Blood Test Preparation

Blood Test Preparation

Blood tests are crucial indicators of body function. Often, changes in certain metrics occur before any symptoms manifest. Detecting these deviations in time allows for early intervention, easing the treatment process. For patients already undergoing treatment, monitoring various indicators helps assess treatment effectiveness.

The final blood test result largely depends on the patient’s preparation quality. Modern technology allows for precise data acquisition in the shortest time possible, but several constraints must be respected to ensure device functionality. How can adults properly prepare for venous blood analysis, and what rules should be followed? Here are some general recommendations and specific steps.

General Recommendations for Preparation:

It’s important to understand that most metrics change based on food intake, physical activity, and time of day. Therefore, the main rules for preparing for venous blood analysis do not depend on the type of study.

  1. Avoid fatty foods and alcohol 1-2 days before the test.
  2. It’s best to have the blood test done in the first half of the day on an empty stomach.
  3. Reduce physical activity and avoid exposure to extreme cold or heat.
  4. Avoid physical and emotional stress and smoking one hour before the test.
  5. On the day of the test, drink plenty of water 2-3 hours before, and refrain from tea, coffee, and juices.
  6. Coordinate medication intake with the treating physician on the day of the test.
  7. Avoid giving blood immediately after physical therapy sessions and other medical procedures.

These general rules apply to all tests, but some tests may require special preparation and additional restrictions. It’s important to strictly follow specific guidelines to ensure accurate test results.

General Clinical Blood Analysis:

  • In emergencies, clinical blood analysis can be done without preparation. For planned examinations, adherence to general preparation rules is required.

Chemical Blood Analysis:

  • This analysis allows the assessment of metabolic parameters, minerals, and calculates certain ratios and risks. Patient preparation before giving blood for this analysis involves dietary restrictions and fasting for 8-12 hours, with water consumption allowed.

Urea and Uric Acid:

  • It’s preferable to avoid liver and kidney consumption, and reduce the intake of meat, fish, coffee, and tea in the diet 2-3 days before the analysis.

Cholesterol, Triglycerides, High-Density Lipoproteins, Low-Density Lipoproteins:

  • Blood should be given fasting for 12-14 hours, and fatty foods should be avoided 1-2 days before the analysis.


  • Blood should be given fasting for 12-14 hours, with only water allowed to drink.

Glucose Tolerance Test:

  • Done under the doctor’s instructions, this test requires special preparation 3 days before the procedure.

Vitamin D:

  • Before analyzing vitamin D levels, refrain from taking any supplements or medications containing cholecalciferol and hydroxycholecalciferol for 3 days.

Infection Blood Test:

  • For accurate results, it’s preferable to follow general blood preparation rules for clinical analysis, reduce physical activity, avoid smoking and alcohol, sauna visits, and urinating for at least 8 hours.

Blood Hormones:

  • It’s advisable to repeat blood hormone tests for accurate results and dynamic comparison. The analysis should be done at the same time of day after 2-3 weeks. Medication intake should be minimized and coordinated with the doctor.

Thyroid Function:

  • Morning is the optimal time for giving blood. The test should be done at the same time and in the same lab, with medication intake minimized (or stopped altogether, coordinated with the doctor). TSH analysis should be avoided during acute inflammation and against the background of lipid and/or vitamin metabolism disorders.

Sex Hormones:

  • Blood hormones of the reproductive system should be given according to specific days of the menstrual cycle.

Renin-Aldosterone System and Cortisol Hormone:

  • Renin, aldosterone, and cortisol hormones should be given fasting in the first half of the day, with rest and relaxation 30 minutes before the procedure.

Cancer Marker Tests:

  • Prostate-specific antigen – PSA (total, free)
  • Men should follow standard preparation rules for blood analysis. They should also remember that PSA should not be determined before 2 weeks after prostate massage and after 6 weeks or more after prostate surgery.

H3 CA-125:

  • Blood analysis is preferred 2-3 days after the end of the menstrual period. During menopause, blood analysis is recommended annually.

Fatty, salty, and fried foods should be excluded from the diet 24 hours before blood analysis.

Blood Coagulation System (Coagulogram):

  • This test includes several parameters: fibrinogen, prothrombin (Quick time, International Normalized Ratio), thrombin time, lupus anticoagulant, D-dimer, von Willebrand factor, plasminogen.
    Blood should be given in the first half of the day on an empty stomach. Drinking pure water is allowed. If necessary, blood analysis can be done during the day, but not earlier than 3 hours after eating.