the microsampling blog

pediatric blood draw limits: how much is safe

In pediatric medicine, for screening and other purposes, it is important to know the appropriate amount of blood that can be drawn from a child depending on their age. The younger they are, the less their blood volume. In cases of newborn screening, if too much blood is drawn, there is a risk of losing an infant.


How Much Is Safe

The question of how much is safe varies depending on one major factor which is the age of the child from whom the blood is drawn. According to research on safe blood draws in infants, it is recommended by several studies and guidelines that the maximum amount of blood drawn from infants and children in 24 hours be between 1% and 5% of the total blood volume (TBV) of the child. Ideally, the amount should be less than 3% of the TBV. With the use of microsampling, this is easy to achieve. For sick children, only 3.8% of the total blood volume should be drawn within 24 hours. The research further highlights that only 10% of the total blood volume can be drawn from the child over a period of eight weeks.

The Dried Blood Alternative

These limits are recommended for effective coordination in clinical research activities and in medical laboratory tests to minimize the burden on the child.

There are a number of ways in which blood is drawn from children. Some of this includes the use of new advanced methods such as microsampling. For newborns, the pediatrician pricks the heel, a process known as heel prick, allowing the collection of a few drops of blood, which is then used to test all the disorders. The process of pricking the heel and drawing one or two drops of blood is also known as capillary blood sampling.

Advantages of Capillary Blood Sampling

  • The method is simple in the collection of blood therefore minimal skills are required for the procedure.
  • It is hard and relatively traumatic finding a vein for both the laboratory technician and the infant. Since the procedure is relatively painless, it makes the collection of blood less traumatic.
  • The procedure is less invasive compared to venipuncture.
  • Very little blood is collected, making this method safer for children.

click to download case studies demonstrating the successful use of blood microsampling vulnerable populations

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