed by laboratory testing.

An RBC count is almost always ordered as a part of the complete blood count (CBC), which determines the number of RBCs, white blood cells, and platelets. This blood test is also generally required for routine physicals and pre-surgical procedures. Patients with chronic anemia, hematological disorders, or chronic bleeding problems have their red blood cell count tested quite often so their physicians can keep track of any significant increase or decrease of red blood cells.

Regularly scheduled blood tests are needed in order to determine a patient's red blood cell count.
Regularly scheduled blood tests are needed in order to determine a patient's red blood cell count.

To get the sample needed for the RBC count, a patient’s blood is drawn from a vein, usually from the inside of the elbow or on the back of the hand. There are only slight physical risks in taking this blood test. The most common minor risks are feeling light-headed, fainting, and suffering through multiple punctures in order to locate a good vein.

Red blood cells are the most common type of cells in the blood, and are extremely important because they carry oxygen from the lungs to the body tissues. How much oxygen the body tissues receive depends on how many RBCs an individual has and how well they work. Thus, a routine blood test to determine the red blood cell count can help an individual stay healthy.

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Discussion Comments


I am four years out from Lynch Type II cancers and treatments (major surgeries, HDR, and chemo for my all else failed colon cancer) All three were synchronous primary.

Now my last CBC with differential came back flagged for my Hematocrit at 33.1 percent, my Hemaglobin was 11.4, BUN was 5mg/dl, TSH (OK-ish, guess) at .86 uU/ml. The doctor didn't give all the results to me. Should I be worried more than I am as I can't get out of bed now? Thanks for any help you may be able to give! Also, in case it matters, I have just turned 45 (female).


My sister got her rbc count back and it said it exceeds 10,000 over the normal. Is there any problem with this count?


I recently went for lab work. My results are 3.91 I don't understand it at all! Any advice?


My baby's hb is as low as 6.8. Please help me. My husband and I are carriers. What can we do?


My baby is eight months old and his red blood cell count is 2.9. What can I do to improve on that? I am worried.


I am 22 with and in normal health. My rbc is 2.8.Is it OK? Reply fast please.


I just turned 18 and I've been drinking iron for years and it's always been low. My iron level is 6.


@anon171633 - clearly doesn't know what they are talking about!


My Hb is 4.2 and platelets are 102. I've been admitted and transfused two pints packed cells two days ago. After the transfusion my Hb:6.5 Plt: 87 and total white is 2.7. My current result is Hb 6.9 plt: 92 and TWBC: 4.3.Doctor said I have pancytopenia and without doing a peripheral blood film, they want to do bone marrow. Is it OK?


I'd recommend all ignore a blood analyst's advice. It is rubbish, and has no scientific evidence to back the claims.


My wife has had very low red blood cell counts. Why, we do not know, but for the last two weeks she has been on an increased iron diet consisting of a cup of hot Bovril mid-morning instead of coffee, a glass of red wine with her dinner and satchel Spatone liquid iron supplement (no constipation) in the evening. She has shown a marked improvement on her latest blood test. Cheers, Roy. May be worth a try.


In one month, my RBC has dropped from 4.55 to 3.96, my eosinaphil count is 8.6, a fasting glucose of 80, blood pressure of 80/55, ANA positive 1:80, and recently diagnosed with Raynauds syndrome. For debilitating fatigue/headaches, what should I test for? My doctors are at a loss since it isn't mono, or anything "normal". I've had abdominal ultrasound, with normal results.


my 75 year old mom has polycythemia vera. her platelet count runs high and her rbc is currently low at 3.0. Her hematologist will not prescribe anything for this low rbc. She is tired and runs out of energy and now more short of breath.

