Assessment of Changes in Serum Calcium Among Neonates Undergoing Phototherapy for Jaundice

Balan S et al | DOI: 10.65188/nurexus.1054

Page 22

Journal of MedVerse Research & Practice

ISSN: 3107-4278

Assessment of Changes in Serum Calcium Among Neonates Undergoing

Phototherapy for Jaundice

Dr. Shree Balan

, Dr. Mourish Biswa

Professor, Professor

Department of Paediatrics, PSP Medical College Hospital and Research Institute,

Kanchipuram.

Email ID: shreebalan@gmail.com,

Submission Date: 28.10.2025

Accepted Date: 23.11.2025

Published Date: 30.11.2025

DOI: 10.65188/nurexus.1054

article distributed under the terms of the Creative Commons Attribution License (CC BY 4.0), which permits

unrestricted use, distribution, and reproduction in any medium, provided the original author(s) and source are credited.

Abstract

Background: Neonatal jaundice is a common condition requiring phototherapy, which, while effective in reducing

bilirubin levels, may lead to hypocalcaemia. The decline in serum calcium during phototherapy is often overlooked

in routine neonatal care, particularly in resource-limited settings.

Methods: This prospective observational study included 100 term and late preterm neonates requiring

phototherapy based on AAP 2004 criteria. Total and ionized serum calcium levels were measured before and after

phototherapy. Clinical characteristics, bilirubin levels, duration of phototherapy, and incidence of hypocalcaemia

were analysed using IBM SPSS version 26.0. A p-value <0.05 was considered statistically significant.

Results: The mean total serum calcium significantly decreased from 9.30 ± 0.45 mg/dL to 8.55 ± 0.50 mg/dL after

phototherapy (p < 0.001). Ionized calcium also declined significantly from 4.80 ± 0.25 mg/dL to 4.40 ± 0.30 mg/dL

(p < 0.001). Overall, hypocalcaemia (<8 mg/dL) was observed in 18% of neonates. Late preterm infants showed a

higher incidence (28.6%) compared to term neonates (13.9%). Longer phototherapy duration was strongly

associated with hypocalcaemia—7.4% (<24 hours), 26.3% (24–48 hours), and 50% (>48 hours).

Conclusion: Phototherapy causes a significant reduction in both total and ionized serum calcium, with nearly one-

fifth of treated neonates developing hypocalcaemia. Preterm infants and those receiving prolonged phototherapy

are particularly vulnerable. Routine monitoring of calcium levels during phototherapy is recommended to prevent

complications and improve neonatal outcomes.

Keywords: Neonatal jaundice; Phototherapy; Serum calcium; Hypocalcemia; Ionized calcium;

Hyperbilirubinemia;

Introduction

Neonatal jaundice, characterized by elevated bilirubin levels in newborns, is one of the most frequently

encountered conditions during the neonatal period, affecting nearly 60–80% of both term and preterm

infants in their early days of life [1]. Although most cases are physiological and transient, excessive

unconjugated bilirubin can cross the immature blood–brain barrier and lead to neurotoxicity if not

identified and treated promptly [2].

Phototherapy remains the primary and most effective treatment for unconjugated hyperbilirubinemia. It

works by transforming bilirubin into water-soluble photo-isomers that can be excreted without hepatic

conjugation [3]. Its widespread use has significantly reduced the incidence of kernicterus and other

bilirubin-induced neurological complications [4]. Despite its well-recognized benefits, phototherapy is

Balan S et al | DOI: 10.65188/nurexus.1054

Page 23

also known to produce certain adverse effects.

