Blood test — what your results actually mean

Dr. Charalampos Romanos · 28 December 2025 · 7 min read

You've received your blood results and wonder what the numbers mean? Many patients face a lab report feeling uncertain. Here's a guide to the most important values.

Ferritin — iron stores

Ferritin measures how much iron your body has stored. Below 30 µg/L indicates deficiency, even if haemoglobin is still normal. Ideal values are above 50 µg/L. Especially with fatigue and iron deficiency symptoms, ferritin is the key value.

TSH — thyroid

TSH (thyroid-stimulating hormone) shows how active your thyroid is. Normal: 0.27–4.2 mU/L. High TSH suggests underactive thyroid, low TSH suggests overactive. For borderline values, I recommend fT3 and fT4 as well — more in our thyroid article.

HbA1c — long-term blood sugar

HbA1c shows average blood sugar over the past 2–3 months. Below 5.7% is normal, 5.7–6.4% is prediabetes, 6.5% and above indicates diabetes. This value is more reliable than a single fasting glucose.

CRP — inflammation marker

CRP (C-reactive protein) rises with inflammation. Below 5 mg/L is normal. Elevated values can indicate infections, autoimmune conditions, or chronic inflammation. A mildly elevated CRP in isolation must be assessed in context.

Liver values (GPT/ALT, GOT/AST, GGT)

These enzymes indicate liver function. Mildly elevated values can be caused by medication, alcohol, fatty liver, or excess weight. Significantly elevated values require further investigation.

Values always in context

A single value outside the normal range is not automatically a problem. We discuss every result personally and decide together whether and what next steps make sense.