Newborn screening (PKU), Minnesota-S3620.0

Test info

Newborn screening (PKU), Minnesota

Newborn Screening (NBS) tests for 50 disorders that may affect an infant's metabolism, endocrine system, blood, breathing, hearing, or digestion




Patient should be between 24 and 48 hours of age

Blood spots

Blood spots are best collected between 24 and 48 hours of age. Blood spots collected before 24 hours of age cannot be fully interpreted, which means some test results will be marked “unsatisfactory” on the newborn screening report.

  1. Ensure that the expiration date of the newborn screening card has not passed. Complete the required patient information fields requested on the demographic data portion of the card. Avoid touching the area within the circles on the filter paper section before, during, and after collection of the specimen, since oils and other materials from the hands might affect or contaminate the card or specimen.
  2. Blood collection from the heel is the standard for newborn screening. The medial and lateral parts of the underfoot are preferred.
  3. Warm the heel with a heel warmer and position the leg lower than the heart to increase venous pressure before collecting the blood spots. The infant should be swaddled in a blanket with only one foot exposed. Wipe the skin clean with an alcohol wipe and allow to thoroughly air dry.
  4. Use a sterile lancet or heel incision device to make an incision 1mm deep and 2.5mm long. When collecting from small, premature infants, it is safer to make a more shallow incision.
  5. Wipe away the first drop of blood with a sterile gauze pad. Allow a large drop of blood to form. Using the thumb to intermittently apply gentle pressure to the heel may be helpful in encouraging the drop to coalesce.
  6. Touch the first circle on the newborn screening card gently against the large blood drop, and in one step, allow the blood to soak through the filter paper and fill the circle. Do not press the paper directly against the baby’s heel. Each of the five circles needs to be filled and saturated through. Apply the blood from only one side of the filter paper. It does not matter whether the blood is applied to the front or back of the filter paper.
  7. Do not apply multiple layers of blood drops to the same circle. Excessive milking or squeezing of the puncture site can result in an unsatisfactory specimen because of hemolysis breaking down the blood cells to be analyzed or mixing tissue fluids in the specimen, which can dilute the blood.

Simple spot check; Satisfactory and unsatisfactory specimens


Dry flat for a minimum of 3 hours


Newborn screening (PKU) card (MN)


Ambient - within 24 hours of collection


MN Department of Health (MDH)
Mo - Sa
14 days


Clinical and Interpretive info


See report