Understanding Your Blood Test Results | UK Patient Guide

May 3, 2026

From routine screening to comprehensive and specialised profiles, blood tests offer valuable insights into your overall health. Private blood tests often provide faster turnaround times, while NHS blood test results may take several days or, in some cases, a few weeks, depending on the test and the GP review process.

Waiting a long time for results and interpretation can feel stressful, which is why many people try to understand what their blood test results mean on their own. This guide explains common markers found on a blood test report, what normal ranges mean for UK patients, and what each result may suggest about your health, helping you understand your report with greater confidence.

Abbreviations Generally Used in Blood Test Results

mL	milliliter
mmol/L	Millimoles per liter
mg/dL	Milligrams per deciliter
ng/mL	Nanograms per milliliter
pg	Picograms - one-trillionth of a gram
IU/L	International units per liter
mEq/L	Milliequivalent per liter
cmm	Cells per cubic millimetre
fL	Femtoliter - a fraction of one-millionth of a litre

Common Blood Tests, Reference Ranges, and Results

Before looking at reference ranges and the type of feedback a doctor may provide on a blood test report, it is important to understand that results can vary depending on factors such as age, sex, medical history, and current symptoms. For this reason, it is always best to seek expert medical advice and have your results interpreted in the correct clinical context to avoid misunderstanding or unnecessary concern.

Complete Blood Count (CBC)

A Complete Blood Count (CBC) is one of the most common blood tests used to assess your general health. It measures different blood cells and can help detect infections, anaemia, inflammation, and underlying health conditions.

White Blood Cells or Leukocytes: Part of the immune system that protects your body from infection. Raised WBCs may be an indication of infection, inflammation, stress, or other immune responses, whereas low levels may be linked to certain medical conditions, such as leukaemia, infection, HIV, or arthritis.

Red Blood Cells: Carry oxygen from the lungs to the tissues throughout the body. Low RBCs may indicate anaemia or nutritional deficiencies. High levels may occur due to dehydration, smoking, and lung or heart-related diseases.

Platelets: Small cells that help the blood to clot and stop bleeding. Low platelet count may lead to slow wound healing that may sometimes cause serious complications due to heavier bleeding. On the other hand, high platelet count can be due to iron deficiency, infections, or, in some cases, more serious underlying conditions.

	Reference Range (Adults)	Above the Reference Range	Below the Reference Range
Red Blood Cells	Men: 4.7–6.1 ×10¹²/L Women: 4.2–5.4 ×10¹²/L	Dehydration, Chronic lung disease, Polycythaemia	Anaemia, bone marrow disease
Mean Corpuscular Volume (MCV)	80–100 fL	Folate or Vitamin B12 deficiency	Iron deficiency, Microcytic anaemia
Mean Corpuscular Haemoglobin (MCH)	27–32 pg	Macrocytic anaemia	Microcytic anaemia, Iron deficiency
Haematocrit (HCT)	Men: 0.40–0.54 Women: 0.36–0.47	Dehydration, Polycythaemia	Anaemia, Excessive bleeding
White Blood Cells	4.0–11.0 ×10⁹/L	Infection, Inflammation, Leukaemia	Bone marrow disorder, Infection, Autoimmune disease
Neutrophils	2.0–7.5 ×10⁹/L	Bacterial infection, Inflammation	Viral Infection, Bone marrow disease, Chemotherapy
Monocytes	0.2-0.8 ×10⁹/L	Leukaemia, Infection, Inflammation	Bone marrow suppression
Lymphocytes	1.0–4.0 ×10⁹/L	Viral Infection, Autoimmune disease, Leukaemia	Chemotherapy, HIV, and Immunodeficiency
Eosinophils	0.0–0.5 ×10⁹/L	Asthma, Allergy, Parasitic Infections	Not usually significant
Basophils	0.0–0.1 ×10⁹/L	Allergy, some forms of blood cancers	Not usually significant
Platelets	150–400 ×10⁹/L	Inflammation, Infection, Iron deficiency, Bone marrow disorder	Bleeding, Autoimmune disorder, Chemotherapy

HbA1c

HbA1c is an essential blood test to determine your average blood sugar level over time to detect diabetes or a prediabetic condition.