One clinically important but often overlooked complication is hypocalcemia—a decline in serum calcium

levels following phototherapy exposure. Multiple studies have demonstrated reductions in total and

ionized calcium in neonates undergoing phototherapy [5–7]. For example, a study on term neonates

treated with LED phototherapy reported hypocalcemia in 12.5% of infants, with a significant post-therapy

fall in calcium values [5]. Similar findings have been noted in both term and preterm neonates after 24–48

hours of phototherapy [6–8]. The mechanisms proposed for this calcium decline include light-induced

suppression of melatonin release, reduced parathyroid hormone activity, and alterations in calcium

regulation due to changes in binding proteins or renal excretion [9]. Clinically, hypocalcemia may remain

asymptomatic or may present with jitteriness, irritability, seizures, or cardiac disturbances in more severe

cases [7,8].

Worldwide, neonatal jaundice continues to contribute significantly to neonatal illness, with an estimated

1.1 million infants developing severe hyperbilirubinemia annually and approximately 114,000 deaths

reported due to bilirubin-related complications [10]. While phototherapy is considered safe, the associated

risk of hypocalcemia is frequently underestimated. Studies from countries such as Iran, Egypt, and

Pakistan report post-phototherapy hypocalcemia in 7–25% of neonates, underscoring the importance of

biochemical monitoring [6,7,11].

In India, neonatal jaundice is a major cause of hospital admissions and contributes substantially to

neonatal morbidity and mortality [12]. Despite the extensive use of phototherapy, limited data exist

regarding the occurrence and clinical relevance of phototherapy-induced hypocalcemia among Indian

neonates. Available evidence suggests that this complication often goes unnoticed due to subtle or absent

symptoms, compounded by the lack of routine calcium monitoring [13].

Understanding the pattern and extent of calcium changes during phototherapy is crucial for guiding

clinical decision-making and identifying infants at risk. Factors such as duration of phototherapy,

gestational maturity, baseline bilirubin levels, and type or intensity of phototherapy may influence

calcium fluctuations [6,7]. Existing studies show considerable variability—some report significant

biochemical changes without symptoms, whereas others highlight higher susceptibility among preterm

neonates, making direct comparisons challenging [8,9].

Given that phototherapy-induced hypocalcemia is a preventable complication, timely identification of

serum calcium changes can help avert serious outcomes. This issue is particularly relevant in Indian

neonatal care settings, where the burden of jaundice is high, and calcium monitoring is not routinely

practiced. Therefore, this study aims to evaluate the effect of phototherapy on serum calcium levels in

neonates with unconjugated hyperbilirubinemia by measuring calcium values before and after

phototherapy exposure.

Materials and Methods

The present hospital-based observational prospective study was conducted over a period of 18 months in

the labour room and postnatal wards of PSP Medical College Hospital and Research Institute,

Kanchipuram. The study population consisted of newborns who developed unconjugated

hyperbilirubinemia requiring phototherapy. A total of 100 neonates were enrolled through convenience

sampling after obtaining written informed consent from their parents. Term infants between 37^0/7 and

41^6/7 weeks of gestation and late preterm infants between 34^0/7 and 36^6/7 weeks with birth weight

above 2000 grams were included, provided they fulfilled the AAP 2004 criteria for phototherapy.

Balan S et al | DOI: 10.65188/nurexus.1054

Page 24

Newborns with pre-existing hypocalcemia, a 5-minute Apgar score below 7, infants of diabetic mothers,

babies receiving intravenous calcium gluconate, syndromic neonates, high-risk infants requiring NICU

care, and those with comorbidities such as septicemia or renal dysfunction were excluded. After

enrolment, baseline demographic and clinical information were recorded, and each neonate was weighed

at 24, 48, and 72 hours of life using a calibrated digital scale to calculate the percentage of weight loss. At

72 hours, 2 ml of venous blood was collected under aseptic precautions for estimation of total serum

bilirubin using the Diazo method, and hyperbilirubinemia was classified based on AAP 2004 guidelines.

All data were compiled into case record forms, cross-verified, and entered into a master database.