She has another appointment with him this week. Her meds include hydroxyurea for her pv, coumadin, digoxin and synthroid. This is a difficult disease to manage. Any thoughts or questions that I should ask the dr. on her next appointment would be helpful.


anon133986, anon133222, anon90394: The way you build your blood is by consuming vast amounts of green fruits and vegetables. What I recommend is drinking 1 liter or 32oz of vegetable juice in the morning, followed by another in the afternoon and 4 vegetable smoothies during the day. (these are 16oz glasses)

To make the vegetable juice, use one whole celery, 1.5 large cucumbers and two apples. Chop and juice. Then, add one teaspoon of green powder - barley grass, wheatgrass, other blends, whatever. Over time, add in another tsp and try getting to four teaspoons per liter of drink.

To make the smoothie, take one-half cucumber and chop, one-half pink grapefruit and chop, two avocadoes chopped and blend with 1/2 cup of water in a blender. Then add in two large handfuls of spinach and blend, then add in one tablespoon of avocado/coconut/flax (or whatever) oil and blend. You can also juice beetroot (1 inch slice of raw) and add that in as well.

These smoothies and juices are strong blood building materials when combined with taking an iron supplement.

You can also take chlorella and spirulina capsules - start on 4 at lunchtime, 4 with breakfast and then build up to 15 at each over coming weeks. These also tone the bowel.

To help with energy, take a combined Calcium and Magnesium - 3 in the morning with breakfast, 3 at lunchtime.

You also need to be taking a reputable multivitamin, and probiotic.

With regard to diet, get off the crap food. Eat clean, meaning salads and fresh meats/chook/fish etc - no processed food, no coffee and no alcohol or fruit juice. These are the first things that destroy your blood and lead to anemia in the first place.

Good luck, and let me know how you get on!


I had 8-13 rbc as of today. is it dangerous or what? any suggestions please.


I have been anemic my whole life. recently my levels have been really low. we have done blood transfusions and iron pills but my body does not seem to accept it. I have 4-8 dizzy spells a day and have had a few fainting spells. The doctor recently told me that I'm in danger of strokes and even going into a coma. I have changed my diet and tried what i can but no luck. Any ideas? I am tired all the time and had to cut back on my hours at work.


I have pernicious anemia. I am on b12 injections for it. I tend to have a lot of kidney infections

and shortness of breath. Also I get a lot of pain and discomfort inside my rib cage but can't seem to determine exactly what's causing it. My red blood count was extremely low when last checked. Any ideas?


I have Acute Mylengous Leukemia and have finished my rounds of chemo and now my platelet count dropped in a weeks time from 175 to 71. It seems kind of strange since I got platelet transfusions about two weeks ago. The doc did an immediate bone marrow biopsy. Any idea of what may be happening?


As a general note, you are in total control of your own blood supply and how it functions, and therefore how you function.



@anon78357: See the first part of Post 9 to raise your rbc. Then follow the rest of Post 9.

Also, anyone who wants to keep their blood healthy and functioning needs to look after it with the right blood building materials.

anon84127: First, you also need dietary stabilising. You may have internal bleeding and if so, time to build your blood, get off the coffee/tea/unnecessary meds/sugars and other heavy acids and introduce blood building foods and drinks into your diet. It will take some work. You also need to be eating every two hours.

As for your doctor/surgeon, they usually cannot provide answers in detail because they do not know, or are reluctant to implicate themselves if they get it wrong. Tricky for them, tricky for you. You are doing the right thing though by keeping count of all your markers.


I am a disabled individual age 65. My white blood cells 1.1 hemoglobin 76 now, 46 and 62 in the past., 10 units of blood transfusion over a four week time frame, internal bleeding inability to function without transfusions.

Suspect a bad surgery, but doctors will not talk too much and attempt to diffuse situations. Any questions to ask Doctors, specialists?


my dad has a low blood count. I'm not sure which one it is but the doctors want to do an angiogram but they can't because of his blood level. he is also a diabetic which is almost uncontrollable. well, let's just say he has health issues. let me not forget his age, 71. What can we do to bring his blood count up?


B-12 and iron does not bring my red blood count up. It usually ranges around 9.6 to 10.6. I am taking Aranasep shots now but may have to quit due to the side effects. I was told some of my genes were disarranged and that is the reason why my count is low.

