Understanding Your Blood Test Results: A Plain Language Guide

Before You Read Your Report

Every laboratory report shows your result next to a reference range, the values found in most healthy people. Results outside the range are usually marked H (high) or L (low).

A flagged result is not automatically a problem. About 1 in 20 healthy people will fall slightly outside the range on any single test, and ranges differ between laboratories, ages and sexes. The ranges below are general guides. Always compare your result with the range printed on your own report, and discuss it with your doctor, who can read it alongside your symptoms and history.

Full Blood Count (FBC or NFS)

This is the most commonly requested blood test. It looks at the three main types of cells in your blood.

• Haemoglobin (Hb): carries oxygen around the body. Roughly 12 to 15.5 g/dL in women and 13.5 to 17.5 g/dL in men. A low result means anaemia, often caused by iron deficiency, heavy periods, pregnancy, malaria or worms.
• White blood cells (WBC): fight infection. Usually about 4,000 to 11,000 per microlitre. A high count often points to an infection or inflammation. A low count can follow some viral infections or medicines.
• Platelets: help your blood clot. Usually about 150,000 to 400,000 per microlitre. Low platelets can occur with malaria, dengue and some other infections.

Blood Sugar

• Fasting blood glucose: below 5.6 mmol/L (100 mg/dL) is normal. 5.6 to 6.9 mmol/L suggests prediabetes. 7.0 mmol/L (126 mg/dL) or above on two occasions suggests diabetes.
• HbA1c: shows your average blood sugar over the past three months. Below 5.7% is normal, 5.7% to 6.4% suggests prediabetes, and 6.5% or above suggests diabetes.

Cholesterol (Lipid Profile)

• Total cholesterol: ideally below 5.2 mmol/L.
• LDL, the 'bad' cholesterol: lower is better. Your doctor will set a target based on your overall heart risk.
• HDL, the 'good' cholesterol: higher is better, ideally above 1.0 mmol/L in men and 1.2 mmol/L in women.
• Triglycerides: ideally below 1.7 mmol/L when fasting.

Kidney and Liver Tests

• Creatinine and eGFR: show how well your kidneys filter blood. An eGFR above 90 is normal. A result below 60 that persists for three months or more suggests chronic kidney disease, often linked to high blood pressure or diabetes.
• ALT and AST: liver enzymes that rise when liver cells are irritated or damaged, for example by alcohol, fatty liver, hepatitis B or C, or some medicines.
• Bilirubin: a yellow pigment processed by the liver. High levels cause yellow eyes and skin.

Other Common Tests

• TSH: checks your thyroid. A high result suggests an underactive thyroid and a low result suggests an overactive one.
• CRP and ESR: general markers of inflammation or infection. They tell your doctor something is going on, but not what.
• Uric acid: high levels can cause gout and kidney stones.
• Hepatitis B (HBsAg) and hepatitis C: a positive result needs follow up with a doctor, even if you feel perfectly well.

A Word About the Widal Test for Typhoid

Many people in East Africa are told they have typhoid based on a Widal test. This test is unreliable. It is often positive in people who had typhoid in the past, were vaccinated, or have other infections, which leads to many unnecessary courses of antibiotics. If typhoid is suspected, ask your doctor whether a blood or stool culture is possible.

How to Prepare for a Blood Test

• For fasting glucose and cholesterol tests, do not eat for 8 to 12 hours beforehand. Plain water is fine.
• Keep taking your usual medicines unless your doctor tells you otherwise, and tell the laboratory what you take.
• Avoid heavy exercise and alcohol the day before.
• Keep copies of your results so you and your doctor can see changes over time.

Laboratory Services at ClinicRW

Our laboratory runs all of the tests above, and our doctors take the time to explain what your results mean for you. An annual checkup with a blood count, blood sugar, cholesterol and kidney function is one of the simplest ways to catch silent conditions like diabetes and high blood pressure early.