Neonatal jaundice

Early corticosteroid treatment does not affect severity of unconjugated hyperbilirubinemia in extreme low birth weight preterm infants

AIM

To determine the relationship between early postnatal dexamethasone (DXM) treatment and the severity of hyperbilirubinemia in extreme low birth weight (ELBW) preterm infants.

METHODS

In 54 ELBW preterm infants, total serum bilirubin concentrations (TSB) and phototherapy (PT) data during the first 10 days were evaluated retrospectively. ELBW infants had participated in a randomized controlled trial of early DXM treatment which aimed to assess effects on chronic lung disease. Infants had been treated with DXM (0.25 mg/kg twice daily at postnatal day 1 and 2) or with placebo (normal saline). Analysis was performed on an intention to treat basis.

RESULTS

Twenty-five Infants had been randomized into the DXM group; 29 into the placebo group. Mean (±SD) TSB [120 (±19) μmol/L vs. 123 (±28) μmol/L, DXM versus placebo, respectively] and maximum TSB [178 (±23) μmol/L vs. 176 (±48), DXM versus placebo, respectively] concentrations were similar. TSB concentrations peaked 30 h earlier in the DXM group (p ≤ 0.05). The need for PT as well as the duration of PT was similar in both groups.

CONCLUSIONS

Early DXM treatment does not affect the severity of neonatal hyperbilirubinemia in ELBW preterm infants. Our results seem compatible with the concept that factors other than bilirubin conjugation capacity are important for the pathophysiology of neonatal jaundice in ELBW preterm infants.

Differences in transcutaneous bilirubin readings in Japanese term infants according to feeding method

BACKGROUND

Controversy has existed for many years over whether infant feeding methods are related to serum bilirubin concentrations during the first few days of life. Differences in initial jaundice patterns according to the feeding method until 72 h after birth have not been elucidated hitherto. The difference may become clear in Japanese neonates because jaundice shows a much higher peak bilirubin concentration and a later peak in Japanese neonates than in Caucasian neonates.

METHODS

In the present study, we investigated variations in the transcutaneous bilirubin reading (TcB) obtained within 72 h after birth among 177 breast-fed and 494 formula-fed healthy Japanese term neonates.

RESULTS

There was no difference between TcB in formula-fed and breast-fed infants until the first 30 h, after which time the rate of increase in TcB was lower in formula-fed infants. Among breast-fed neonates, a good linear regression between time after birth and TcB was maintained. Similarly, weight losses in breast-fed infants at 24-48 h and 48-72 h after birth were greater than those in formula-fed infants.

CONCLUSIONS

The jaundice pattern in Japanese neonates from 30 to 72 h after birth according to the feeding method was different from that in Caucasian neonates.

Intestinal colonization leading to fecal urobilinoid excretion may play a role in the pathogenesis of neonatal jaundice

BACKGROUND

Neonatal hyperbilirubinemia remains of concern because of the potential danger for the central nervous system. Because urobilinogen is a nontoxic derivative of bilirubin, the current study was conducted to examine the fecal excretion of urobilinoids and bilirubin in healthy newborns and infants, as well as their intestinal bacteria capable of reducing bilirubin, to assess a possible relation to serum bilirubin levels during the first weeks of life.

METHODS

Bilirubin pigments, urobilinoids, and porphyrins were measured in stools of infants during the first week (group A, n = 60) and between the second week and the first 6 months of life (group B, n = 64). Microbiologic analysis of stools was performed in selected cases and bilirubin-converting activity of isolated bacteria was determined in vitro.

RESULTS

Urobilinoids were detectable in stools of 57% of the neonates at day 5, but not before. However, fecal urobilinoid production on that day was only a fraction of that observed in adults (0.07 vs. 0.7-3.6 mg/kg per day), whereas at week 6 it increased significantly to an average of 0.9 mg/kg per day. Microbiologic analysis of neonatal stools revealed two novel bacterial strains of Clostridium perfringens and Clostridium difficile capable of reducing bilirubin to urobilinoids.

CONCLUSIONS

Urobilinoids can be detected in stools of 57% of newborns at day 5 after delivery. However, the urobilinoid production during the first week of life is quantitatively insufficient to contribute significantly to the removal of bilirubin. Enhancement of the microbial conversion of bilirubin could decrease the intestinal concentration of bilirubin and may decrease the degree or enhance the removal of neonatal hyperbilirubinemia.