Reference Range (Adults)

HbA1c

Normal <42 mmol/mol (≈ < 6.0%)

Increased risk 42–47 mmol/mol (≈ 6.0–6.4%)

Diabetes ≥ 48 mmol/mol (≈ ≥ 6.5%)

Lipid Profile (Cholesterol Panel)

A comprehensive blood screening to test triglycerides and cholesterol levels in the blood. It provides detailed insights about HDL (High-density Lipoprotein), LDL (Low-density Lipoprotein), the total cholesterol to HDL ratio, and levels of triglycerides.

	Reference Range (Adults)	Above the Reference Range	Below the Reference Range
Total Cholesterol	Desirable < 5.0 mmol/L	Increased risk of cardiovascular complications, saturated fats rich diet, Familial hypercholesterolaemia	Malnutrition, Chronic Illness
LDL Cholesterol	Normal Range < 3.0 mmol/L High risk < 2.0–2.6 mmol/L	Diet high in saturated and trans fats, Familial hypercholesterolaemia	Hyperthyroidism, Lipid-lowering treatment
HDL Cholesterol	Men ≥ 1.0 mmol/L Women ≥ 1.2 mmol/L	Endurance exercise, Rare genetic disorder, Certain medicines	Sedentary lifestyle, Smoking, High level of triglycerides, Insulin resistance
Non-HDL Cholesterol	Target < 4.0 mmol/L	Raised level of antherogenic lipoproteins	Reduced level of anthergenic burden
Triglycerides	Normal < 1.7 mmol/L Borderline 1.7–2.2 High > 2.3	Metabolic syndrome, Obesity, Excessive alcohol intake, hypothyroidism	Malnutrition, Hyperthyroidism

Liver Function Test (LFTs)

Liver Function Test determines the levels of ALT, AST, ALP, and bilirubin, essential markers to detect inflammation and liver damage.

	Reference Range (Adults)	Above the Reference Range	Below the Reference Range
ALT	≈ 7–56 U/L	Fatty liver, Drug-induced liver injury, Viral hepatitis	Not usually significant
AST	≈ 10–40 U/L	Alcohol-related liver damage, Muscle injury, Hepatocellular injury	Not usually significant
ALP	≈ 30–130 U/L	Bile duct obstruction, Bone disorders, Pregnancy, Primary biliary cholangitis	Malnutrition, Hypothyroidism, Zinc deficiency, Genetic diseases
GGT	Men ≈ 10–71 U/L Women ≈ 6–42 U/L	Alcohol-induced damage, Biliary disease, Cholestasis	Not usually significant
Bilirubin Total	≈ 3–21 µmol/L	Prehepatic haemolysis, Hepatocellular injury, Cholestasis	Not usually significant
Bilirubin Conjugated	≈ 0–7 µmol/L	Cholestasis, Hepatocellular dysfunction
Albumin	≈ 35–50 g/L	Dehydration	Chronic Liver Disease, Malnutrition, Inflammation
Total Protein	≈ 60–80 g/L	Chronic inflammation, Dehydration	Malnutrition, Liver disease
Albumin to Globulin Ratio	≈ 1.0–2.2	Dehydration	Inflammation, Advanced liver disease

Kidney Function Test (RFTs)

Kidney Function Test helps doctors determine kidney health by assessing key markers, including urea, creatinine, eGFR, BUN, and electrolytes in the blood.

	Reference Range (Adults)	Above the Reference Range	Below the Reference Range
Creatinine	Men ≈ 60–110 µmol/L Women ≈ 45–90 µmol/L	Impaired kidney function, Dehydration, Muscle Injury	Low muscle mass, Pregnancy
Urea	≈ 2.5–7.8 mmol/L	Dehydration, Reduced kidney function, High protein diet	Liver Disease, malnutrition
eGFR	Normal: ≥ 90 mL/min/1.73m² Mildly Reduced: 60–89 Mild CKD: 30–59 SevereCKD: < 30	NA	Acute kidney damage, Chronic kidney disease
Potassium	≈ 3.5–5.0 mmol/L	Kidney failure medication, Tissue damage	Diuretics, Vomiting, Diarrhoea, Cushing’s syndrome
Sodium	≈ 135–145 mmol/L	Dehydration, Excessive salt intake, Endocrine disorder	Adrenal insufficiency, Overhydration, Heart failure
Chloride	≈ 95–105 mmol/L	Dehydration, Kidney disease	Vomiting, Metabolic alkalosis

Thyroid Function Test (TFT)

The thyroid profile provides a complete overview of the levels of T3, T4, and TSH in the blood to detect hypothyroidism and hyperthyroidism.

