Sample collection is usually performed at a physician’s request, for the following reasons:

• Medical checkup

• Diagnosis of a disease (clarifying a suspected diagnosis)

• Monitoring and follow-up of a confirmed disease

• Evaluating the success of treatment

• Assessing the future course of a disease (prognosis)

Before blood is drawn, several points must be observed to ensure the accuracy and validity of the test results:

• If you have any particular medical condition, such as hemophilia, coagulation disorders, or epilepsy, inform the phlebotomist and, if necessary, the laboratory physician.

• Time of collection: Ideally in the morning, between 7:00 and 9:00 a.m.

• Fasting: For certain tests (for example, blood glucose), the patient must be fasting. Fasting does not mean starving! Do not eat anything from 8:00 p.m. the evening before. On the morning of the blood draw, a small amount of water or unsweetened tea is allowed. Prescribed medications should be taken as usual according to your physician’s instructions, unless your treating physician has told you to stop them.

• Hormone tests: For some hormones, it is essential to observe the specified day of the menstrual cycle or the time of collection. For example, 8 a.m. cortisol or midnight salivary cortisol must be done at the time specified by your physician.

Factors that can cause bruising at the blood draw site:

• Massaging the puncture site

• Not applying gentle pressure to the site for at least 5 minutes afterward

• Clothing with tight sleeves

• Moving the arm during the blood draw

• Sample collection in elderly patients

• Lack of a suitable vein

• Use of blood-thinning medications

• Diseases related to coagulation disorders

• Liver diseases

• Vitamin K deficiency

• Low platelet count

• Placing a bag strap over the collection site, or carrying heavy objects with the arm from which the sample was taken