الفهرس 
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Abstract
Neonatal jaundice or hyperbilirubinemia is the most common disease in newborn infants. It has been estimated that 60% of term ba-bies and 80% of preterm babies develop jaundice in their first week of life. The yellowish discoloration of the skin and sclera in newborns is due to accumulation of unconjugated bilirubin.
Phototherapy is the safest and commonly used treatment option for neonatal jaundice. It converts indirect bilirubin to water-soluble stereoisomers by a process called photo-isomerization. However, this treatment modality may itself result in the development of some com-plications.
There was a positive relation between serum Mg and bilirubin levels and propounded that rising of Mg in hyperbilirubinemia might be a compensatory mechanism against toxic effects of bilirubin.
Bilirubin exhibits an affinity for the phospholipids of the plasma membrane, such as the N-Methyl-D-Aspartate (NMDA) receptors. Magnesium is an NMDA antagonist, which could decrease the neuro-toxic effects of bilirubin.
The aim of the work was to study the effect of phototherapy on serum magnesium levels in neonates with hyperbilirubinemia.
This prospective hospital based comparative study was con-ducted on 70 full-term neonates with indirect hyperbilirubinemia ad-mitted in Neonatal Intensive Care Units of Menoufia University Hos-pital and subjected to phototherapy. Each neonate was subjected to de-tailed history taking and clinical examination, which included general and local examination.
Summary
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Base line investigations were done at admission complete Blood Count, Rh and blood grouping for mothers and babies, reticulocyte count, C-reactive protein, liver function test and coomb’s test. Serial measurements of total serum bilirubin levels and also serum magnesi-um levels (total – ionized) were measured at admission, 48 hours after phototherapy and at discharge.
The study included 42 males (60%) and 28 females (40%). 45 were delivered by CS (64.3%), while 25 delivered by NVD (35.7%). Mean age of the studied group was 5.1 ± 1.1 days, mean gestational age was 39 ± 0.7 weeks and mean birth weight was 3.2 Kg. Causes of jaundice were due to breast feeding failure (28.6 %), breast milk (14.3 %) and exaggerated physiologic (57.1 %).
The mean levels of total leukocytic count before phototherapy were (12.5±1.7) and after phototherapy were (13.6±1.4) so there was statistically significant increase in total Leukocytic count (cells/cm3) in neonates after phototherapy compared to before phototherapy.
The mean levels of platelets count before phototherapy were (270.9±50.9) and after phototherapy were (261.5±52.1) so there was statistically significant decrease in platelets after phototherapy com-pared to before phototherapy.
The mean levels of calcium before phototherapy were (9.34 ± 0.29) and after phototherapy were (8.5 ± 0.29) so there was statistical-ly significant decrease in calcium after phototherapy compared to be-fore phototherapy.
On the other hand, there was no significant difference in hemo-globin (g/dl), blood urea, serum creatinine, HCT, reticulocytes, CRP, ALT and AST.
Summary
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The mean of total serum bilirubin level before starting photo-therapy was (16.48± 1.36 mg/dl), 48 hours after phototherapy was (12.5 ±1.0 mg/dl), whereas after termination of phototherapy was (8.73 ± .70 mg/dl). There was a significant decrease in the total serum bilirubin level after phototherapy compared to before starting photo-therapy (P < 0.001). With respect to the serum magnesium levels, the mean of total serum magnesium level before starting phototherapy was (2.7± 0.3mg/dl), 48 hours after phototherapy was (2.1 ± 0.30 mg/dl), whereas after termination of phototherapy was (1.85 ± 0.28 mg/dl). The mean of ionized serum magnesium level before starting phototherapy was (.58± 0.02mg/dl), 48 hours after phototherapy was (.53 ± 0.02 mg/dl), whereas after termination of phototherapy was (51 ± 0.01 mg/dl). There was a significant decrease in serum magnesium (total and ionized) after phototherapy compared to before starting pho-totherapy (P < 0.001).
We found that there was a statistically significant positive corre-lation between total bilirubin and magnesium (total and ionized) in all studied neonates. There was a statistically significant negative correla-tion between (total, ionized) magnesium and duration of phototherapy.
Phototherapy reduces bilirubin as a result of this, the movement of magnesium from intracellular to extracellular is stopped and this leads to decrease in the plasma ionized magnesium and serum magne-sium also.
Phototherapy leads to inhibition of pineal gland via transcranial illumination, resulting in a decline in melatonin level and this leads to increase corticosterone. Corticosterone increases calcium absorption by bone. Hence the increase in the level of corticosterone leads to hy-pocalcemia and hypomagnesemia.