How to Understand Your Blood Test Results
Most blood test reports print three things next to every parameter: your result, the laboratory's reference range, and a flag if the value sits outside that range. This guide explains what the common parameters actually measure, what the normal ranges are, and what a high or low value usually indicates — in plain language, without medical jargon.
Reference ranges vary between laboratories and by age, sex and pregnancy. Use the range printed on your own report, and treat this page as background reading rather than a diagnosis.
On this page
Complete Blood Count (CBC)
The CBC is the most commonly ordered blood test. It measures the cells circulating in your blood and is used to screen for infection, anaemia, and clotting problems.
| Parameter | Typical range | What it usually means |
|---|---|---|
| Haemoglobin (Hb) | 13.0–17.0 g/dL (men), 12.0–15.0 g/dL (women) | Low values suggest anaemia — often iron, B12 or folate deficiency. High values can follow dehydration or smoking. |
| Total WBC count | 4,000–11,000 cells/µL | High counts commonly point to a bacterial infection or inflammation. Low counts can follow a viral illness or certain medications. |
| Platelet count | 150,000–410,000 cells/µL | A falling platelet count is a classic dengue marker. Very low counts increase bleeding risk and need prompt review. |
| Haematocrit (PCV) | 40–50% (men), 36–44% (women) | Rises with dehydration and plasma leakage; falls alongside haemoglobin in anaemia. |
| MCV | 80–100 fL | Small cells (low MCV) suggest iron deficiency; large cells (high MCV) suggest B12 or folate deficiency. |
Dengue, Widal and other infection panels
Infection reports are often reported as reactive/non-reactive or as titres, which makes them harder to read than a simple number.
| Parameter | Typical range | What it usually means |
|---|---|---|
| Dengue NS1 antigen | Non-reactive | Detects dengue in the first 1–5 days of fever. Reactive means active infection. |
| Dengue IgM / IgG | Non-reactive | IgM reactive indicates a recent infection; IgG alone often reflects a past infection. |
| WBC count in dengue | 4,000–11,000 cells/µL | Typically falls, together with platelets, around days 3–7 of illness. |
| Widal test (typhoid) | Titre below 1:80 | Titres of 1:160 or higher for O or H antigens are usually considered significant, but the test needs clinical context and often a paired sample. |
| CRP | Below 5 mg/L | A general inflammation marker — raised in infection, injury and chronic inflammation. |
Sugar, lipids, thyroid
These are the numbers most often tracked over time in preventive and corporate health checks.
| Parameter | Typical range | What it usually means |
|---|---|---|
| Fasting blood glucose | 70–99 mg/dL | 100–125 mg/dL is prediabetes; 126 mg/dL or above on two occasions suggests diabetes. |
| HbA1c | Below 5.7% | Reflects average sugar over about 3 months. 5.7–6.4% is prediabetes; 6.5% and above suggests diabetes. |
| LDL cholesterol | Below 100 mg/dL | The 'bad' cholesterol — the main target in cardiovascular risk reduction. |
| HDL cholesterol | Above 40 mg/dL (men), above 50 mg/dL (women) | Protective cholesterol; higher is generally better. |
| Triglycerides | Below 150 mg/dL | Rises with alcohol, refined carbohydrates and uncontrolled diabetes. Requires proper fasting for accuracy. |
| TSH | 0.4–4.0 mIU/L | High TSH suggests an underactive thyroid; low TSH suggests an overactive thyroid. |
Liver and kidney function
Organ panels are read as a group — one mildly abnormal value in isolation is rarely meaningful.
| Parameter | Typical range | What it usually means |
|---|---|---|
| SGPT / ALT | 7–56 U/L | Raised in fatty liver, alcohol use, viral hepatitis and with some medications. |
| SGOT / AST | 10–40 U/L | Interpreted alongside ALT; the AST:ALT ratio helps distinguish causes. |
| Total bilirubin | 0.3–1.2 mg/dL | High values cause jaundice and can be haemolytic, hepatic or obstructive in origin. |
| Serum creatinine | 0.7–1.3 mg/dL (men), 0.6–1.1 mg/dL (women) | The core kidney marker; rises as filtration falls. |
| eGFR | Above 90 mL/min/1.73m² | Below 60 sustained for three months defines chronic kidney disease. |
| Blood urea | 7–20 mg/dL | Affected by kidney function, protein intake and hydration. |
Frequently asked questions
What does 'reference range' mean on a blood test report?
The reference range is the span of values seen in most healthy people tested on that particular analyser. Ranges differ slightly between laboratories, so always compare your result with the range printed on your own report rather than one from another lab.
Is a result just outside the reference range a problem?
Usually not on its own. Reference ranges are statistical, so roughly 1 in 20 healthy people fall marginally outside them. Trends across repeat tests, and the full clinical picture, matter far more than a single borderline value.
Which blood tests need fasting?
Fasting glucose, lipid profile and insulin usually require 8–12 hours without food, with water allowed. CBC, thyroid and most infection panels do not require fasting.
Why do results differ between two laboratories?
Different analysers, reagents, calibration and units produce small variations. For monitoring a condition over time, it is best to stay with one laboratory.
Can I get a blood test done at home?
Yes. A trained phlebotomist can collect samples at home for almost all routine tests, provided the sample is kept in the correct temperature range and reaches the laboratory within the stability window. Phlebify runs this collection layer for diagnostic labs, hospitals and clinics across India.