You get your report as a PDF, often seven pages or more, with fifty or sixty numbers on it. Some are in bold, some have an H or an L next to them, and the ranges don't look like the ones on the report you got last year from a different lab. This guide explains how to read it, line by line, so you can walk into your doctor's appointment knowing what to ask.
It explains how lab reports are laid out and what the numbers mean. It doesn't tell you what your results mean for your health. That's your doctor's job, because it depends on your symptoms, history and medicines.
The four columns on every report
Whichever lab you use (Dr Lal PathLabs, SRL, Thyrocare, Metropolis, a hospital lab), each result sits on one line with the same four parts:
- Test name: what was measured, such as Haemoglobin or Creatinine.
- Result: your number, or a word like Negative for some urine tests.
- Unit: what the number is counted in, such as g/dL or mg/dL. Two numbers in different units can't be compared.
- Reference range: sometimes printed as Bio. Ref. Interval or Normal range. This is the yardstick your result is compared against.
Two smaller things are worth knowing:
- A line in brackets under the test name, such as (Modified Jaffe, Kinetic) under creatinine, is the method the lab used to measure it. You can usually ignore it, but it's one reason the same test can give slightly different numbers at different labs.
- "Calculated" under a test means the lab didn't measure it directly. It worked it out from other results on the same report. LDL cholesterol and VLDL cholesterol are often calculated from total cholesterol, HDL and triglycerides.
Many labs mark results outside the range with H (high) or L (low), print them in bold, or both.
What the reference range really means
The reference range is not the range of "healthy" values. It's the range that the middle 95% of a group of healthy people fall into. Labs usually set it by testing a large group of healthy volunteers and taking the average plus or minus two standard deviations (Lab Tests Online UK; Houston Methodist lab FAQ).
That has a surprising consequence: about 1 in 20 healthy people will fall outside the range on any single test, just by chance. A full-body checkup runs dozens of tests, so it's common to see one or two flagged values in a report from someone who is perfectly well.
The reverse is also true. MedlinePlus, the US National Library of Medicine's health site, points out that a result inside the range doesn't guarantee you're healthy, and a result outside it doesn't always mean something is wrong (MedlinePlus). Your doctor reads the number together with everything else they know about you.
Some tests don't use a population range at all. Cholesterol and HbA1c are usually printed with target or decision limits instead, such as total cholesterol below 200 mg/dL. Those are set by medical guidelines rather than by measuring healthy people, which is why they look like a single cut-off rather than a band.
Why the same test has different ranges at different labs
If you compare two reports from two labs, you'll often see different reference ranges for the same test. That's expected. Labs use different equipment, chemical methods and reference groups, so each lab sets its own range. The rule of thumb from MedlinePlus is simple: judge each result against the range printed on the same report, not against a number from the internet or a different lab.
When you track a value over time, it's easiest if you use the same lab. If you switch labs, compare where the value sits within each lab's own range rather than the raw numbers.
"Slightly out of range" is different from far out of range
A result just past the limit is a very different thing from one far past it. Research on how people read lab results found that patients often treat a value that's only slightly outside the range as just as worrying as one that's far outside, while doctors usually aren't concerned until a value is further out (Zikmund-Fisher et al., JAMIA).
So when a value is flagged, look at how far it is from the limit. A platelet count of 1.45 lakh/cumm against a lower limit of 1.5 lakh is not the same as 0.5 lakh. Things like dehydration, a recent cold, a hard workout, a heavy meal before a "fasting" test, or some medicines can nudge a value just past the line. That's exactly the kind of thing to raise with your doctor rather than worry about alone.
Units on Indian reports, decoded
Indian labs mix older and newer units, which makes reports from different labs look more different than they are. These are equivalent:
| You might see | It means the same as | Typically used for |
|---|---|---|
| thou/mm³, 10³/µL, ×10³/µL | ×10⁹/L | White cells, platelets |
| mill/mm³, 10⁶/µL | ×10¹²/L | Red cells |
| /cumm, /mm³ | /µL | Any cell count |
| lakhs/cumm | 100,000 per µL | Platelets (1.5 lakh/cumm = 150 thou/mm³) |
| g/dL | 10 × g/L | Haemoglobin, proteins |
| µIU/mL | mIU/L | TSH |
One conversion catches people out: blood sugar. Indian reports use mg/dL, but many international websites use mmol/L. To convert glucose from mg/dL to mmol/L, divide by about 18, so 99 mg/dL is about 5.5 mmol/L.