	Reference Range (Adults)	Above the Reference Range	Below the Reference Range
Free T3	≈ 3.5–6.5 pmol/L	Hyperthyroidism, T3-toxicosis	Hypothyroidism, Non-thyroidal illness
Free T4	≈ 9–25 pmol/L	Hyperthyroidism	Hypothyroidism, Non-thyroidal illness
TSH	≈ 0.4–4.0 mU/L	Primary hypothyroidism, recovery phase of thyroiditis	Primary hyperthyroidism, Hypothyroidism if T4 is also low
Thyroid Stimulating Immunoglobulins	Negative (Assay dependent)	Graves’ disease activity, risk of neonatal thyrotoxicosis in pregnancy

Iron Studies and Ferritin Levels

An iron profile assesses iron levels in the blood as well as those stored in the body.

Difference Between Ferritin and Iron

	Reference Range (Adults)	Above the Reference Range	Below the Reference Range
Ferritin	Men ≈ 30–400 µg/L Women ≈ 15–200 µg/L	Chronic inflammation/infection, Liver disease, Malignancy	Iron deficiency, depletion of stored iron
Serum Iron	≈ 10–30 µmol/L	Haemolysis, Iron overload, Liver disease	Iron deficiency, Severe infection or inflammation
Transferrin	≈ 2.0–3.6 g/L	Iron deficiency, Pregnancy, Oestrogen therapy	Chronic inflammation, Liver disease
Soluble Transferrin Receptor	Assay dependent, often ≈ 1.9–4.4 mg/L	Cellular iron deficiency, Inflammation
Total Iron Binding Capacity	≈ 45–72 µmol/L	Iron deficiency, Pregnancy	Chronic disease or inflammation, malnutrition, Liver disease

Understanding Blood Test Results: What Does the Doctor’s Comment Mean?

Seeing a result outside the reference range on your blood test report can feel worrying, but it does not always mean there is a serious problem. In many cases, changes may be temporary and linked to factors such as diet, hydration, lifestyle habits, medication, or short-term health conditions. Sometimes, these results can return to normal by following your healthcare professional’s guidelines.

Below, we explain some commonly used terms you may see on lab reports with their possible meaning. However, blood test results should always be reviewed by a qualified doctor or healthcare professional to avoid misunderstanding or misinterpretation.

Normal Results

A normal result, often called the reference range, is the expected healthy range for a specific blood marker. These ranges can vary slightly between laboratories depending on the equipment, testing methods, and standardised methods used. Moreover, reference ranges do not apply equally to everyone. Factors such as age, sex, ethnicity, medical history, and overall health can all influence what may be considered normal for an individual.

Abnormal Results

If your blood test report shows values outside the reference range, it may indicate a change that needs specialist advice. However, a slight variation is not always serious and can sometimes be temporary due to factors such as illness, stress, medication, or lifestyle changes. Whether the change is minor or significant, discussing your results with your GP is important to ensure accurate interpretation.

Satisfactory

Your doctor has reviewed the results and found them satisfactory, even if some values are outside the normal range. This may be due to temporary changes such as diet, lifestyle, medication, or an existing health condition.

Borderline

Your test results are close to the upper or lower limits of the normal range and may need repeat testing or a detailed checkup to rule out any underlying concerns.

Borderline Mean in Blood Test Result

Inadequate Specimen

Your sample may not have been suitable for accurate testing, so a repeat sample may be needed to perform the test.

Also Read: Reasons to Repeat a Blood Test

Bottom Line

Understanding your blood test results can feel overwhelming, but self-diagnosis can lead to unnecessary stress and incorrect conclusions. The best approach is to have your results reviewed by a qualified healthcare professional for accurate guidance. If you are looking for trusted private testing with clear results, book a blood test with The National Blood Test Clinic and take the next step towards better health with confidence.

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