The effect of common blood sampling types on metabolic screening.

Area of Science:

• Biochemistry
• Clinical Chemistry
• Mass Spectrometry

Background:

• Capillary blood is frequently utilized for dried blood spot (DBS) samples in metabolic screening.
• Variations in blood collection methods may influence analyte concentrations in DBS testing.
• Standardization of sample collection is crucial for accurate metabolic screening results.

Purpose of the Study:

• To investigate and compare amino acid and acylcarnitine levels in different blood sampling types.
• To evaluate findings against capillary whole blood samples as the reference standard.
• To assess the impact of various collection tubes on metabolic screening analytes.

Main Methods:

• Blood samples from 30 adult participants were collected into citrated, serum separating, heparin, and EDTA tubes, as well as a syringe.
• 50 μL of blood from each collection method was absorbed onto filter papers for DBS analysis.
• Capillary whole blood from fingertip punctures was also absorbed onto filter paper.
• All samples were analyzed using flow-injection analysis tandem mass spectrometry (FIA-MS/MS).

Main Results:

• Almost all measured amino acid and acylcarnitine levels differed significantly (p < 0.05) between the fingertip DBS group and samples from other collection tubes.
• Glutamine and methionine were exceptions, showing no significant difference in amino acid levels.
• Differences in acylcarnitine levels were less pronounced than those observed for amino acids.

Conclusions:

• Using alternative blood sampling types instead of capillary whole blood for metabolic screening can lead to inaccurate, particularly lower, results, especially for amino acids.
• Laboratory cut-off values for metabolic screening must consider the specific blood sampling type used.
• Clear communication regarding the sampling method employed is essential for accurate interpretation of DBS test results.