Blood chemistry tests: what they are, which ones and how to read them

In Italy, esami ematochimici, blood chemistry tests, is the name used for blood tests. One draw shows how your blood, blood sugar, blood fats, liver and kidneys are doing. Here are the routine ones, what each one tells you and how to read your report.

• What they are: Tests on a blood sample
• How they are done: With a draw from your arm
• Fasting: For many, yes: 8 to 12 hours
• On your report: Value, unit and the lab’s interval

What blood chemistry tests are

The Italian word joins emato, blood, and chimico, chemical. Strictly speaking, these are the tests that measure what is dissolved in your blood: sugar, fats, enzymes, salts, waste products like creatinine.

The full blood count, which counts your blood cells, would strictly be a haematology test. But in everyday use, among doctors too, blood chemistry tests means the blood tests from one draw, full blood count included.

A blood chemistry draw, prelievo ematochimico, is the blood draw done for these tests.

Which blood chemistry tests are routine

There is no official list: your doctor chooses the tests, based on your age, your health and the reason for the check. These are the most common. Tap a test to learn what it measures.

• Full blood count: Red cells, white cells and platelets. It shows whether you have anaemia and how your defences are doing.
• Glucose: Your blood sugar after a night without food.
• Total cholesterol: The sum of all the cholesterol in your blood. On its own it says little.
• HDL cholesterol: The cholesterol that goes back to the liver, called good cholesterol.
• LDL cholesterol: The cholesterol that builds up in the arteries if it stays high for years.
• Triglycerides: The fats your body burns as fuel. They react a lot to what you ate and drank.
• Liver enzymes (AST and ALT): Two liver enzymes, also printed as GOT and GPT. They rise when your liver is under strain.
• GGT: A liver enzyme that reacts strongly to alcohol.
• Creatinine and eGFR: How well your kidneys filter. eGFR is an estimate calculated from creatinine.
• Urea: The waste product of protein. It changes with what you eat, how much you drink and how your kidneys work.
• Sodium: The balance of water and salt in your body.
• Potassium: The mineral that keeps your heart and muscles working.
• Uric acid: A waste product your kidneys clear. It shows how your metabolism is doing.
• ESR: A general sign of inflammation. It does not say where it is, or why.
• Urinalysis: Not a blood test, but almost always done alongside: protein, blood, sugar and signs of infection.

Urea and ESR are not in the Rosa panel: the other tests on this list are.

Tests that are often added

On top of the basic ones, your doctor often adds a few, depending on who you are and what they are looking for:

• HbA1c: Your average blood sugar over the last two to three months.
• Ferritin: Your iron store. It is usually the first to drop when iron runs short.
• CRP (C-reactive protein): Inflammation in your body. With an infection it rises within hours.
• TSH: The first test for your thyroid.
• Vitamin D: Your store of vitamin D, often low in winter.
• Vitamin B12: Your nerves and red blood cells need it. If it runs short, symptoms come late.

How the draw works

Blood is drawn from a vein in your arm, and it takes a few minutes. It goes into a few tubes, because different tests need different tubes.

Many tests need fasting: nothing to eat for 8 to 12 hours, water is fine. Glucose, insulin and triglycerides change after a meal.

Then the lab prepares your report, usually to download online.

How to read your report

Every line of your report has the same parts. Read them in this order:

• The name of the test: It is often an abbreviation, like GPT, CRP or Hb. The same test can have two names: GPT and ALT are the same thing.
• Your value and its unit: The unit matters: the same test in different units gives very different numbers. Only compare values in the same unit.
• The reference interval: These are the limits printed next to your value. The lab sets them, based on healthy people, and they change from one lab to another. What counts is the one on your report, not one found online.
• The mark next to the value: An asterisk, an arrow, bold type or the letters H and L mark a value outside the interval: H means high, L means low. It is not a diagnosis: it only tells you where to look.
• The values around it: Values are read together. One on its own says little: what matters is whether others in the same group move too, and what they were in your earlier reports.

A value outside the interval: what it means

Usually, less than it seems. The reference interval holds the values of 95 healthy people in 100. That means 5 healthy people in 100 have that value outside, just by chance.

The more tests you have, the more likely it is that at least one falls slightly outside, even if you are well.

Many values also change with what you did before the draw: a meal, alcohol, hard exercise, too little water, a passing illness, some medicines or supplements. The draw itself matters too: potassium, for example, can read high if red cells break in the tube.

For some tests, like cholesterol, the printed limit does not describe healthy people: it is a threshold chosen for prevention.

A value slightly outside, with no symptoms, is usually checked again. What matters is how far outside it is, whether other values move too and whether it stays outside on the re-check.

When to see a doctor

Talk to your doctor if:

• A value is far from your report’s limits, not just slightly.
• Several values in the same group are outside, for example your liver or kidney values.
• A value is still outside at the next check.
• You also have symptoms, like tiredness that will not go away, fever or weight loss for no reason.
• The lab flags a value to be seen at once: see a doctor the same day.
• You have chest pain, sudden breathlessness, fainting or confusion: call 112 or go to the emergency department.

Bring your earlier reports to your doctor too: the change over time often says more than a single value.

Blood chemistry tests and a check-up: the difference

Blood chemistry tests means the tests, whatever they are. A doctor usually orders them to answer a specific question: a symptom, a medicine to monitor, an operation.

A check-up is a set of tests chosen for people who feel well. It looks at all the main areas in one draw: heart, blood sugar, liver, kidneys, blood, iron, vitamins and thyroid.

The Rosa check-up runs 31 tests in the first draw, blood and urine. Six months later, a second draw re-checks the 10 core tests.

Other guides

• Thyroid tests: TSH, FT4, FT3 and antibodies: what each measures and when you need it.
• What blood tests cost: With a GP prescription, at private labs and with Rosa.
• Blood tests and prescriptions: When you need a doctor’s prescription and when you do not.

Frequently asked questions

Are blood chemistry tests and blood tests the same thing? In everyday use, yes. Strictly speaking, blood chemistry tests measure substances in the blood, like glucose and cholesterol, while the full blood count counts cells. But people usually call them all blood chemistry tests.

Do I need to fast for blood chemistry tests? For many, yes: glucose, insulin and triglycerides, for example. Nothing to eat for 8 to 12 hours, water is fine. The lab tells you what your tests need.

Do I need a prescription for blood chemistry tests? Through the national health service, yes: your GP writes it. Private labs usually do not ask for one. With Rosa you do not need one: Rosa prepares the test request.

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

Does a value out of range mean I am ill? No. Many healthy people have one or two values slightly outside, by chance or because of how the draw went. What matters is how far outside it is, whether other values move too and whether it stays outside on the re-check.

What do H and L mean on my report? H stands for high and L for low, compared with the lab’s interval. Some reports use an asterisk or an arrow instead. They mark where to look, not an illness.

Have your blood tests with Rosa

31 tests in the first draw, blood and urine, and a re-check of your core values six months later. Every value explained in plain words and a doctor who approves your report. At a partner lab, no prescription needed. €295 a year.

Sources

• Ozarda, reference intervals: current status, recent developments and future considerations. Biochemia Medica, 2016. PMID 26981015
• Lippi and colleagues, preanalytical variability: the dark side of the moon in laboratory testing. Clinical Chemistry and Laboratory Medicine, 2006. PMID 16599826