The Body Detectives

Your lab results, decoded by a doctor.

Plain-English guides and free tools for your blood tests, vitamins, hormones and the numbers on your smartwatch. Understand what each result means, and what to ask your doctor next.

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Written by Dr. Mustafa Sakr, MBBCh. Educational, never a diagnosis.

Example report4 flags
TSH6.2 mIU/L0.4–4.0H
Ferritin9 ng/mL15–150L
Vitamin D18 ng/mL30–100L
HbA1c5.9 %< 5.7H
Four clues worth a closer look. Tap a test to decode it with our free interpreter.

Sample values for illustration only. Reference ranges differ between labs, so always use the range printed on your own report.

  • 60+ guideswritten by a doctor
  • 4 free toolsto read your results
  • Linked sourcessuch as the NHS and NIH
  • Free to readand supported by ads

Free tools

Free lab result interpreters

Type in the number from your report and see where it sits, what it may suggest, and which questions to bring to your doctor.

TSH Interpreter

Check whether your thyroid result is normal, high or low, and read it alongside Free T4 and Free T3 if you have them.

mIU/L

Vitamin D Interpreter

See whether your 25-OH vitamin D level is low, sufficient or too high, in whichever unit your lab uses.

ng/mL · nmol/L

HbA1c Interpreter

Find out if your HbA1c is in the normal, prediabetes or diabetes range, with your estimated average blood sugar.

% · mmol/mol

Ferritin Interpreter

Read your iron stores as low, normal or high, using ranges adjusted for your sex. Ferritin often falls before anaemia shows.

ng/mL · µg/L
  1. Enter your resultUse the number and unit printed on your lab report.
  2. See where it sitsNormal, borderline or out of range, explained in plain English.
  3. Ask better questionsTake a short list of questions to your next appointment. Your numbers stay in your browser.

Browse by topic

Everything your report might mention

Start with the most-read guide in each topic, or open the full collection.

The casebook

Health puzzles, solved like a detective

A doctor takes one everyday symptom, lines up the suspects and follows the blood-test clues to the cause. Fictional cases, real lessons.

Open the casebook

Who writes this

Written by a doctor, for real people

The Body Detectives is written by Dr. Mustafa Sakr, MBBCh, a medical doctor. Each guide explains what a test measures, what the usual ranges are, what high or low results can mean, and when a result is worth discussing with your own doctor.

The goal is simple: the clear explanation you wish someone had given you the first time you read a lab report.

About the author →Medical disclaimer →

  • Plain EnglishNo jargon and no fear-mongering. Medical terms are explained the first time they appear.
  • Grounded in reputable sourcesGuides link to trusted health organisations such as the NHS and the NIH.
  • Educational, never a diagnosisOnly your own doctor, who knows your history, can interpret your results for you.

Questions

Frequently asked questions

Is The Body Detectives medical advice?

No. Everything on this site is educational. It can help you understand your results and prepare questions, but it cannot diagnose or treat you. Always discuss your results with your own doctor. Read our medical disclaimer.

Are the tools and guides free?

Yes. Every guide and all four interpreter tools are free to use. The site is supported by advertising.

Do you store the results I enter in the tools?

No. The interpreters run in your browser. The values you type in are used only to show your result on screen. They are not sent to us and are not stored. See our privacy policy.

Why is my lab’s reference range different from yours?

Reference ranges vary between laboratories, testing methods and countries. Our guides show typical adult ranges, but the range printed on your own report always comes first.

Who writes the guides?

All guides are written by Dr. Mustafa Sakr, MBBCh, a medical doctor and the founder of The Body Detectives. Learn more about the author.

Get the free “Decode Your Labs” guide

A doctor’s pocket guide to TSH, vitamin D, HbA1c and ferritin, with the ranges that matter and the questions to ask. Sent straight to your inbox, free.

Get the free guide →

The Body Detectives provides educational health information only. It is not a substitute for professional medical advice, diagnosis or treatment.