Background Phototherapy can decrease total serum bilirubin (TSB) but the duration of phototherapy remains unclear. Phototherapy at Dr Kariadi hospital is usually done for 12–24 hours irrespective of initial TSB.

Objective To determine the mean difference of the decrease of TSB at 6 hrs, 12 hrs, 18 hrs or 24 hrs.

Methods A quasi experimental study was done in 40 hyperbilirubinemia neonates, divided into 4 groups (group I: total bilirubin 13–15 mg/dL, phototherapy 6 hrs; group II: 16–17 mg/dL, phototherapy 12 hrs; group III: 18–20 mg/dL, phototherapy 18 hrs and group IV: >20 mg/dL, phototherapy 24 hrs), using 4 special blue fluorescent tubes (Philips TL52/20W), with a 50 cm distance. Hemolytic condition and breast feeding were confounding factors which can influence the effectiveness of phototherapy. Wilcoxon signed ranks test was used to analyze the mean difference of decrease TSB to duration of phototherapy.

Results There was no significant mean difference of TSB decrease in group II and III (p>0.05), conversely there was a significant mean difference of TSB decrease in group IV (p<0.05). After the first six hours the biggest average of total bilirubin decrease was found in group IV (4.83±2.42 mg/dL). After the last phototherapy, the TSB decrease in group I, II, III and IV were 3.14±1.86 mg/dL, 4.89±1.82 mg/dL, 7.96±1.94 mg/dL, and 13.41±3.27 mg/dL. There was no significant difference of TSB after phototherapy among groups according to the hemolytic condition or breast feeding.

Conclusions The only significant mean difference of TSB decrease was in group IV.