Understanding Your Blood Test Results | UK Patient Guide
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 |
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 |
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 |
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 |
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
|
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.