Development of jaundice in Korean neonates after cesarean section

The aim of the project was to determine the physiologic mechanisms of later- and higher-peak transitional plasma bilirubin levels in Korean infants. Blood carboxyhemoglobin, corrected for inhaled CO (COHbc), as an index of bilirubin production, and plasma total bilirubin levels in 40 healthy term Korean infants delivered by Cesarean section were measured throughout the first week of life. The COHbc levels were significantly higher in the Korean neonates than in previously studied Caucasian neonates. Moreover, COHbc levels decreased by 28% during the first 7 days of life from 0.85 +/- 0.20 to 0.61 +/- 0.34% (P < 0.025). This pattern parallels a 15% decrease in total hemoglobin from 181 +/- 23 to 154 +/- 53 g/L (P < 0.05). In contrast, plasma bilirubin concentrations more than doubled from 80 +/- 32 to 172 +/- 48 mumol/L (4.7 +/- 1.8 to 10.0 +/- 2.8 mg/dL; P < 0.001), remaining unchanged between days 4 and 7. Both increased production and decreased elimination of bilirubin contribute to physiologic jaundice in Korean infants.

Long-term follow-up of indirect hyperbilirubinemia in full-term Turkish infants

OBJECTIVE

This retrospective follow-up study was performed to evaluate the suitability of the recently reported exchange transfusion limits (serum indirect bilirubin level of 428-496 mumol/1, 25-29 mg/dl) for Turkey.

MATERIAL AND METHODS

The study groups totalled 102 children, 8-13 years of age, who had been born at term with birthweights greater than 3000 g and had been treated for indirect hyperbilirubinemia during their newborn period; the control group consisted of 27 children of the same age-group without indirect hyperbilirubinemia. Children were grouped according to their maximum serum and bilirubin levels and direct Coomb's test results. Physical and neurological examinations, visual and brainstem auditory evoked potentials and the Wechsler Intelligence Scale for children--Revised for Turkish Children were performed.

RESULTS

There was no difference between the groups with regard to mean visual and brainstem auditory evoked potential latencies. Children whose direct Coomb's tests were positive had significantly lower IQ scores and more prominent neurological abnormalities (p < 0.05). IQ scores and prominent neurological abnormalities did not differ among the other groups. Nine children had prominent neurological abnormalities associated with abnormal brainstem auditory evoked potentials. An important risk factor was the duration that the infant's serum indirect bilirubin level remained greater than 342 mumol/l (20 mg/dl).

CONCLUSION

The current limit of 342 mumol/l should continue to be used for infants whose direct Coomb's tests are positive in our country. Until better criteria for exchange transfusion other than the indirect bilirubin level are established, the current limits should also still be followed for infants whose direct Coomb's tests are negative in Turkey, where regular neonatal follow-up examinations are not satisfactory.

Duration of action and tissue distribution of zinc protoporphyrin in neonatal rats

Zinc protoporphyrin IX (ZnPP) has been shown to inhibit heme oxygenase (HO) activity effectively in vivo and has potential in the treatment of neonatal jaundice. Because this is a transitional or temporary condition lasting only several days, an effective chemopreventive agent with a relatively short duration of action would be desirable for the treatment of severe neonatal jaundice. To determine the effective duration of action of ZnPP, we administered either 40 nmol/g of body weight ZnPP or 5 microL/g body weight diluent intraperitoneally to neonatal rats 24-36 h after birth. Between 0 and 21 d after ZnPP dosing, the duration of action was investigated through measurements of serum bilirubin and hepatic and splenic HO inhibition, which were correlated to measurements of ZnPP distribution. Significant (p < 0.05) hepatic HO inhibition, ranging from 27 to 51%, was observed in the liver between 1 and 4 d after dosing, concurrent with a 23-28% reduction in serum bilirubin levels, and was associated with ZnPP tissue concentrations of 27-38 nmol/g. Splenic HO was not inhibited measurably by the much lower concentrations of ZnPP found in the spleen (2.8-20.1 nmol/g) between 0 and 21 d after dosing. Furthermore, HO isoform 1 (HO-1) induction was apparently not a confounding factor in the duration of action of ZnPP, because the modest increases in HO-1 protein levels were not sustained longer than 24 h after ZnPP administration. Our findings demonstrated that the duration of action of ZnPP in neonatal rats is less than 1 wk. The reduction in serum bilirubin levels, the short duration of action and minimal confounding effects suggest that ZnPP may be an effective chemopreventive agent for the treatment of severe neonatal jaundice.

