BACKGROUND: We have shown that very-low-birth-weight (VLBW; BW≤ 1500 g) infants develop elevated plasma [R] (vitamin B2) as high as 12,000 ng/mL (normal = 50 ng/mL) during their first postnatal month. Elevated [R] develop due to dietary supplementation and immature renal function. Current neonatal hyperbilirubinemia guidelines indicate most VLBW infants will receive phototherapy, now provided via a high intensity fiberoptic pad. However, R is photoreactive and photoperoxidizes lipid membranes at wavelengths used to treat hyperbilirubinemia, uniquely exposing VLBW infants to lipid peroxide induced injury. We hypothesized that increased light exposure at higher [R] increases [LP].

METHODS: Human serum was obtained from 12 healthy, non-pregnant, non-smoking adult females. The plasma fraction was isolated by centrifugation at 4k g × 5 minutes to remove red cells and [R] added to give concentrations of 50 (control:C), 500, and 5000 ng/mL. Samples were irradiated for 0, 2, 4 and 6 hours via the fiberoptic phototherapy pad used in clinical practice. [LP] were determined by using the lipid peroxide kit from Kamiya Biomedical Company. Analysis of variance was used to analyze the data.

RESULTS: Both [R] and light exposure (LE) demonstrated independent effect on [LP], R:ρ = 0.0002, LE:ρ < 0.0001). Thefigure shows mean± SEM for each [R] at sequential LE. The highest mean [LP] (33.9±8.3 nmol/mL) was detected at[R] = 5,000 ng/mL and 6 h of LE.

figure 1

Figure 1

DISCUSSION: Both [R] and LE are independent factors that increase [LP]. Minimal [LP] was detected at 50 ng/mL, the [R] in normal, healthy infants. To minimize risk of peroxidative injury, techniques are needed to maintain VLBW [R] in the normal range.