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Zinc protoporphyrin (ZnPP) is a normal metabolite that is formed in trace amounts during heme biosynthesis. The final reaction in the biosynthetic pathway of heme is the chelation of iron with protoporphyrin. During periods of iron insufficiency or impaired iron utilization, zinc becomes an alternative metal substrate for ferrochelatase, leading to increased ZnPP formation. Evidence suggests that this metal substitution is one of the first biochemical responses to iron depletion, causing increased ZnPP to appear in circulating erythrocytes. Because this zinc-for-iron substitution occurs predominantly within the bone marrow, the ZnPP/heme ratio in erythrocytes reflects iron status in the bone marrow. In addition, ZnPP may regulate heme catabolism through competitive inhibition of heme oxygenase, the rate-limiting enzyme in the heme degradation pathway that produces bilirubin and carbon monoxide. Physiological roles, especially relating to carbon monoxide and possibly nitric oxide production, have been suggested for ZnPP. Clinically, ZnPP quantification is valuable as a sensitive and specific tool for evaluating iron nutrition and metabolism. Diagnostic determinations are applicable in a variety of clinical settings, including pediatrics, obstetrics, and blood banking. ZnPP analytical methodologies for clinical studies are discussed. In addition to diagnostic tests and metabolic studies, ZnPP has a potential therapeutic application in controlling bilirubin formation in neonates as a preventive measure for hyperbilirubinemia. Biochemical research techniques, both in vivo and in vitro, are described for further studies into the role of ZnPP in metabolism and physiology.

We summarize the treatment of 20 patients with Crigler-Najjar disease (CND) managed at one center from 1989 to 2005 (200 patient-years). Diagnosis was confirmed by sequencing the UGTA1A gene. Nineteen patients had a severe (type 1) phenotype. Major treatment goals were to maintain the bilirubin to albumin concentration ratio at <0.5 in neonates and <0.7 in older children and adults, to avoid drugs known to displace bilirubin from albumin, and to manage temporary exacerbations of hyperbilirubinemia caused by illness or gallstones. A variety of phototherapy systems provided high irradiance over a large body surface. Mean total bilirubin for the group was 16+/-5 mg/dl and increased with age by approximately 0.8 mg/dl per year. The molar ratio of bilirubin to albumin ranged from 0.17 to 0.75 (mean: 0.44). The overall non-surgical hospitalization rate was 0.12 hospitalizations per patient per year; one-half of these were for neonatal hyperbilirubinemia and the remainder were for infectious illnesses. Ten patients (50%) underwent elective laproscopic cholecystectomy for cholelithiasis. No patient required invasive bilirubin removal or developed bilirubin-induced neurological damage under our care. Visual acuity and color discrimination did not differ between CND patients and age-matched sibling controls. Four patients treated with orthotopic liver transplantation were effectively cured of CND, although one suffered significant transplant-related complications.Conclusions. While patients await liver transplantation for CND, hyperbilirubinemia can be managed safely and effectively to prevent kernicterus. Lessons learned from CND can be applied to screening and therapy of non-hemolytic jaundice in otherwise healthy newborns.

OBJECTIVE:To determine the efficacy of blue versus blue-green phototherapy using new light sources with narrow luminous spectra. The devices made of highintensity gallium nitride light-emitting diodes (LEDs) were also compared to conventional halogen-quartz bulbs phototherapy. DESIGN:Prospective open randomized study. PARTICIPANTS:A total of 114 jaundiced, but otherwise healthy term infants who met the entry criteria for phototherapy set by the American Academy of Pediatrics' Practice Parameter. MAIN OUTCOME MEASURES:The duration of phototherapy and the rate of decrease in total serum bilirubin (TSB). RESULTS:The mean TSB concentrations at initiation and termination of treatment, as well as the duration of phototherapy and the rate of decrease in TSB, were not statistically different in newborns receiving blue LED, blue-green LED or conventional phototherapy. The average rate of decrease in TSB (slope), after adjustment by a linear regression analysis for confounding factors, was À3.61 mmol/hour (95% confidence limits À5.47, À1.75) in the 25 newborns receiving blue LED phototherapy compared with À2.57 mmol/hour (À4.32, À0.82) in the 22 newborns treated with bluegreen LED phototherapy and À3.42 mmol/hour (À5.02, À1.81) in the 57 newborns who received conventional phototherapy. CONCLUSIONS:When using low light irradiance, there was no statistically significant difference in the effectiveness of phototherapy using blue-green LEDs, blue LEDs or conventional halogen-quartz bulbs.

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This prospective cohort study supports previous observations that measuring STB before discharge may provide some assistance in predicting an infant's risk for developing hyperbilirubinemia. The addition of an ETCOc measurement provides insight into the processes that contribute to the condition but does not materially improve the predictive ability of an hours of age-specific STB in this study population. The combination of STB and ETCOc as early as 30+/-6 hours may identify infants with increased bilirubin production (eg, hemolysis) or decreased elimination (conjugation defects) as well as infants who require early follow-up after discharge for jaundice or other clinical problems such as late anemia. Depending on the incidence of hyperbilirubinemia within an institution, the criteria for decision making should vary according to its unique population.

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