A targeted blood test designed to investigate
some of the common physical causes of persistent
tiredness and fatigue, including anaemia,
thyroid problems, vitamin deficiency,
diabetes and kidney health.
Persistent tiredness can have many possible
causes. The Fatigue Screen brings together
several commonly assessed blood markers
in one targeted panel.
The test looks at blood count, iron status,
thyroid function, vitamins, kidney function
and long-term blood sugar levels.
It can provide useful information when you
want to investigate whether a measurable
physical factor may be contributing to
ongoing tiredness or reduced energy.
Targeted testing
What does this test look at?
Blood health
A Full Blood Count helps assess
red blood cells, haemoglobin,
white blood cells and platelets.
Iron status
Iron markers can help assess
iron stores and iron availability,
including possible iron deficiency.
Thyroid function
TSH and Free T4 assess thyroid
function, which can be relevant
when investigating fatigue.
Vitamins
Vitamin B12, folate and Vitamin D
are included to identify common
nutritional deficiencies.
Kidney function
Kidney function markers provide
information about filtration,
hydration and electrolyte balance.
Blood sugar
HbA1c provides an indication of
average blood glucose levels over
the previous few months.
What's included
Your biomarkers
The Fatigue Screen includes a range of blood
markers that can help assess some common
physical factors associated with persistent
tiredness and reduced energy.
Haemoglobin
Haemoglobin is the iron-containing protein found within red blood cells that carries oxygen from your lungs to every tissue in your body. Measuring haemoglobin is one of the most important ways to assess your body's ability to deliver oxygen efficiently. Low haemoglobin levels may indicate anaemia caused by various conditions.
Red Blood Cell (RBC) Count
This test measures the number of red blood cells circulating in your bloodstream and helps assess your body's oxygen-carrying capacity.
Haematocrit (HCT)
Haematocrit measures the percentage of your blood that is made up of red blood cells.
Mean Corpuscular Volume (MCV)
MCV measures the average size of your red blood cells. It is particularly useful when investigating the cause of anaemia, as different deficiencies affect red blood cell size in different ways.
Mean Corpuscular Hemoglobin (MCH)
MCH measures the average amount of haemoglobin contained within each red blood cell. It helps assess how effectively your red blood cells are able to carry oxygen around the body.
Mean Corpuscular Hemoglobin Concentration (MCHC)
MCHC measures the average concentration of haemoglobin within your red blood cells.
Red Cell Distribution Width (RDW)
RDW measures the variation in the size of your red blood cells. Healthy red blood cells are usually similar in size, whereas greater variation may indicate that new and older blood cells differ significantly.
Platelets
Platelets are small blood cells that play a vital role in helping your blood clot after an injury, preventing excessive bleeding. Measuring your platelet count can help identify clotting disorders, inflammation, infection and conditions affecting the bone marrow.
Mean Platelet Volume (MPV)
MPV measures the average size of your platelets.
White Blood Cell (WBC) Count
White blood cells are a key part of your immune system and help protect your body against infections and disease. This test measures the total number of white blood cells circulating in your bloodstream. Raised levels commonly occur during infections or inflammation, while lower levels may result from certain viral infections, medications, autoimmune conditions or bone marrow disorders.
Neutrophils
Neutrophils are the most abundant type of white blood cell and form your body's first line of defence against bacterial infections. Increased neutrophil levels are commonly seen with bacterial infections, inflammation, physical stress and corticosteroid treatment. Low levels may increase your susceptibility to infection and can occur with some viral illnesses, medications or bone marrow disorders.
Lymphocytes
Lymphocytes are specialised white blood cells that help your immune system recognise and fight viruses, bacteria and other harmful organisms. They also play an important role in producing antibodies and developing long-term immunity. Abnormal lymphocyte levels may occur with viral infections, autoimmune diseases, chronic infections and certain blood disorders.
Monocytes
Monocytes are white blood cells that help remove damaged cells, bacteria and other foreign material from the body. They also support tissue repair following infection or inflammation.
Eosinophils
Eosinophils are white blood cells involved in allergic reactions and defending the body against parasitic infections. Elevated levels are commonly associated with allergies, asthma, eczema and certain parasitic infections.
Basophils
Basophils are the least common type of white blood cell and contribute to allergic and inflammatory responses by releasing substances such as histamine. Although abnormalities are uncommon, raised basophil levels may be associated with allergic conditions, chronic inflammation or certain bone marrow disorders.
