Advanced Tiredness and Fatigue Blood Test, from our experts to you.
Dr Sam Rodgers MBBS, MRCGP

Chief Medical Officer meet our doctors

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What is the
Advanced Tiredness and Fatigue Blood Test?

Feeling tired is one of the most common reasons people visit their doctor, but sometimes finding out the reasons for your symptoms can be a journey of trial and error. Often, fatigue is caused by anaemia, either from iron deficiency or low levels of B vitamins, which are essential to creating normal red blood cells.

Our Advanced Tiredness and Fatigue Blood Test includes all of the tests in our Tiredness and Fatigue Blood Test plus a full blood count (FBC), where we look at the number, size, and shape of your red blood cells. If your red blood cells are abnormal, it affects their ability to transport oxygen around your body, a common cause of fatigue.

What can I learn
from this test?

Our advanced fatigue profile aims to get to the cause of low energy levels. With it, you can check your iron status and active vitamin B12 levels, your red blood cells to make sure that they show no signs of anaemia, and white blood cells to check that infection or inflammation is not contributing to your symptoms. We also check for vitamin D deficiency, which is a very common cause of low energy and aches and pains and other causes of fatigue like diabetes and an underactive thyroid.

What can I learn
from this test?

As this is an advanced test with added markers, your blood sample will be taken from a vein in your arm (a venous sample) rather than collected from a finger-prick collection. You can choose a nurse to collect your sample from you at home or at one of our clinics, or you can make your own arrangements. A venous blood test allows us to check more markers and include an FBC, where we look at the number, size, and shape of your red blood cells.

What's included?

Clotting status
Iron status
Red blood cells
Thyroid hormones
White blood cells
Select profile for more information

