Age-dependent changes in thiamin concentrations in whole blood and cerebrospinal fluid in infants and children.

We determined pediatric age-specific normative ranges for total, phosphorylated, and nonphosphorylated thiamin in whole blood (n = 323) and cerebrospinal fluid (CSF; n = 208). Whole-blood total thiamin decreased from 258 +/- 63 (mean +/- SD; age 0-3 mo group) to 214 +/- 44 nmol/L (age 3-12 mo group) in the first year of life and was stable at 187 +/- 39 nmol/L after 12 mo of age. The overall decline in whole-blood total thiamin was mainly due to a drop in phosphorylated thiamin, the biologically active form. Mean CSF total thiamin decreased from 135 +/- 42 (age 0-9-mo group) to 107 +/- 34 nmol/L (age 9-18-mo group) in the first 1.5 y of life and was stable at 84 +/- 51 nmol/L thereafter. This overall decline was due initially to a drop in nonphosphorylated thiamin and later to a drop in phosphorylated thiamin. The changes in whole blood and CSF occurred independently and probably represent metabolic and neurological maturation of the infant. Whole-blood total and phosphorylated thiamin concentrations were lower in blacks only after pubarche. Age-specific norms should be used for determining the thiamin status in infancy because thiamin concentrations are significantly higher in the first few months of life.