Hyperbilirubinemia results in reduced oxidative injury in neonatal Gunn rats exposed to hyperoxia

Bilirubin is a potent antioxidant in vitro. To determine whether bilirubin also is an antioxidant in vivo, we studied markers of oxidative injury in the Gunn rat model exposed to hyperoxia. Homozygous jaundiced males were mated with heterozygous nonjaundiced females to obtain both jaundiced and nonjaundiced pups within a litter. Once delivered, the pups and their mother were placed in air (21% O2) or hyperoxia (> 95% O2) for 3 d. Both jaundiced and nonjaundiced pups were removed from the chambers daily. Animals were sacrificed and blood was drawn for determination of serum bilirubin, blood thiobarbituric acid-reactive substances (TBARS) by fluorescence assay, serum hydroperoxides, and serum protein oxidation. Tissues (liver, lung, and brain) were assayed for lipid peroxides (TBARS, conjugated dienes [CD], loss of polyunsaturated fatty acid content [PUFA]). We also measured a wide range of serum antioxidants including superoxide dismutase, catalase, glutathione, vitamins A, C, and E, and uric acid. Blood TBARS were significantly decreased in the jaundiced pups compared to the nonjaundiced pups on day 3 of hyperoxia, and blood TBARS were inversely correlated to serum bilirubin on day 3 of hyperoxia (R2 +/- .89). Similar decreases in serum lipid hydroperoxides and serum protein carbonyl content were detected in the jaundiced pups as compared to their nonjaundiced littermates. Other serum antioxidants were not increased in jaundiced animals compared to nonjaundiced animals. Relative lung weight was lower in jaundiced pups exposed to hyperoxia compared to similarly exposed nonjaundiced pups, suggesting a reduction in hyperoxia-induced lung edema. We detected no significant effects of bilirubin on parameters of lipid peroxidation in solid tissues. We conclude that serum bilirubin protects against serum oxidative damage in the first days of life in neonatal Gunn rats exposed to hyperoxia. We speculate that bilirubin is a functionally important transitional antioxidant in the circulation of human neonates and that it may be involved in modulation of injury due to hyperoxia.

Breast mild jaundice: natural history, familial incidence and late neurodevelopmental outcome of the infant

Jaundice associated with breast feeding is a frequent problem facing the paediatrician. Despite numerous reports on this subject, the natural history, familial occurrence and late neurodevelopment of children with breast milk jaundice remain unclear. The follow up of 60 infants with breast milk jaundice showed that there are two bilirubin peaks, on the 4th and 5th day and on the 14th-15th day of life. In the infants with uninterrupted breast feeding, the hyperbilirubinaemia disappeared slowly and could still be detected 12 weeks after birth. The familial incidence of 13.9%, indicating that in some cases a unique genetic factor is expressed. Late neurodevelopment or hearing defects were not observed, thus enabling the paediatrician to encourage continuation of breast feeding in most cases of healthy infants with breast milk jaundice.

Quantum yields for the cyclization and configurational isomerization of 4E,15Z-bilirubin

Extraction of a solution of bilirubin configurational isomers in chloroform with an aqueous solution of human serum albumin was found to remove selectively the 4Z,15E-isomer. This phenomenon was used to develop a method for the purification of the 4E,15Z-isomer of bilirubin. The quantum yield for the cyclization and configurational isomerization of the 4E,15Z-isomer bound to a molar excess of human serum albumin was measured at 450 and 510 nm. The quantum yield for cyclization to form lumirubin was 0.12 and 0.19 at 450 and 510 nm, respectively. The quantum yield for configurational isomerization to form 4Z,15Z-bilirubin was 0.03 and 0.05 at 450 and 510 nm. An analysis of previously published data on the quantum yield for the formation of lumirubin from 4Z, 15Z-bilirubin bound to human serum albumin suggests that all of the formation of lumirubin may occur via consecutive photochemical processes with the 4E,15Z-isomer as an intermediate.