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Enter your blood test numbers to find out what they mean for your energy — not just whether you're "normal" by lab standards, but whether you're in the optimal range for feeling well.
Enter only the markers you have results for — you can leave the rest blank. Lab ranges vary by provider; this tool uses UK NHS ranges as a baseline and highlights values that are in range but below optimal for energy.
Blood work only tells part of the story
Our AI quiz looks at sleep, stress, diet, lifestyle, and symptoms alongside any blood markers — to give you a complete picture.
Take the fatigue quiz →Blood test reference ranges are built to detect disease — not to ensure you feel well. The "normal" range typically captures the middle 95% of a healthy population, which means someone can be at the very bottom of the range and still be flagged as fine, even while experiencing significant fatigue symptoms.
A ferritin of 15 µg/L is technically normal in most UK labs. But research consistently shows fatigue and brain fog often persist until ferritin is above 50–70 µg/L. This interpreter shows you where your results sit against functional ranges — the levels associated with actually feeling well, not just avoiding disease.
Ferritin (stored iron), vitamin D, TSH and free T3/T4 (thyroid), active B12 (holotranscobalamin), and HbA1c (average blood sugar) are the most commonly missed. Serum magnesium is rarely tested but almost never reflects true magnesium status — only 1% of the body's magnesium is in the blood.
Yes — they can be a useful starting point for a conversation. The functional ranges used here are drawn from published research and represent values associated with symptom resolution in studies. They are not a diagnosis. Your GP has your full clinical picture and should make any treatment decisions.
Yes. Services like Medichecks and Thriva allow you to order specific tests without a GP referral. A panel covering ferritin, vitamin D, active B12, free T3/T4, and HbA1c typically costs £80–£150 depending on the provider. Results are usually returned within 24–48 hours.