Tests and treatments

Blood test

What is it?

What is it?

A blood test can provide substantial information for the diagnosis and treatment of patients. The goal of the test depends on the requested measurements, the measurement interval and your condition.

What is the process?

What is the process?

Preparation

You do not need to be fasting for a blood draw.

For fasting blood glucose tests, you need to be fasting (your physician will inform you if that is the case):

  • No drinks or food after midnight.
  • Medication, however, may be taken with a sip of water.

Test

Blood is usually taken from a vein in the fold of the elbow. In order to see the veins well, a tourniquet will be wrapped around your upper arm. The vein will be pricked and blood will be collected in a small tube.

Certain cardiac patients preventatively take anticoagulation medication, Vitamin K antagonists. Is this the case with you? Notify the nurse for the blood draw.

Possible complications

Possible complications

A blood draw has few associated risks.

Local bruising is possible but does not require much looking after.

Results

Results

Several things can be measured in the blood. A few of these important measurements are discussed below.

BNP stands for Brain Natriuretic Peptide. That's a protein. Muscle cells that are in the heart chamber/ventricles secrete this protein if they have been under increased pressure for a long time.

  • An elevated NTproBNP level in the blood is clinical evidence of heart failure.
  • A low NTproBNP level in the blood rules out heart failure.

Heart muscle cells die when they do not get oxygen during a heart attack. When these dead cells break apart, they release cardiac enzymes.

If these cardiac enzymes are found in the blood, this means that the heart is damaged. Shortly after a heart attack, the level of cardiac enzymes is at its highest. It then decreases over the course of a few days, more or less in a predicable fashion.

Troponin is a sensitive parameter of cardiac muscle degradation. Troponin is also more specific than other parameters, such as CK (creatine kinase), SGOT (transaminase glutamate oxaloacetate), SGPT (transaminase glutamate pyruvate) and LDH (lactate dehydrogenase).

Cholesterol is a fat that the body needs as a building block substance. Cholesterol is usually made in our liver (90%). A small amount of cholesterol is consumed in our diet (10%). Cholesterol circulates in our blood in the form of tiny balls.

Cholesterol is divided into LDL and HDL components.

  • LDL cholesterol transports fats from the liver to the body. the LDL is too high, then there is too much cholesterol in the blood and it can collect on the blood vessel wall. This could lead to constrictions in the arteries. The LDL (bad cholesterol) level should be low. HDL cholesterol removes deposited LDL cholesterol from the vessel wall and transports it to the liver.
  • HDL (good cholesterol) levelsshould be highas they reduce the risk of constrictions.

When cholesterol levels are measured, the target values (for primary prevention) are:

  • LDL
    <115 mg/dl (or <5.0 mmol/l)
  • HDL
    in men: >= 40 mg/dl (>=1.0 mmol/l)
    in women: >=45 mg/dl (>=1.2 mmol/l)

If you have a high risk of cardiac or vascular disease (this is the case for secondary prevention), your physician will set stricter guidelines.

Glucose is a sugar that our body needs as a source of energy. Our body makes glucose from dietary carbohydrates. After eating, the glucose level in the blood increases. Insulin ensures that the blood sugar level does not get too high.

In diabetes, the glucose level in the blood is too high.

There are two possible causes:

  • Type 1 diabetes: the patient cannot produce insulin, causing blood glucose levels to rise uncontrollably. Type 1 diabetes often occurs in young patients and is treated with insulin injections.
  • Type 2 diabetes: this form often occurs later in life (adult-onset diabetes). With this type of diabetes, insulin is still produced, but reacts less effectively in the body. There is often a combined problem of high blood pressure, obesity and high cholesterol.

Diabetes is a very important risk factor for coronary disease.

Blood sugar must be measured while you are fasting.

Glucose target valuesare:
<110 mg/dl or <6.1 mmol/l

In some cases, extra tests must be performed:

  • Oral Glucose Tolerance Test (OGTT): This test is an extensive diagnostic test and is performed when a simple blood test shows that there is a possibility of diabetes. The test consists of multiple blood draws at fixed intervals after having consumed a glucose drink.
  • HbA1c test: Diabetics have changes in the haemoglobin in the blood. These changes are measured with the HbA1c, which is measure of the blood sugar level over a longer period of time.
  • The medication dose must be set according to the speed with which the blood coagulates. This can be measured with a blood draw. The degree of anticoagulation can be measured with some medication (INR measurement).
    • A dose that is too high thins the blood too much. This means that every bruise can trigger serious bleeding or that spontaneous bleeding may occur.
    • A dose that is too low can have an insufficient effect on preventing spontaneous clot formation in the heart, which could lead to stroke.

Centres and specialist areas

Centres and specialist areas

Latest publication date: 16/05/2024
Supervising author: Apr. Biol. Baetens Dimitri, Dr Elzo Kraemer Ximena