Platelet count Platelets or clotting cells are the smallest type of blood cell. They are formed in the bone marrow and are important in blood clotting. When bleeding occurs, the platelets swell, clump together and form a sticky plug (a clot) which helps stop the bleeding.
MPV MPV, or Mean Platelet Volume, is a measurement of the average size of your platelets. Platelets are fragmented cells within the blood that aid the process of clot formation. MPV provides an indication of platelet production in your bone marrow.
HbA1c Haemoglobin A1c (HbA1c), also known as glycated haemoglobin, is a longer term measure of glucose levels in your blood than a simple blood glucose test. Glucose attaches itself to the haemoglobin in your red blood cells, and as your cells live for around 12-16 weeks, it gives us a good indication of the average level of sugar in your blood over a 3 month period.
hs - CRP C-Reactive Protein (CRP) is an inflammation marker used to assess whether there is inflammation in the body - it does not identify where the inflammation is located. High Sensitivity CRP (CRP-hs) is a test used to detect low-level inflammation thought to damage blood vessels which can lead to a heart attack or stroke. When you suffer a serious injury or infection you experience significant inflammation around the site of injury - such as the swelling around a twisted ankle. Any injury like this will cause your CRP-hs to rise.
Iron Iron is a mineral that is essential for life. It is a component of haemoglobin, a protein in our red blood cells that is responsible for transporting oxygen around our body. If we don't have enough iron, our haemoglobin levels fall and we can't get sufficient oxygen to our cells. This can cause symptoms which include fatigue, dizziness, and shortness of breath. Serum iron is a very transient reading and can be influenced by the amount of iron-rich food in your diet in the days before your blood test. For this reason, iron is rarely looked at on its own, and is interpreted alongside other markers in an iron status test.
TIBC Total iron-binding capacity (TIBC) is a measure of the ability of your body to efficiently carry iron through the blood.
Transferrin saturation Transferrin is made in the liver and is the major protein in the blood which binds to iron and transports it round the body. This test measures how much this protein is 'saturated' by iron.
Ferritin Ferritin is a protein which stores iron in your cells and tissues. Usually, the body incorporates iron into haemoglobin to be transported around the body, but when it has a surplus, it stores the remaining iron in ferritin for later use. Measuring ferritin levels gives us a good indication of the amount of iron stored in your body.
Haemoglobin Haemoglobin is a protein in red blood cells which carries oxygen around the body and gives the blood its red colour. This test measures the amount of haemoglobin in the blood and is a good measure of the blood's ability to carry oxygen around the body.
Haematocrit HCT (haematocrit) measures the amount of space (volume) within the blood that is taken up by red blood cells.
Red cell count Red Blood Cell (RBC) Count analyses the number of red blood cells in the blood. Red blood cells carry oxygen from the lungs to the rest of the body, where it can be used to fuel energy processes such as movement and respiration. They also carry carbon dioxide produced from cells back to the lungs so that it can be exhaled.
MCV MCV (mean corpuscular volume) reflects the average size of your red blood cells. This is important to measure, as it can indicate how much oxygen your cells are likely to be transporting around the body.
MCH MCH (mean corpuscular haemoglobin) measures the average amount of haemoglobin contained in one of your red blood cells.
MCHC MCHC (mean corpuscular haemoglobin concentration) is the average concentration of haemoglobin in your red blood cells. Haemoglobin is a molecule which allows red blood cells to transport oxygen around the body.
RDW Red blood cell distribution width (RDW) indicates whether your red blood cells are all the same size, or different sizes or shapes. Normally cells are fairly uniform both in size and in shape, but some blood disorders may cause your red blood cells to form in abnormal sizes. This test measures the difference between the largest and the smallest red blood cell.
TSH Thyroid stimulating hormone (TSH) is produced in the pituitary gland in order to regulate the production of thyroid hormones thyroxine (T4) and triiodothyronine (T3) by the thyroid gland. If thyroid hormones in the blood are low, then more TSH is produced to stimulate the thyroid gland to produce more of them. If thyroid hormone levels are high, then the pituitary produces less TSH to slow the production of thyroid hormones. If TSH is too high or too low, it normally signifies that there is a problem with the thyroid gland which is causing it to under or over produce thyroid hormones. Sometimes a disorder of the pituitary gland can also cause abnormal TSH levels.
Free thyroxine Thyroxine (T4) is one of two hormones produced by the thyroid gland. It works to speed up the rate of your metabolism. Most T4 is bound to carrier proteins in the blood - it is only the free, or unbound, T4 that is active in the body, which is measured in this test. Free T4 is the less active of the two main thyroid hormones. To have an impact on your cells it needs to convert to the more active T3 when your body needs it.
Folate - serum Folate is a B vitamin which acts as a coenzyme in the metabolism of amino acids. It is also vital for the synthesis of purines and pyrimidines which are essential for DNA synthesis and red cell formation. Folate is also especially important during the first trimester of pregnancy so if you are thinking of becoming pregnant it is important to make sure your folate levels are normal.
Vitamin B12 - active Vitamin B12 is important for production of red blood cells which carry oxygen around the body. B12 is also involved in metabolism and the nervous system and prolonged lack of vitamin B12 may cause nerve damage. Although Vitamin B12 is almost entirely found in animal-based foods, many vegetarian and vegan products, especially plant milks are now fortified with Vitamin B12.
Vitamin D Although called a vitamin, vitamin D is actually a hormone which is activated by sunshine on your skin. Vitamin D is essential for bone strength as it helps your intestines absorb calcium. However, it is thought that vitamin D also plays an important role in immune function, as well as in many chronic diseases and mental health. Many people in the UK have low levels of vitamin D with symptoms including muscle weakness, mood swings and fatigue. People who have dark skin, as well as those who don't spend much time outdoors are particularly at risk of low vitamin D. Small amounts of vitamin D can be obtained from food, especially oily fish, eggs and any food which has been fortified with vitamin D. If you are deficient in vitamin D you are unlikely to be able to improve your levels by food alone.
White cell count White Blood Cell (WBC) Count measures the number of white blood cells in the blood. White blood cells are key to your body's immune system. They fight infections and protect your body from foreign invaders such as harmful germs and bacteria. Additionally, they produce many antibodies and memory cells to protect you from further infections with the same germ.
Neutrophils Neutrophils are the most abundant type of white blood cell in the body and are responsible for helping your body fight infection. When a germ is initially detected by the body, neutrophils are the defence system which go out and attack the germ before any of your other white blood cells. When neutrophils are low you can be more vulnerable to illness and infection.
Lymphocytes Lymphocytes are a type of white blood cell which fight bacterial and viral infections. They are the subset of white blood cells involved in the more specific response to infections, which can identify and differentiate between different foreign organisms that enter the body. As well as fighting infection, they produce antibodies and memory cells to help to prevent future infections from the same germ. Lymphocytes include T cells, B cells and natural killer cells.
Monocytes Monocytes are a type of white blood cell that surround and destroy germs and dead or damaged cells from the blood. The heat and swelling that you feel when a body part is inflamed, for example after a cut on your finger, is caused by the activities of these cells.
Eosinophils Eosinophils are a type of white blood cell that are responsible for removing parasitic infections and regulating inflammation to mark an infected site. They also play a role in allergy and in asthma.
Basophils Basophils are a type of white blood cell that protect your body from bacteria and parasites such as ticks. They also play a role in allergic reactions.

How to prepare
for your test

Special instructions

Prepare for your Advanced Tiredness and Fatigue Blood Test by following these instructions. Please take your sample before 10am. Take this test when any symptoms of short-term illness have settled. You should take this test before you take any medication or vitamin/mineral supplements. Do not take biotin supplements for two days before this test, discuss this with your doctor if it is prescribed. Do not take vitamin B12 for two weeks prior to this test. If your B12 is prescribed ask your doctor whether to stop.

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