When you receive blood test results, you will typically see a list of markers with your value, a reference range, and a flag indicating whether the result is normal, low, or high. Understanding what each marker measures — and what an abnormal result actually means for your health — helps you have a more informed conversation with your doctor.
Common Blood Test Markers Explained
| Marker | What It Measures | Normal Range | If Abnormal |
|---|---|---|---|
| Haemoglobin (Hb) | Oxygen-carrying capacity of blood | Men: 130–170 g/L; Women: 120–150 g/L | Low = anaemia; investigate cause |
| Ferritin | Iron stores | 30–300 µg/L (varies by lab) | Low = iron deficiency; high = inflammation/overload |
| TSH | Thyroid function | 0.4–4.0 mU/L | High = hypothyroid; low = hyperthyroid |
| Total cholesterol | Cardiovascular risk marker | <5.0 mmol/L (ideal) | High = increased CVD risk; assess full lipid panel |
| LDL cholesterol | "Bad" cholesterol | <3.0 mmol/L (or lower if high risk) | High = primary driver of atherosclerosis |
| HbA1c | Average blood sugar (3 months) | <42 mmol/mol (normal) | 42–47 = pre-diabetes; ≥48 = diabetes |
| eGFR | Kidney function | >90 mL/min/1.73m² | <60 sustained = chronic kidney disease |
| ALT | Liver enzyme | Men: <41 U/L; Women: <33 U/L | High = liver inflammation (fatty liver, alcohol, medication) |
| Vitamin B12 | Nerve and blood cell health | >200 ng/L | Low = deficiency; neurological risk if untreated |
| Vitamin D | Bone and immune health | >50 nmol/L (adequate) | Low = deficiency; supplement and retest |
Important note about reference ranges
Reference ranges vary between laboratories. A result flagged as "borderline" in one lab may be "normal" in another. Always interpret results in clinical context — a single abnormal value does not necessarily indicate disease.
What to Do with Your Results
At Victoria Medical, I review every result personally and contact you within 24–48 hours to explain findings. If everything is normal, I confirm this with a brief summary. If any result requires action — whether that is a repeat test, lifestyle modification, treatment, or referral — I explain exactly what is needed and why. You are never left to interpret results alone. Learn about our blood test service →
From Our Practice
"The most common question I receive is 'my result says normal but I still feel unwell.' This is where clinical context matters. A TSH of 3.8 is technically within range, but if you have fatigue, weight gain, and a family history of thyroid disease, it may warrant a trial of treatment. Numbers alone do not tell the full story."
— Dr George Xynopoulos, Consultant Physician
Frequently Asked Questions
How long do blood test results take?
At Victoria Medical, most results are available within 24 hours. Some specialist tests (e.g., hormonal panels, tumour markers) may take 48–72 hours.
What does 'borderline' mean?
A borderline result sits at the edge of the reference range. It may require monitoring (repeat test in 3–6 months) or clinical assessment depending on your symptoms and risk factors.
Should I be worried about a single abnormal result?
Not necessarily. Many factors can temporarily affect blood results — dehydration, recent illness, medications, time of day. I always interpret results in the context of your overall clinical picture.
Can I get my results explained privately?
Yes. If you have had blood tests elsewhere (NHS or another provider) and want them reviewed, I offer results-interpretation consultations where we go through every marker together.
How often should I have blood tests?
For general health monitoring, I recommend annual blood work from age 30–35. More frequent testing may be needed if you have chronic conditions, take medications, or have specific risk factors.
Do I need to fast before blood tests?
A 10–12 hour overnight fast is required for accurate lipid and glucose measurements. Water is fine. Other tests (FBC, thyroid, B12) do not require fasting.
Related Guides
Blood Tests at 40
Essential panels by age
Cholesterol Explained
What your numbers mean
Thyroid Function Test
TSH, T4, and T3 explained
Private Blood Tests
Same-day results
References
- [1] Langan RC, Goodbred AJ. Vitamin B12 deficiency: recognition and management. Am Fam Physician. 2017;96(6):384–389. View source
- [2] NICE CKS. Lipid modification — CVD prevention. 2023. View source
- [3] Diabetes UK. HbA1c and diagnosis. 2024. View source
- [4] NICE CKS. Anaemia — iron deficiency. 2024. View source
- [5] Chaker L, et al. Hypothyroidism. Lancet. 2017;390(10101):1550–1562. View source
- [6] Kidney Disease: Improving Global Outcomes (KDIGO). CKD evaluation and management. Kidney Int. 2024;105(4S):S117–S314. View source