Ferritin
Ferritin is the body's main iron storage protein and provides the most accurate indication of your iron stores. Iron is essential for producing healthy red blood cells, transporting oxygen around the body and supporting normal energy production. Low ferritin levels are one of the earliest signs of iron deficiency and may contribute to tiredness, weakness, poor concentration, headaches, restless legs and hair loss, even before anaemia develops. Raised ferritin levels may occur with inflammation, liver disease, excessive iron storage disorders such as haemochromatosis, alcohol excess or certain chronic medical conditions. Ferritin should always be interpreted alongside other iron markers to provide a complete assessment of your iron status.
Serum Iron
Serum iron measures the amount of iron circulating in your bloodstream that is available to produce haemoglobin and support normal body function. Iron levels naturally fluctuate throughout the day and can be influenced by diet, illness and recent iron supplementation. For this reason, serum iron is usually interpreted together with ferritin, transferrin and transferrin saturation to provide a more accurate picture of your body's iron balance. Low levels may suggest iron deficiency, while raised levels can occur with iron overload disorders or liver disease.
Transferrin
Transferrin is a protein produced by the liver that transports iron around your body to where it is needed, particularly for the production of red blood cells. When your iron stores are low, your body often produces more transferrin to maximise iron transport. Conversely, transferrin levels may fall in chronic illness, liver disease or malnutrition. Measuring transferrin alongside ferritin and serum iron helps distinguish between different causes of iron deficiency and iron overload.
Total Iron Binding Capacity (TIBC)
Total Iron Binding Capacity (TIBC) measures the maximum amount of iron that transferrin can carry in the bloodstream. It provides an indirect assessment of transferrin levels and helps determine whether your body has sufficient iron stores. TIBC is often increased in iron deficiency as your body attempts to transport more iron, while lower levels may occur with chronic inflammation, liver disease or iron overload conditions.
Unsaturated Iron Binding Capacity (UIBC)
UIBC measures the amount of transferrin that is available to bind additional iron. It provides further information about your body's ability to transport iron and is commonly interpreted alongside serum iron and TIBC. Higher UIBC values may indicate iron deficiency, whereas lower values can be associated with iron overload.
Transferrin Saturation
Transferrin saturation calculates the percentage of transferrin that is carrying iron. It is one of the most useful markers for assessing how much iron is immediately available for use by your body. Low transferrin saturation commonly suggests iron deficiency, while persistently raised levels may indicate iron overload disorders such as hereditary haemochromatosis. This marker is particularly valuable when interpreted alongside ferritin.
Creatinine
Creatinine is a waste product produced naturally by your muscles as part of normal daily activity. Healthy kidneys remove creatinine from the blood and excrete it in urine, making it one of the most widely used markers of kidney function. Raised creatinine levels may indicate reduced kidney function, although levels can also be influenced by muscle mass, dehydration, certain medications and recent strenuous exercise. Measuring creatinine alongside eGFR provides a more complete assessment of kidney health.
Estimated Glomerular Filtration Rate (eGFR)
eGFR estimates how efficiently your kidneys filter waste products and excess fluid from your blood. It is calculated using your creatinine level together with factors such as your age and sex. eGFR is one of the most important indicators of kidney function and is commonly used to detect and monitor chronic kidney disease. A persistently reduced eGFR may suggest impaired kidney function and should always be interpreted alongside your clinical history and other blood test results.
Urea
Urea is a waste product formed when your body breaks down protein. It is transported in the bloodstream and removed by the kidneys. Measuring urea helps assess kidney function, hydration status and protein metabolism.
Sodium
Sodium is an essential electrolyte that helps regulate fluid balance, blood pressure, nerve signalling and muscle function. Your kidneys and hormones work together to keep sodium levels within a narrow range. Abnormal sodium levels may occur with dehydration, kidney disease, heart failure, hormonal disorders or certain medications, and can affect normal brain and muscle function.
Chloride
Chloride is an electrolyte that works alongside sodium and potassium to help maintain fluid balance, blood pressure and the body's acid-base balance. Abnormal chloride levels often occur alongside changes in other electrolytes and may be associated with dehydration, kidney disease, prolonged vomiting, diarrhoea or metabolic disorders.
Thyroid Stimulating Hormone (TSH)
Thyroid Stimulating Hormone (TSH) is produced by the pituitary gland and controls how much thyroid hormone your thyroid gland produces. It is usually the earliest marker to become abnormal when thyroid function changes, making it one of the most sensitive tests for assessing thyroid health. Raised TSH levels commonly suggest an underactive thyroid (hypothyroidism), while low levels may indicate an overactive thyroid (hyperthyroidism). As thyroid hormones regulate metabolism, energy production and many bodily functions, thyroid disorders may contribute to symptoms including fatigue, weight changes, sensitivity to temperature, mood changes, dry skin and alterations in heart rate.
