Menoufia Medical Journal

ORIGINAL ARTICLE
Year
: 2015  |  Volume : 28  |  Issue : 2  |  Page : 426--430

Effect of phototherapy on serum calcium level in neonatal jaundice


Mohammed Hamed Bahbah1, Fathia Mohamed ElNemr1, Rania Salah ElZayat1, Elham Aziz Khalid Aziz2,  
1 Department of Pediatrics, Faculty of Medicine, Menoufia University, Menoufia, Egypt
2 Department of Pediatrics, Tala Central Hospital, Menoufia, Egypt

Correspondence Address:
Elham Aziz Khalid Aziz
Department of Pediatrics, Tala Central Hospital, Menoufia
Egypt

Abstract

Objectives The aim of the study was to determine the effect of phototherapy on serum calcium level in neonatal jaundice. Background Phototherapy plays a significant role in the treatment and prevention of hyperbilirubinemia in neonates. However, this treatment modality may result in the development of some complications such as induction of hypocalcemia. Patients and methods This study included 50 full-term neonates with jaundice (25 males and 25 females) who received phototherapy for treatment of neonatal indirect hyperbilirubinemia and 25 neonates (13 males and 12 females) complaining of exaggerated physiological hyperbilirubinemia taken as control not exposed to phototherapy. Serum calcium was checked before and 48 h after starting phototherapy. A comparative study was conducted between these groups to determine the effect of phototherapy on serum calcium level. Results In the neonates of the study group, the serum bilirubin level before phototherapy was 15.48 ± 1.94 mg/dl. However, the serum bilirubin level after phototherapy was 12.41 ± 2.10 mg/dl. There was highly statistically significant decrease of the serum bilirubin levels after phototherapy as compared with serum bilirubin levels before phototherapy in the study group (P < 0.001). With respect to the calcium level, the total serum calcium level before phototherapy was 9.36 ± 0.29 mg/dl, whereas the serum calcium level after phototherapy was 8.58 ± 0.76 mg/dl. There was highly statistically significant decrease of the serum calcium levels after phototherapy as compared with serum calcium levels before phototherapy in the study group. Conclusion Hypocalcemia is a common complication of phototherapy.



How to cite this article:
Bahbah MH, ElNemr FM, ElZayat RS, Aziz EA. Effect of phototherapy on serum calcium level in neonatal jaundice.Menoufia Med J 2015;28:426-430


How to cite this URL:
Bahbah MH, ElNemr FM, ElZayat RS, Aziz EA. Effect of phototherapy on serum calcium level in neonatal jaundice. Menoufia Med J [serial online] 2015 [cited 2019 Jul 19 ];28:426-430
Available from: http://www.mmj.eg.net/text.asp?2015/28/2/426/163896


Full Text

 Introduction



Hyperbilirubinemia is the most common abnormal physical finding in the first week of life in neonates and is observed in ~60% of term neonates and 80% of preterm infants [1] . In Egypt, about 20.4% develop jaundice yearly. Incidence of jaundice was found to be higher in low birth weight neonates (35.6%) compared with normal birth weight infants (16.9%) [2] . Although most infants with jaundice are otherwise perfectly healthy, they make us anxious because bilirubin is potentially toxic to the central nervous system [3] .

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 [4] .

The effectiveness of phototherapy depends upon the type of light source used (i.e. dose, spectral emission curve, depth of penetration), the distance between the light and the infant, the surface area treated, the etiology of the jaundice, and total serum bilirubin level at the onset of phototherapy [5] . However, this treatment modality may itself result in the development of some complications. 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 [6] .

Melatonin stimulates secretion of corticosterone, which decreases calcium absorption by bones. Phototherapy leads to inhibition of pineal gland by transcranial illumination, resulting in a decline in melatonin level and as a result, hypocalcemia develops [7] .

The aim of the work was to study the effect of phototherapy on serum calcium level in neonatal jaundice.

 Patients and methods



This study was conducted on 50 full-term neonates with jaundice (25 males and 25 females) who received phototherapy for treatment of neonatal indirect hyperbilirubinemia (exaggerated physiological jaundice) and 25 neonates (13 males and 12 females) complaining of physiological hyperbilirubinemia taken as controls not exposed to phototherapy.

Cases were selected from those admitted to neonatal ICU of Tala Hospital, and controls were selected from outpatient clinic.