The same test under different names
Labs name tests differently, and the short forms aren't always explained. These pairs are the same thing:
- SGPT and ALT (alanine aminotransferase), a liver enzyme
- SGOT and AST (aspartate aminotransferase), another enzyme found in the liver and other organs
- Haemoglobin, Hb and HGB
- PCV (packed cell volume) and Haematocrit (HCT)
- TLC (total leukocyte count) and WBC count
- GGTP and GGT (gamma-glutamyl transferase)
- A:G ratio and albumin/globulin ratio
- An "S." in front of a name, as in S. Creatinine, just means it was measured in serum
Reading a full-body checkup section by section
Rather than going number by number, read the report one section, or panel, at a time. Each panel answers a different question about a different part of the body:
- Complete blood count (CBC): your red cells and haemoglobin, white cells and their types, and platelets.
- Liver function (LFT): liver enzymes (ALT, AST, ALP, GGT), bilirubin, and blood proteins such as albumin.
- Kidney function (KFT or RFT): creatinine, urea, uric acid, and often an estimated GFR, which is calculated from creatinine, age and sex.
- Lipid profile: total cholesterol, HDL, LDL, VLDL and triglycerides.
- Thyroid profile: TSH, and usually T3 and T4.
- Diabetes: fasting glucose, and HbA1c, which reflects your average blood sugar over roughly the last three months.
- Vitamins and iron: vitamin B12, vitamin D, iron and TIBC.
- Urine routine: colour, pH, specific gravity, and tests for sugar, protein and cells, often reported as words like Negative, Nil or Few.
Questions to take to your doctor
You'll get more out of the appointment if you bring the report and a few specific questions:
- Which of my flagged values matter for me, and which can I ignore?
- Is any value far enough from the range that we should repeat the test or look further?
- Could my medicines, a recent illness, or what I ate before the test have affected anything?
- How do these numbers compare with my last report?
- When should I test again, and should I fast next time?
Make your report easier to read
FamFirst reads lab reports from Indian labs, whether a PDF, a scan or a phone photo, and lists every result with its reference range, a clear in-range or out-of-range badge, and how far a flagged value is from its limit. Click any result to see the exact line on the original page it came from. You can try it on a sample report without signing up, or check your own report. Your file is deleted as soon as it's read.
Frequently asked questions
Is a result slightly outside the reference range always a problem?
No. Reference ranges cover the middle 95% of healthy people, so about 1 in 20 healthy people fall outside the range on any single test. How far outside the value is, and the rest of your health picture, matter more. Ask your doctor about any flagged result.
What do H and L next to a result mean?
H means the result is above the reference range printed on the report, and L means it's below. Some labs show the same thing in bold, with an asterisk, or with arrows instead.
Why does it say "Calculated" under some tests?
The lab worked that value out from other results on the same report instead of measuring it directly. LDL and VLDL cholesterol and the A:G ratio are common examples.
Can I compare reports from two different labs?
Carefully. Labs use different methods and set their own reference ranges, so compare each result with the range printed on its own report, and check the units match before comparing numbers.
Is SGPT the same as ALT?
Yes. SGPT is the older name for alanine aminotransferase (ALT), a liver enzyme. Likewise, SGOT is the older name for aspartate aminotransferase (AST).
Sources
- MedlinePlus, US National Library of Medicine: How to understand your lab results
- Lab Tests Online UK: Reference ranges and what they mean
- Houston Methodist laboratory services: Lab results FAQ
- Zikmund-Fisher et al., JAMIA: Graphics help patients distinguish between urgent and non-urgent deviations in laboratory test results
This article explains how lab reports are laid out. It isn't medical advice. Talk to your doctor about your results.