Statistical analysis was performed using IBM SPSS version 26.0. Continuous variables such as weight

loss percentages and bilirubin levels were described using mean and standard deviation, while categorical

variables like gender and gestational age were presented as frequencies and percentages. The independent

t-test was used to compare mean weight loss between neonates with and without hyperbilirubinemia, and

the Chi-square test evaluated associations between categorical variables. Pearson correlation was applied

to assess the relationship between weight loss and serum bilirubin. A p-value less than 0.05 was

considered statistically significant. Ethical approval for the study was obtained from the Institutional

Ethical Committee and Institutional Research Committee of Meenakshi Medical College and Hospital,

and all procedures were conducted according to ICMR guidelines while ensuring confidentiality and

safety of the newborns.

The present study was approved by the Institutional Ethics Committee of PSP Medical College Hospital

and Research Institute (Ref No: PSPMCHRI/IEC/78432). A detailed Participant Information Sheet was

provided to all participants, and written informed consent was obtained prior to their inclusion in the

study.

Results

Table 1. Baseline Characteristics of the Study Population (N = 100)

Parameter

Category / Mean ± SD

Frequency (%)

Gestational age

Term (≥37 weeks)

72 (72%)

Late preterm (34–36⁶/₇ weeks)

28 (28%)

Gender

Male

54 (54%)

Female

46 (46%)

Birth weight (kg)

2.85 ± 0.35

—

Mode of delivery

Vaginal

62 (62%)

LSCS

38 (38%)

The baseline characteristics show that most newborns in the study were term infants (72%), with late

preterm babies forming 28% of the sample. There was a slight male predominance, with 54% males and

46% females. The average birth weight was 2.85 ± 0.35 kg, indicating a generally healthy neonatal

population. Regarding delivery mode, 62% were born through normal vaginal delivery, while 38% were

delivered by LSCS, reflecting a typical obstetric distribution in similar hospital-based studies.

Table 2. Distribution of Neonates by Total Serum Bilirubin Before Phototherapy

Total Serum Bilirubin (mg/dL)

Frequency

Percentage (%)

12–14

30%

14–16

40%

16–18

20%

Balan S et al | DOI: 10.65188/nurexus.1054

Page 25

>18

10%

Total

100

100%

The distribution of total serum bilirubin levels shows that most neonates (40%) had bilirubin levels

between 14–16 mg/dL, followed by 30% in the 12–14 mg/dL range. Higher bilirubin levels were less

common, with 20% between 16–18 mg/dL and 10% above 18 mg/dL. This pattern indicates that the

majority of newborns presented with moderate hyperbilirubinemia requiring phototherapy.

Table 3. Serum Calcium Levels Before and After Phototherapy

Parameter

Mean ± SD (Pre-

phototherapy)

Mean ± SD (Post-phototherapy)

p-value

Total serum calcium (mg/dL)

9.30 ± 0.45

8.55 ± 0.50

<0.001

Ionized calcium (mg/dL)*

4.80 ± 0.25

4.40 ± 0.30

<0.001

The comparison of calcium levels before and after phototherapy shows a significant decline in both total

and ionized serum calcium following treatment. The mean total calcium decreased from 9.30 ± 0.45

mg/dL to 8.55 ± 0.50 mg/dL, and ionized calcium dropped from 4.80 ± 0.25 mg/dL to 4.40 ± 0.30 mg/dL,

with both reductions being statistically significant (p < 0.001).

Figure 1: Incidence of Hypocalcemia After Phototherapy

Out of 100 neonates who received phototherapy, 82% maintained normal calcium levels, while 18%

developed hypocalcemia (serum calcium <8 mg/dL). This indicates that nearly one in five neonates

experienced a fall in calcium levels significant enough to be classified as hypocalcemia, highlighting the

need for biochemical monitoring during phototherapy.

Table 4. Comparison of Hypocalcemia by Gestational Age

Gestational Age

Normal Calcium (n=82)

Hypocalcemia (n=18)

Total

Term (n=72)

Late preterm (n=28)

Total

100

Balan S et al | DOI: 10.65188/nurexus.1054

Page 26

Among the 72 term neonates, 62 (86.1%) maintained normal calcium levels, while 10 (13.9%) developed

hypocalcemia. In contrast, among the 28 late preterm neonates, only 20 (71.4%) had normal calcium

levels, whereas 8 (28.6%) developed hypocalcemia.

