Normal fibronectin levels as a function of age in the pediatric population.

Fibronectin is an important non-immune opsonic protein influencing phagocytic clearance of blood-borne nonbacterial particulates which may arise in association with septic shock, tissue injury, and intravascular coagulation. In the present study, serum fibronectin was measured by both electroimmunoassay as well as rapid immunoturbidimetric assay in healthy children (n = 114) ranging in age from 1 month to 15 years in order to delineate the temporal alterations in fibronectin with age. Normal adult serum fibronectin concentrations are typically 220 micrograms/ml +/- 20 micrograms/ml. Serum concentration is 35-40% lower than normal plasma concentration due to the binding of fibronectin to fibrin during clot formation. Children between 1-12 months of age had significantly (P less than 0.05) lower serum fibronectin levels than children between the ages of 1-15 years. Progressive elevation in fibronectin levels was observed within the last 8 months of the first year of age. Fibronectin levels in children older than 1 year of age remained constant up to 15 years and were within the lower limit of the normal adult concentration. No significant (P greater than 0.05) difference in serum fibronectin was observed between male and female children at all age groups. Fibronectin levels thus, increase during the first year of age and normal levels of this blood protein in the infant are less than the normal range for adults.