Blood Health

High Hemoglobin Levels: Is It Dangerous?

Written by Dr. Kks and medically reviewed by iCliniq medical review team.

Image: High Hemoglobin Levels: Is It Dangerous?

According to the conventional definition, it is considered as high hemoglobin when levels are more than 18.5 g/dL for men and 16.5 g/dL for women. High hemoglobin levels are associated with high hematocrit (also called as PCV) levels which are defined as greater than 50 % in men and greater than 45 % in women.

Polycythemia is the medical term for high hemoglobin. Polycythemia can be secondary or primary.

Primary polycythemia also called as polycythemia vera is a type of myeloproliferative disorders (the general term is blood cancer).

Secondary polycythemia is due to multifactorial reasons, few are as follows:

  1. Lung problems like asthma.
  2. Heart problems.
  3. Smoking.
  4. Dehydration.
  5. Living in high altitudes.
  6. Obesity.
  7. Stress.

So, with a good history, most cases can be grossly categorized into primary or secondary.

How to Differentiate Between Primary and Secondary?

  1. With the patient's medical history as mentioned above.
  2. Blood investigations like EPO (erythropoietin) levels, ABG (arterial blood gas analysis), specialized investigations like JAK-2 mutation analysis and bone marrow examination.


Polycythemia vera can be treated with a variety of modalities like phlebotomy (blood letting), low dose Aspirin, Hydroxyurea and in certain advanced cases Ruxolitinib.

In secondary cases, treatment is by addressing the underlying cause such as management of asthma, obesity, cessation of smoking, and other lifestyle changes.

As a final word of caution, I would like to say that not every case of high hemoglobin is blood cancer and not to get carried away or panic immediately. Please consult your general physician, and with proper history-taking, he will be able to guide you about what disease you are suffering from.

For more information consult a hematologist online -->

Last reviewed at: 13.May.2019



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Related Questions & Answers

Does a hematocrit of 49.2 indicate polycythemia?
Query: Hello doctor,My Hb is 15.8 but HCT is 49.2 and total RBC count is 5.63. What is the reason? I fear about polycythemia. Is it possible to reduce HCT?  Read Full »
Dr. Abdul Aziz Khan
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Answer: Hello, Welcome to If you are a smoker, then stop smoking. At this stage, secondary polycythemia is more common than primary and smoking is the most common reason for secondary. For further queries consult a hematologist online -->  Read Full »
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Answer: Hello, Welcome to The dehydration for prolonged duration can lead to high RBC count, high hematocrit and high hemoglobin level. But eight-hour fasting cannot lead to such findings. It is advisable to repeat your test after a few days. Until then, keep yourself well hydrated with lots ...  Read Full »
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Answer: Hello, Welcome to I have reviewed your query and below is my opinion. Your attached reports are suggestive of high RBC, hemoglobin, and HCT as per provided reference range in a laboratory report. So it is suggestive of polycythemia. It can be primary or secondary. Primary polycythemia s...  Read Full »

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