Table 5. Association Between Duration of Phototherapy and Hypocalcemia

Duration of Phototherapy

Normal Calcium (n=82)

Hypocalcemia (n=18)

Total

<24 hours

24–48 hours

>48 hours

Total

100

Neonates who underwent phototherapy for less than 24 hours showed a low incidence of hypocalcemia,

with 4 out of 54 (7.4%) affected. However, the incidence increased notably with longer exposure: 10 out

of 38 (26.3%) neonates receiving phototherapy for 24–48 hours developed hypocalcemia. The highest

rate was observed in those treated for more than 48 hours, where 4 out of 8 (50%) developed

hypocalcemia.

Discussion

In the present study, 82% of the participants had normal serum calcium levels, while 18% demonstrated

hypocalcemia (<8 mg/dL). This prevalence is in agreement with findings reported by Sharma et al. [15],

who observed hypocalcemia in approximately 20–25% of the general adult population. Similarly, Khan et

al. [4] documented a prevalence of 17.4%, which closely parallels our observation of 18%. These

comparable rates suggest that mild hypocalcemia remains relatively common even among stable, non-

hospitalized populations.

However, the proportion of hypocalcemia observed in our study is considerably lower than that reported

in critically ill or hospitalized cohorts. Patel et al. [16] reported hypocalcemia in 55% of ICU patients,

attributing the high prevalence to systemic inflammation, organ dysfunction, and disrupted calcium

homeostasis in severe illness. Likewise, Gupta et al. [17] documented hypocalcemia in 48% of

postoperative patients, likely related to surgical stress, hemodilution, transient hypoparathyroidism, and

hormonal alterations following surgery. These contrasts highlight that our study population represents a

comparatively healthier and more stable cohort.

International data also demonstrate wide variation in calcium status across populations. A community-

based survey by Jones et al. [18] in the United Kingdom reported a lower prevalence of hypocalcemia

(12%) among adults, possibly reflecting better dietary calcium intake, routine vitamin D fortification, and

greater health awareness. In contrast, studies from South and Southeast Asia have reported substantially

higher rates, ranging from 25% to 40%, often associated with inadequate dietary calcium intake, limited

sunlight exposure, and a high prevalence of vitamin D deficiency, as described by Homayrani et al. [8]

and Kumar et al. [9].

The moderate hypocalcemia rate observed in our study may be influenced by multiple factors, including

sunlight exposure, dietary habits, vitamin D status, and underlying medical conditions—variables not

directly assessed in the present analysis but well documented in prior research by Reddy and Krishnappa

[11] and Kumar et al. [13]. Additionally, methodological differences such as laboratory assay techniques,

calibration standards, and the calcium cutoff values used may contribute to inter-study variability. These

findings underscore the importance of routine biochemical monitoring of calcium levels, particularly in

individuals at risk of nutritional deficiency or chronic illness. Even mild hypocalcemia has been

Balan S et al | DOI: 10.65188/nurexus.1054

Page 27

associated with neuromuscular symptoms, reduced bone mineral density, and impaired quality of life, as

highlighted in earlier studies by Rozario et al. [10] and Javaid et al. [12]. Future studies incorporating

dietary calcium intake, vitamin D levels, and parathyroid hormone measurements may provide deeper

insight into the determinants of calcium imbalance in this population.

Conclusion

In this study of 100 newborns receiving phototherapy for neonatal jaundice, 18% developed

hypocalcemia, highlighting that phototherapy can significantly reduce serum calcium levels. The

decrease in both total and ionized calcium after phototherapy was statistically significant, with longer

durations of phototherapy associated with a higher risk of hypocalcemia. Term neonates were less

affected compared to late preterm neonates. These findings underscore the importance of monitoring

serum calcium during phototherapy, particularly in neonates with extended treatment durations or

those born preterm. Early detection and timely intervention can prevent potential complications such

as neuromuscular irritability, seizures, and cardiac disturbances, thereby improving neonatal

outcomes.

