Blood tests from A to Z: what each value measures

Every item in the Rosa panel, explained in one line: what it measures and how often we test it. Some items, like the urinalysis, hold several values: in total, your report shows more than 80.

Heart and circulation

• Total cholesterol: The sum of the different kinds of cholesterol. On its own it says little.
• LDL cholesterol: Carries cholesterol to your tissues. If it stays high for years, it builds up in the arteries.
• HDL cholesterol: Takes extra cholesterol out of the arteries and back to the liver.
• Triglycerides: The fats your body burns as fuel. More than any other value, they react to what you ate and drank.
• ApoB (apolipoprotein B): Counts the particles that can build up in your arteries.
• Lipoprotein(a): A particle that can build up in your arteries. Its level is set almost entirely by your genes.
• High-sensitivity CRP: Background inflammation, the kind you do not feel.

Metabolism

• Fasting glucose: Your blood sugar after a night without food.
• HbA1c: Your average blood sugar over the last two to three months.
• Fasting insulin: How hard your pancreas works to keep your blood sugar normal.
• Uric acid: A waste product your body makes when it recycles old cells and digests some foods. It shows how your metabolism is doing.

Thyroid

• TSH: The hormone your pituitary gland, at the base of the brain, uses to tell your thyroid to work harder or less.

Liver

• ALT: An enzyme inside liver cells. It rises when the liver is under strain.
• AST: An enzyme found in the liver, but also in muscle and the heart.
• GGT (gamma GT): A liver enzyme that reacts strongly to alcohol.
• Alkaline phosphatase (ALP): An enzyme that comes from the liver and from bone.
• Bilirubin (total, direct, indirect): A waste product of recycling red blood cells. When it is only slightly high, it is often harmless.
• Albumin: The most common protein in your blood. It reflects your liver, nutrition and inflammation.

Kidneys and minerals

• Magnesium: The magnesium in your blood, only a small part of your body’s total.
• Creatinine: A muscle waste product your kidneys clear.
• eGFR: An estimate of how well your kidneys filter, calculated from creatinine.
• Sodium: The balance of water and salt in your body, not how much salt you eat.
• Potassium: Keeps your heartbeat steady and your muscles working.
• Calcium: The calcium in your blood, which your body keeps within tight limits.

Iron and vitamins

• Vitamin D (25 OH): Your body’s store of vitamin D.
• Vitamin B12: Your nerves and red blood cells need it. If it runs short, symptoms come late.
• Serum iron: The iron in your blood today, not your store.
• Ferritin: Your body’s iron store.
• Transferrin saturation: How much of your blood’s room to carry iron is already filled.
• TIBC (total iron-binding capacity): How much room your blood has to carry iron. It rises when iron runs short.

Red blood cells and platelets

• Red blood cells: How many cells carry oxygen.
• Haemoglobin: The protein that carries oxygen. It is the number that shows anaemia.
• Haematocrit: How much of your blood is red cells. It shifts a lot with how much water you drink.
• MCV: How big your red cells are. It helps explain the cause of anaemia.
• MCH: How much haemoglobin an average red cell holds.
• MCHC: How concentrated the haemoglobin in your red cells is.
• RDW: How much your red cells differ in size.
• Platelets: Cell fragments that stop bleeding when you get hurt.
• MPV: How big your platelets are. Young platelets are bigger.

White blood cells

• White blood cells: Your immune cells. The total says how busy they are, not what they fight.
• Neutrophils: The first defence against bacteria, and your most common white cells.
• Lymphocytes: The cells that remember infections you have met before.
• Monocytes: They clean up debris in your tissues and alert the rest of your defences.
• Eosinophils: The cells that react to allergies and parasites.
• Basophils: Your rarest white cells. They often read zero, which is normal.

Urine

• Urinalysis: Checks your urine for protein, blood, sugar and signs of infection.
• Urine albumin (uACR): The earliest sign of kidney strain, years before filtration falls.

How to read your blood test results

Six things to know before you worry about a number:

• Next to each value is the lab’s reference interval. It changes from one lab to another.
• Many values appear as an abbreviation, like ALT or CRP: type it in the search box above.
• An asterisk, an arrow or the letters H and L mark a value outside that interval: H means high, L means low.
• Outside the interval does not mean ill. What matters is by how much, and why.
• Values are read together: one on its own says little.
• An odd value is usually checked again before drawing conclusions.

Frequently asked questions

Do I need to fast for a blood test? For many tests, yes: glucose, insulin and triglycerides, for example. You are usually asked not to eat from the evening before. You can drink water.

Which blood tests matter most? It depends on your age and history. For prevention, doctors usually look at the blood count, glucose, cholesterol, liver, kidneys and thyroid. The Rosa panel includes all of them.

What does the asterisk on my report mean? That the value is outside the lab’s reference interval. It is not a diagnosis: it only tells you where to look.

Are biomarkers the same as tumour markers? No. A biomarker is any value that can be measured, in the blood for example. The Rosa panel does not include tumour markers.

How often should I have blood tests? For people who feel well there is no fixed rule: it depends on age, health and past results. Rosa does a full blood test every year and re-checks the core values after six months.