الفهرس 
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Abstract
Neonatal jaundice is the most common problem in neonates. Bilirubin is toxic to the brain. It appears to distribute differentially to brain subcellular compartments and is oxidized in brain by an enzyme localized on the inner mitochondrial membrane. The enzyme is cytochrome c-dependent. It is not clear whether the activity of this enzyme serves a brain-protective effect in severe hyperbilirubinemia.
Phototherapy plays a significant role in the treatment and prevention of hyperbilirubinemia in neonates. This relatively common therapy lowers the serum bilirubin level by transforming bilirubin into water-soluble isomers that can be eliminated without conjugation in the liver.
However, this treatment modality may itself result in the development of some complication. Among these are loose stools, erythematous macular rash, overheating, dehydration, damage to DNA, retinal injury and a benign condition called bronze baby syndrome in cholestasis.
New therapeutic methods appear to be necessary to decrease elevated serum bilirubin. One of the possible therapies for preventing bilirubin neurotoxicity is via reducing the unconjugated bilirubin level by inhibition of enterohepatic circulation.
Zinc salts have a potential to inhibit enterohepatic circulation of bilirubin probably by precipitating unconjugated bilirubin in the intestine.
The aim of this work was to evaluate serum zinc level as a short term hazards of phototherapy in hospitalized jaundiced neonates.
The study was conducted on 140 neonates from neonatal intensive care unit of Menoufia university hospitals, Ashmoon general hospital and outpatient. Neonates were allocated in 2 groups:
- group 1: included 100 jaundiced neonates (81 full-term &19 preterm) whom required phototherapy as a treatment for jaundice.
- group 2: included 40 jaundiced neonates (20 full-term &20 preterm) not treated with phototherapy as the control group.
All patients were subjected to the following after taking a written consent from the parents of them:
1. Full and detailed history
2. Full examination
3. Laboratory investigations including complete blood count, C - reactive protein, blood grouping and reticulocyte counting. Also total, direct serum bilirubin and serum zinc level (before and 72 hours after phototherapy).
In our study, elevated serum zinc was assessed as short term hazard of phototherapy used to treat neonates with indirect hyperbilirubinemia.
Before phototherapy, there was no statistically significant difference between serum zinc level in studied cases (71.34±12.11mcg/dl) and in control (72.7±11.01mcg/dl). But after 72 hours of treatment with phototherapy, serum zinc level increased to (140.5±64.3mcg/dl) in cases. We found highly statistically significant difference between serum zinc before and after exposure to phototherapy with P value <0.001.
So we conclude that phototherapy increases serum zinc level by reducing bilirubin level so that additional supplementation of this element can lead potentially to zinc toxicity. And so we recommend that neonates should be evaluated for serum zinc level after 72 hours from continuous phototherapy.
Accordingly, it appears that using soluble zinc salts that can be absorbed into the blood system is not safe in hyperbilirubinemic neonates. Therefore we conclude that future studies on inhibiting bilirubin enterohepatic circulation in hyperbilirubinemic neonates could be done with insoluble zinc salts.