The anatomy of a blood report
A typical lab report has these columns:
| Column | What it means |
|---|---|
| Test Name | The name of what was measured (e.g., Haemoglobin, TSH, Creatinine) |
| Result / Value | Your actual measured value |
| Unit | The measurement unit (g/dL, mg/dL, IU/L, pg/mL, mIU/L, etc.) |
| Reference Range | The normal range for that test (varies by lab, age and gender) |
| H / L / * flag | H = your result is Higher than normal. L = Lower than normal. * = abnormal |
What do the units mean?
| Unit | Stands for | Commonly used for |
|---|---|---|
| g/dL | Grams per decilitre | Haemoglobin |
| mg/dL | Milligrams per decilitre | Blood sugar, cholesterol, creatinine, uric acid |
| µg/dL | Micrograms per decilitre | Serum iron, TIBC |
| ng/mL | Nanograms per millilitre | Ferritin, PSA, Vitamin D |
| pg/mL | Picograms per millilitre | Vitamin B12, T3, T4 |
| mIU/L or µIU/mL | Milli/micro International Units per litre/mL | TSH, FSH, LH, insulin |
| IU/L or U/L | International Units per litre | Liver enzymes (SGPT, SGOT, ALP) |
| /µL or cells/mm³ | Per microlitre | WBC, RBC, platelet counts |
| % | Percentage | HbA1c, haematocrit, transferrin saturation |
| mm/hr | Millimetres per hour | ESR |
What does it mean when a value is flagged H or L?
H (High) flag
Your result is above the upper limit of the reference range. This does not automatically mean something is seriously wrong. How much above normal, your symptoms, and what other tests show all matter. A mildly elevated value may be insignificant; a very high value may need urgent attention. Context is everything.
L (Low) flag
Your result is below the lower limit of the reference range. Again, mildly low values are often not clinically significant on their own. Low haemoglobin with symptoms = anaemia; borderline low B12 with no symptoms may just need dietary improvement.
Reference ranges — why they vary
Reference ranges differ between labs because they are calculated from the lab's own population of healthy volunteers. This is why a result marked normal in one lab may be flagged abnormal in another. Always compare your result to the reference range printed on YOUR report, not ranges from the internet. Age, gender and pregnancy also shift normal ranges.
How to use this report with your doctor
- Note every value flagged H or L
- Note by how much it's outside the range (slightly vs very)
- Write down your symptoms and when they started
- Ask: "Is this level clinically significant given my symptoms?"
- Ask: "Do I need a follow-up test or can we watch and recheck?"
- Don't self-diagnose — patterns across multiple tests matter more than single values
Explore specific tests
Click any test below to understand its normal ranges and what high or low values mean:
- CBC (Complete Blood Count)
- HbA1c (3-month blood sugar average)
- LFT (Liver Function Test)
- KFT (Kidney Function Test)
- Thyroid Profile (TSH, T3, T4)
- Lipid Profile (Cholesterol)
- Vitamin D
- Vitamin B12
- Urine Routine (R/M)