First let’s talk about the methodology. 

• Dried blood samples are collected by a finger prick 
• They are a mix of capillary blood, arterial blood, interstitial fluid and extracellular fluid
• This is how we test new born babies – it’s not only a functional medicine thing
• This method of testing has been extensively studied in clinical research, in community settings and is routinely used in toxicology, forensic, and post mortem testing. 

How accurate is it?

Let’s break it down by nutrient at a clinical level.

Vitamin A: 

DBS retinol is precise and comparable to plasma and serum retinol. It’s stable in storage for 90 days. 

B Vitamins:

DBS B1 Has been validated for assessing thiamine deficiency in infants and found comparable to venous blood.

DBS B1,B2 and B6 (PLP) Have been validated in children, and found good agreement with the corresponding correlations in liquid blood.

DBS B5 (5-methyltetrahydrofolic acid) or 5-MTHF Has been validated and found comparable to whole blood and plasma folate in healthy controls and subjects with MTHFR genotypes. DBS space B5 (pantothenic acid) has been measured in metobonomic studies for newborn screenings. 

Vitamin C:

DBS vitamin C What is compared to venous samples and the difference was found to be less than 5%

Vitamin D:

DBS vitamin D3 has been found comparable to serum and plasma D3 levels

Vitamin E:

DBS alpha to cover all technique is simple, rapid, specific, accurate, precise, and reproducible. It can be useful in field based epidemiological studies.

Glutathione (GSH):

DBS technique determined total GSH is comparable to venous blood. Mass screening of newborns for DBS reduced GSH and GSH disulphide is used to detect Glucose – 6 – phosphate dehydrogenase (G6PD) deficiency. Additionally, glutathione – S – transferase has been measured in DBS proteomics analysis. 

Carnitine: 

DBS L- Carnitine has been measured in DBS newborn screenings for amino, organic, and fatty acid disorders. 

MMA:

DBS MMA has been validated in adult women and shown high linearity with plasma MMA, with concentration stable in storage at one year.

Minerals: 

DBS calcium, Manganese, zinc, copper, chromium, iron, magnesium, and selenium have been quantified in newborn screenings.

Amino Acids (AA):

DBS testing has long-being used nationally and globally in newborn screenings for inborn errors of metabolism and malnutrition. Stability studies of DBS AA’s have  found AA’s were stable after 4 hours even in direct sunlight exposure and after storage for 30 days there was less than 10% loss. 

For those who are skeptical, it’s easy to see that the accuracy is there. So what are you waiting for?