Haemoglobin blood test: What to expect

20th August, 2019 • 3 min read

Haemoglobin (or Hb) is found in red blood cells, and it helps carry oxygen around your body. If you don’t have enough haemoglobin then you will not have enough oxygen to function properly. This can cause a few different symptoms, including tiredness.

If your doctor suspects you have low levels of haemoglobin, also known as anemia, they may want to carry out a full blood count to measure the amount of haemoglobin in your blood.

How is a haemoglobin test carried out?

Usually a blood sample is taken by inserting a small needle into a vein in your arm, it can also be collected via a finger prick, or a heel prick in newborns.

How should I prepare for a haemoglobin blood test?

No specific preparation is required for the haemoglobin blood test, just make sure you have had enough to drink so that you are not dehydrated. Dehydration can make the results appear higher than they actually are.

What are normal values for a haemoglobin blood test?

In adults, a normal range for blood haemoglobin values is usually between 120 to 180 g/L (12 to 18 g/dL). However, reference ranges can vary from lab to lab and age, sex and ethnic origin can all affect haemoglobin levels. Speak to your doctor if you are worried about your results.

If you results are higher than normal this could be due to:

  • dehydration
  • overproduction of red blood cells in the bone marrow
  • severe lung disease

As well as other conditions.

If your results are lower than normal it may be due to:

When to worry about haemoglobin levels

You should see your doctor if you have symptoms of iron deficiency anemia. These include:

  • tiredness
  • feeling short of breath
  • heart palpitations
  • paler skin

Less common symptoms of iron deficiency anemia are:

Important: Our website provides useful information but is not a substitute for medical advice. You should always seek the advice of your doctor when making decisions about your health.