Free Thyroxine (T4)
Free T4 is one of the two main hormones produced by your thyroid gland and plays a central role in regulating metabolism, body temperature, energy production and growth. Measuring Free T4 alongside TSH helps determine whether your thyroid is functioning normally and assists in diagnosing both underactive and overactive thyroid conditions. Abnormal Free T4 levels should always be interpreted alongside TSH to provide the most accurate assessment of thyroid function.
Free Triiodothyronine (T3)
Free T3 is the biologically active thyroid hormone responsible for regulating many of your body's metabolic processes. It influences energy levels, heart function, digestion, body temperature and the rate at which your body uses energy. Measuring Free T3 can provide additional information when investigating thyroid disorders, particularly when symptoms persist despite normal TSH or Free T4 levels or when hyperthyroidism is suspected.
HbA1c
HbA1c (glycated haemoglobin) measures your average blood glucose level over approximately the previous 2 to 3 months by assessing how much glucose has attached to your red blood cells. Unlike a single glucose reading, HbA1c provides a long-term picture of blood sugar control and is regarded as the gold standard test for diagnosing and monitoring diabetes. Raised HbA1c levels may indicate pre-diabetes or diabetes and, if left untreated, are associated with an increased risk of complications including heart disease, kidney disease, nerve damage and diabetic eye disease. Monitoring HbA1c can also help assess how well diabetes treatment and lifestyle changes are working over time.
Vitamin D (25-OH Vitamin D)
Vitamin D plays a vital role in maintaining healthy bones, teeth and muscles by helping your body absorb calcium and phosphate. It also supports normal immune function and contributes to muscle strength and general wellbeing. Low vitamin D levels are common in the UK and may contribute to tiredness, muscle weakness, bone pain and an increased risk of fractures. Measuring vitamin D helps identify deficiency and monitor response to supplementation.
Folate
Folate is required for healthy red blood cell production, DNA synthesis and normal cell growth. It works closely with vitamin B12 and is particularly important during pregnancy to support normal fetal development. Low folate levels may contribute to fatigue, anaemia and poor cell regeneration. Measuring folate alongside vitamin B12 helps investigate nutritional deficiencies and the causes of macrocytic anaemia.
Active Vitamin B12 (Holotranscobalamin)
Vitamin B12 is essential for healthy red blood cell production, normal nerve function and DNA synthesis. Low vitamin B12 levels may lead to fatigue, weakness, poor concentration, memory problems, numbness or tingling in the hands and feet, and anaemia. Deficiency may develop due to poor dietary intake, reduced absorption, certain medications or autoimmune conditions such as pernicious anaemia. Active Vitamin B12 measures the proportion of vitamin B12 that is immediately available for your body's cells to use. It may detect vitamin B12 deficiency earlier than total vitamin B12 in some individuals and can provide additional information when investigating symptoms suggestive of deficiency despite apparently normal total B12 levels.
Important Pre-Test Information
Iron Supplements
If you are taking oral iron supplements,
please inform our team as this may affect
some iron parameters.
Biotin
Please stop taking Biotin supplements 7 days
before the test, as they can interfere with
certain laboratory results, including thyroid
tests.
Thyroxine / Levothyroxine
If you take thyroid replacement medication,
your blood sample should ideally be collected
before taking your morning dose.
Is this test right for me?
A targeted fatigue health check
This package may be suitable if you have been
experiencing ongoing tiredness or reduced energy
and want to investigate some common physical
factors that may contribute to fatigue.
Persistent tiredness or fatigue
Checking for possible nutritional deficiencies
Assessing thyroid and blood health
Checking blood sugar and kidney function
Simple process
What happens next?
01
Book
Choose your appointment and
complete your booking online.
02
Get tested
Attend the clinic or arrange
home blood collection.
03
Receive results
Your blood results are reviewed
and provided to you.
Prefer to have your blood taken at home?
Our nationwide home blood collection
service is available for this test.
Fatigue can have many possible causes. Blood testing
can help assess some common physical factors including
anaemia, iron deficiency, thyroid problems, vitamin
deficiency, abnormal blood sugar and kidney function.
No. You can book a private blood test directly
with Prime Life Diagnostics without a GP referral.
This panel does not routinely require fasting.
You should follow any specific preparation
instructions provided before your appointment.
Yes. This test can be combined with our nationwide
home blood collection service.
Most blood test results are available within
24–72 hours, although some tests may take longer.
Results are reviewed as part of Prime Life
Diagnostics' doctor-led service.