I stay tired and short of breath all the time. Will prednisone help or is there anything I can do to raise the count to 12 or 13?


anon58985: there are two ways to read RBC counts and I am not that familiar with the range of numbers that you have given. However, the technique and protocol is still the same. Anyone who is producing rbcs in the bone marrow is in survival. The red blood erythrocytes are actually produced in the small intestines.

Your daughter needs to be on a liquid feast consuming green foods and drinks every two hours to build her level of rbcs, give her much needed energy and level out her other blood markers.

anon62761: the iron supplements will not improve your red blood cell count. They are ultimately a band aid measure, which means that as soon as you stop taking them you will go back to original results.

Now for blood building, what you want to do is build your blood with appropriate blood building materials. They are green vegetables, salads, raw oils (2 tablespoons per day), vegetable juices (the green ones) and lightly steamed veggies. Green powders such as barley grass really work well and veggie juice plus powder will get your blood working pronto and bring back those markers within four weeks.

However, you must get off all blood destroying substances such as coffee, tea, alcohol, medications (unnecessary), sugars, acidic foods, fruit juices and fruits and really minimize your consumption of animal products and all dairy. It's only for a short time but beneficial in the long run.

The one thing that really helps is having an avocado shake - strong blood and nutrient builder. Broccoli and Cauliflower soup with fennel and other greens is also very powerful.

**Cauli and Broccoli Soup**

Take half large cauliflower and 1/2 large broccoli, chop and put into pan of water covering with some organic non yeast veggie stock. add fennel and other greens if you wish, simmer until soft (but not too soft) and blend.

good luck --Kate

**Avocado Shake**

2 medium avocados

1/2 cucumber – chopped

1/2 pink grapefruit – chopped

2 handfuls spinach

Hemp protein powder

2 tablespoons of ground flax seeds (optional)

3 tablespoons of your favorite oils

mint or basil


Put chopped cucumber, grapefruit and 1/2 cup water or almond milk in a blender, mint and blend

Add avocados, blend

Make a hole in the mixture, add oils and hemp seed protein, blend. Add in flax seeds at this point, and spinach. Blend til smooth.

Makes one pint and a little bit of shake.


My RBC is 3.76, and was 4.2 a month ago. Also, HGB and HCT are 0.5 below the low point of range. My doctor does not know what this is related to. Any suggestions as to what I should get tested for? Is it safe to take iron supplements to improve RBC (I am currently taking prescription vitamin D, as my vitamin D level is low at 15.)


My daughter has Auto-Immune Hemolytic Anemia. From what I understand of this illness is that her own body is turning against her and killing off her red blood cells faster then her bone marrow can make new ones. They treated her in the summer with prednisone (steroids) and it helped raised her levels to above 100. As I am reading things on the internet I get the 3.9, 4.5 and so on. I have no idea how to put my numbers into the 3.9 way. lol.

I am probably not making any sense here, but I ask the doctors questions and they all just speak to me in their language. I want to help my daughter maintain her levels and not be so worried all the time.

From what a doctor said is that a normal RBC for a woman is 140? When my daughter got first diagnosed she was under a third of what she should have been. She does not seem to go much higher then 110. Is there something I can do for her without using weight inducing steroids?


anon54835 - not too seriously, a woman's rbcc is usually around 4.4 - 4.7 and a mans a bit higher.

anon42551 - a low rbc is quite serious, it indicates damage to the intestinal villi and a serious over acidic condition in the blood and body tissues which will bring about many symptoms including debilitating ones. Yes, it is all related.

anon42207 - seriously, you want it to be much lower, and eat a lot of blood building materials that are salads, raw veges, oils etc, get off the coffee and alcohol, acids and blood destroyers.


My doctor made the statement today that my blood count was that of a man's. I'm a woman. How should I take this?


I had 3.9 rbc on my last test but my doctor didn't tell me it was low. I had a raised lipase of 800 and amylase of 178. Could all that be related?


I was recently hospitalized with a blood count of 6.4. how dangerous is this?


why are there a higher number of red blood cells in men than in women?


New red blood cells are being continually produced in the bone marrow. The life span of the cell is about four month.

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