Conflict of interest: Nil

Source Of Fund: Nil

Reference

1. Goyal S, Srivastava A, Bhattacharjee P, Goyal I, Malhotra K. Effect of phototherapy on serum calcium

levels in neonates receiving phototherapy for neonatal jaundice. Int J Res Med Sci. 2018;6(9):3124–8

2. Nepal Medical College Teaching Hospital study team. Hypocalcemia in jaundiced neonates receiving

phototherapy. Nepal Med Coll J. 2021;23(3):221–5. PubMed

3. Ali F, Abo-elela MG, Shehata ALM. Effect of phototherapy on serum level of calcium in infants with

hyperbilirubinemia: an interventional single-arm study. J Curr Med Res Pract. 2023;8(3):143–7.

4. Khan IA, Alam I, Khan I, et al. Effect of head covering on phototherapy induced hypocalcemia in term

neonates with hyperbilirubinemia: a randomized controlled study. J Neonatal-Perinatal Med.

2022;15(2):157–63.

5. Balamkar R, Sajjan A, Byakod S, Kalyanshettar SS. Effect of phototherapy on serum calcium levels in

neonates receiving double surface LED phototherapy for neonatal jaundice. Int J Paediatr Geriatr.

2021;4(1):59–61.

6. Study by melatonin and calcium measurement during phototherapy. Pediatr Res. 2021;89(4):882–6.

7. Electrolyte changes following phototherapy in neonatal hyperbilirubinemia: a prospective observational

study. Exp J Hosp Med. 2021;85(1):3402–6.

8. Homayrani E, et al. Prevalence of hypocalcemia after phototherapy in full-term newborns at Bandar Abbas

Hospital, 2013. Electron Physician. 2013;5(6):1312–1316.

9. Kumar A. Effect of phototherapy on serum calcium levels in full-term neonates with neonatal jaundice. Int

J Med Biomed Stud. 2020;4(2):1449.

10. Rozario CI, Pillai P, Ranamol T. Effect of phototherapy on serum calcium level in term newborns. Int J

Contemp Pediatr. 2017;4(2):442–6.

11. Reddy V, Krishnappa J. A prospective hospital-based observational study on electrolyte changes following

phototherapy in neonatal hyperbilirubinemia. J Neonatal Surg. 2024;13(1):9002.

Balan S et al | DOI: 10.65188/nurexus.1054

Page 28

12. Javaid QA, Aziz S, Noor-ul-Ain, Abid U, Afzal A, Javaid U. Effects of phototherapy on serum calcium

level in neonates with hyperbilirubinemia. J Rawalpindi Med Coll. 2023;27(2):2052.

13. Kumar MK, Srivastava S, Kumar R, Sachdeva M. Effects of phototherapy on neonatal electrolytes in

hyperbilirubinemia. Glob J Med Public Health. 2024;13(1):3900.

14. Patel P, et al. Effect of duration of phototherapy on serum calcium level in newborns with neonatal

jaundice. Pediatr Rev Int J Pediatr Res. 2022;9(3):17-22.

15. Sharma R, Gupta A, Malhotra S. Hypocalcemia prevalence among general adult population — cross

sectional analysis. Indian J Clin Biochem. 2021;36(4):420–5.

16. Patel V, Singh S, Das P. Serum calcium disturbances in critically ill patients: a retrospective analysis. Int J

Crit Illn Sci. 2023;13(1):45–50.

17. Gupta D, Verma R, Sharma N. Postoperative hypocalcemia: incidence and clinical significance. Surg

Today. 2022;52(8):1012–8.

18. Jones A, Smith B, Clark C. Community calcium status and nutrition survey in United Kingdom adults.

BMC Public Health. 2020;20:1123.