After approval of the ethical committee, informed consents were obtained from the parents of the selected neonates.

All cases chosen fulfilled the following criteria.

Icteric stable neonates.Neonates who required management with phototherapy (exaggerated physiological jaundice).Fed with full strength formula or breast fed.We excluded any neonates suffering from birth asphyxia, congenital malformation, septicemia, and hypothyroidism, infant of diabetic mother, hemolytic anemia, any newborn needing exchange transfusion, neonatal hypocalcemia, or ABO or Rh incompatibility.

The neonates in the control group were babies who had physiological neonatal jaundice managed without phototherapy or exchange transfusion.

In contrast, patients in the studied group were placed under phototherapy. The phototherapy unit used was four blue light lamps, 20 W, which supplies spectral irradiance of 5 mW/cm 2 /nm at 450-470 nm/cm 2 . Naked neonates were placed while covering eyes and genitalia at a distance of 45-50 cm from phototherapy unit and were managed with continuous phototherapy in open bed. The position of the baby was changed from time to time.

Each case was subjected to detailed history taking (gestational age, mode of delivery, detailed prenatal and natal history, age on admission, and day of onset of jaundice and family history of neonatal jaundice) and clinical examination, which included general and local examination with special emphasis on weight, length, head circumference, and manifestations of hypocalcemia (jitteriness, irritability, and convulsion).

Laboratory investigations were applied including total serum bilirubin before and 48 h after phototherapy, total serum calcium before and after 48 h after starting of phototherapy, blood group to infant and mother, reticulocytic count, and hemoglobin level. Thereafter, all data were tabulated and analyzed statistically to detect hypocalcemia as a complication of phototherapy.

Statistical data analysis

Statistical presentation and analysis of the present study was conducted by SPSS, V. 20. Quantitative data were analyzed by the Student t-test and paired t-test. Qualitative data were analyzed by the χ2 -test and Fisher's exact test. The test is considered significant when P value is less than 0.05.

 Results



The study group included 50 neonates, 25 boys (50%) and 25 girls (50%), with mean gestational age of 38.28 ± 0.99 weeks and mean postnatal age 4.26 ± 1.12 days. There were 20 neonates (40%) delivered by normal vaginal delivery and 30 neonates (50%) delivered by Cesarean section [Table 1].

There was no statistically significant difference between both groups regarding gestational age, postnatal age, sex, and mode of delivery (P > 0.05) [Table 2].{Table 1}{Table 2}

All cases of the study group presenting with neonatal hyperbilirubinemia were managed with phototherapy only and closely observed for the possibility of developing phototherapy-induced hypocalcemia.

The serum bilirubin level among neonates of the study group was 15.4 ± 1.94 mg/dl, whereas the serum bilirubin level among the neonates of the control group was 6.6 ± 0.79 mg/dl. There was highly statistical significant difference between both studied groups regarding total serum bilirubin level (P < 0.001) [Table 3].{Table 3}

The serum calcium level of neonates of the study group before phototherapy was 9.3 ± 0.29 mg/dl. However, the serum calcium level among neonates of the control group was 9.1 ± 1.29 mg/dl. There was no statistical significant difference between both studied groups regarding total serum calcium level on arrival (P > 0.05).

In the neonates of the study group, the serum bilirubin level before phototherapy was 15.4 ± 1.94 mg/dl, whereas the serum bilirubin level after phototherapy was 12.4 ± 2.10 mg/dl. There was highly statistically significant decrease of the serum bilirubin levels after phototherapy, as compared with serum bilirubin levels before phototherapy in the study group (P < 0.001) [Table 4].{Table 4}

With respect to the calcium level, the total serum calcium level before phototherapy was 9.3 ± 0.29 mg/dl, whereas the serum calcium level before phototherapy was 8.5 ± 0.76 mg/dl. There was highly statistically significant decrease of the serum calcium levels after phototherapy, as compared with serum calcium levels before phototherapy in the study group (P<0.001) [Table 4].

