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Blood Test Codes: 11 Common Abbreviations Explained

Medically approved by
Dr Earim Chaudry
Last updated
3rd June 2021

In 30 seconds

Medicine is full of technical terms and unfamiliar language. That’s to be expected. But for those that aren’t well-acquainted with blood test codes and abbreviations, that can all be a little overwhelming. Particularly when you are looking for important information about your health.

What are some of the most common blood test codes? You may have heard doctors refer to FBC, HbA1c, or PSA, LFT or TFT, ESR or INR, HDL or LDL. These are all types of blood tests that can help you and your doctor monitor a range of different health conditions. And there are many more.

If you are in any doubt about what your blood tests mean, talk to the professional that is administering the test. They should be able to clear up any uncertainties that you have.

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Introducing Blood Test Codes

It’s natural that we don’t always understand the things our doctors tell us – or the things we read online about our health. The world of health and medicine – and its language – is highly complex, specific, and technical, and is full of terms and expressions we don’t encounter much in everyday life.

However, when you are trying to understand your own health – or something like your blood test results – we get that all of this can be a little frustrating. Sometimes you just want clarity. It is your health, after all.

That’s why we’re here – to lead you through the specialised language of medicine. In this article, we’re looking at some of the common blood test codes and abbreviations that you should understand. Because understanding your blood tests means understanding the state of your well-being too.

Some Blood Test Codes and Abbreviations You Need to Know

Blood tests are a crucial window onto your health. But while your doctor – or whoever administers your test – should explain to you what they all mean, these tests are not exactly the simplest things in the world. Instead, they engage with and monitor the very smallest, most specific biological processes in your body – or all the things that go to make up that thing called your health.

So, here are some of the blood test codes and abbreviations that you might encounter. We hope that they help you understand what’s going on in your body that little bit better.

ALT and AST – Alanine Aminotransferase and Aspartate Aminotransferase

Big words to start off with: the ALT and AST. These are abbreviations for the names of two enzymes that are produced by the liver. ALT helps convert proteins into energy, while AST breaks down amino acids. When there is a problem in your liver, these enzymes enter your bloodstream in greater quantities. As a result, a high level of ALT or AST in your bloodstream may signal liver disease or damage.

You may also hear about an LFT, or a liver function test. This is the general name for the tests which check the condition of your liver – but it usually includes the tests for ALT and AST.

CRP – C-Reactive Protein

C-reactive protein is another protein that is produced by the liver. However, this one is released into the bloodstream as a result of inflammation. You might have a CRP test when doctors suspect you have inflammation – such as the result of arthritis, heart disease, or a chronic inflammatory disease.

ESR – Erythrocyte Sedimentation Rate

An ESR test is a particular type of test for inflammation that measures how quickly red blood cells settle – or sediment – at the bottom of a test tube. Usually, these settle quite slowly – and if they do so more quickly than usual, it can signal inflammation.

FBC – Full Blood Count

Sometimes known as the CBC (complete blood count), the FBC is the most general analysis of your blood. It looks at your red blood cells (RBC), your white blood cells (WBC), your number of platelets, the concentration of haemoglobin, and the haematocrit (HTC).

HbA1c – Haemoglobin A1c

HbA1c is the name of a blood test that monitors blood glucose levels. Specifically, it refers to the amount of glycated haemoglobin (or hemoglobin) – or the number of compounds of glucose and haemoglobin. It’s a particularly crucial test for diabetes, or those at risk of diabetes.

‘Hb’ is just shorthand for haemoglobin. And that ‘A1c’? It’s a specific type of haemoglobin that is measured.

HDL / LDL – High-Density Lipoprotein / Low-Density Lipoprotein.

You may have heard that there is such thing as ‘good’ and ‘bad’ cholesterol. Generally speaking, HDL is the ‘good’ one and LDL the ‘bad’. 

HDL is a handy lipoprotein (a specific form of lipid, triglyceride, or fat), because it transports other types of cholesterol back to the liver where it can be processed and removed from the body. LDL, on the other hand, collects in the walls of your blood vessels. 

INR – International Normalised Ratio

The International Normalised Ratio test measures the time it takes for your blood to clot. This is important because it can be a problem if your blood is clotting too fast or too slow (particularly if it clots inside your blood vessels). 

You might take the INR test if you are on medication that thins your blood, such as warfarin.

PSA – Prostate Specific Antigen

Another type of test, the PSA looks at the health and activity of your prostate gland. If your PSA level is too high, it might be a sign of prostate cancer (but it can also be due to other things, such as an infection). These tests are not always perfect, either – so, your PSA test results will probably be used in combination with other tests too.

TSH – Thyroid Stimulating Hormone

TSH is a type of hormone that is measured during the thyroid function test (TFT), along with thyroxine and triiodothyronine, sometimes known as free T4 and free T3 respectively. Testing these hormones help to see if your thyroid gland is healthy – or whether it may be inflamed, have a lump, or be overactive. While it is not well known, the thyroid is important in controlling the body’s metabolism and growth.

Shop Our Blood Test Kits

Easy at-home sampling, in depth health results

Take control of your health with the UK’s leading at-home blood tests. Just a simple finger-prick to unlock all your health levels.


Compete blood test
Testosterone blood test

Key Takeaways

Blood tests are complex things. Yet, the terminology of blood test codes and abbreviations shouldn’t put you off trying to understand what’s going on with your health. Rather, when it comes to health, knowledge is power: understanding your health enables you to make the right lifestyle decisions.

While we've ensured that everything you read on the Health Centre is medically reviewed and approved, information presented here is not intended to be a substitute for professional medical advice, diagnosis, or treatment. It should never be relied upon for specific medical advice. If you have any questions or concerns, please talk to your doctor.

Further reading

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