Neonates with hypocalcemia represented 13 cases (26%) and those with normal calcium represented 37 cases (74%). Neonates with jitteriness represented seven cases (14%) and those with convulsions represented five cases (10%) of hypocalcemic neonates [Table 5].{Table 5}

The severity of hypocalcemia in hypocalcemic neonates was 61.5% mild and 38.5% severe [Table 6], [Figure 1] and [Figure 2]).{Table 6}{Figure 1}{Figure 2}

 Discussion



In our study, the first group (jaundiced neonates treated with phototherapy as the study group with bilirubin level 15.4 ± 1.94 mg/dl) included 50 neonates, 25 boys (50%) and 25 girls (50%) with mean gestational age 38.28 weeks. The second group (physiological jaundiced neonates treated without phototherapy as the control group with bilirubin level 6.6 ± 0.79 mg/dl) included 25 neonates, 13 boys (52%) and 12 girls (48%) with mean gestational age 38.7 weeks.

In our study, hypocalcemia was assessed as a complication of phototherapy in newborns managed for neonatal hyperbilirubinemia.

Before phototherapy, there was no statistically significant difference between serum calcium level in cases (9.3 mg/dl) and in controls (9.18 mg/dl). However, after 48 h of treatment of cases with phototherapy, serum calcium level decreased to 8.5 mg/dl, and we found highly statistically significant difference between serum calcium level before and after exposure to phototherapy where P value was less than 0.01.

This was in agreement with several previous studies.

In studies by Karamifar et al. [7] and Ehsanipour et al. [6] the incidence of hypocalcemia after 48 h of phototherapy was 15 and 14.4%, respectively.

In addition, Jain et al. [8] noticed that 55% of preterm neonates and 30% of full-term neonates developed hypocalcemia after being subjected to phototherapy.

In addition, Sethi et.al. [9] noticed hypocalcemia after 48 h of phototherapy. Sixty neonates with hyperbilirubinemia were included in their study. There were 20 preterm (group A) and 20 full-term (group B) neonates. Ten neonates from each group formed the control group. The study group neonates were managed with phototherapy, whereas the control group neonates were not subjected to phototherapy. Serum calcium levels of the two groups were studied. In all, 90% preterm neonates and 75% full-term neonates developed hypocalcemia after being subjected to phototherapy. There was a highly significant decrease in total as well as ionized calcium levels in the study group in contrast to the control group. They recommended that neonates under phototherapy should be given supplemental calcium to prevent hypocalcemia.

Mostafa et al. [10] also found hypocalcemia after exposure to phototherapy, with a higher percentage among the preterm neonates, as compared with full-term neonates.

The etiology of hypocalcemia in infants treated with phototherapy is believed to be caused by a decrease in melatonin level and corticosterone secretion [7] . In addition, urinary calcium excretion is increased after exposure to phototherapy [11] .

This decrease in calcium can be explained by melatonin secretion [12] . Melatonin stimulates secretion of corticosterone, which decreases calcium absorption by bones. Phototherapy leads to inhibition of pineal gland by transcranial illumination, resulting in a decline in melatonin level and as a result, hypocalcemia develops [7] . Cortisol exerts a direct hypocalcemic effect by decreasing the absorption of Ca and PO 4 ions from the intestine by antivitamin D action and by increasing the renal excretion of these ions and also accelerates the bone uptake of calcium [13] .

In addition, urinary calcium excretion is increased after exposure to phototherapy as shown by Hooman and Honarpisheh [11] .

The reason for a higher incidence of hypocalcemia in preterm infants is still unknown.

Prevention of hypocalcemia in infants undergoing phototherapy has been trialed by this research group and others. The researchers studied 100 preterm newborns to verify whether calcifediol (25(OH)D3) could be useful to prevent the phototherapy-induced hypocalcemia. Results obtained show that calcifediol is not able, anyway, to lower the increase of the phototherapy-induced hypocalcemia in preterm infants. Vitamin D is therefore unlikely to play any important role in the pathogenesis of phototherapy-induced hypocalcemia [12] . Zecca et al. [12] also found that vitamin (25(OH)D3) is ineffective in the prevention of hypocalcemia induced by phototherapy in newborns.

Suggestions to possibly prevent development of hypocalcemia in phototherapy-treated newborn include either giving them oral calcium as prophylaxis or covering their heads and occipital area using a special hat during phototherapy, so that light effect from phototherapy on newborns' pineal gland and consequently melatonin decreases and hypocalcemia can be prevented [7] .

No researchers demonstrated symptomatic hypocalcemia in infants treated with phototherapy.

 Conclusion



Hypocalcemia is a complication of phototherapy. However, the clinical relevance of this finding needs further study.

 Acknowledgements



Conflicts of interest

There are no conflicts of interest.

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