Objective:To study the correlation between transcutaneous bilirubin (TcB) level measured from shielded skin and total serum bilirubin (TSB) level after phototherapy in premature infants.Methods:From July 2019 to July 2021,preterm infants with jaundice admitted to the Department of Neonatology of our hospital and received phototherapy were prospectively enrolled in the study. The infants were assigned into 26~31w group, 32~34w group and 35~36w group according to their gestational ages. During phototherapy, the forehead, the chest and the perineum were shielded. TcBs were measured at the above mentioned areas three times each before and after phototherapy and TSB was measured from venous blood samples.Results:A total of 306 premature infants were included, with 51 cases in 26~31w group, 126 cases in 32~34w group and 129 cases in 35~36w group. Before phototherapy, TcBs of the forehead, the chest and the perineum of all infants were correlated with TSB ( r=0.699, 0.913, 0.734, P<0.001) with TcB of the chest showed the best correlation. A linear regression equation was established using the TSB before phototherapy and the TcB of the chest: TSB=0.634+0.912TcB. After phototherapy, TcBs of the forehead, the chest and the perineum of all infants were also correlated with TSB ( r=0.586, 0.879, 0.690, P<0.001) with TcB of the chest showed the best correlation and the linear regression equation was TSB=1.910+0.736TcB. Conclusions:For preterm infants with gestational age of 26~36w, TcB of the shielded chest skin after phototherapy is correlated with TSB and a linear regression model can be established.

Mycoplasma pneumonia(MP)is a common cause of respiratory tract infections in children. The symptoms of MP infection range from mild to severe,which is often self-limiting.A few cases can develop to severe extrapulmonary complications.Because the symptoms and imagings of MP infection are not specific,so it may by means of diagnostic tests such as serology or PCR to guide the accurate therapy and to reduce the oc-currence of drug-resistance.In addition,recent studies indicate that MP can be carriage in the upper respiratory tract among healthy children,but clinically it is discriminate between MP infection and carriage.The asympto-matic carriage of MP could be the results of recent infection or the pathogenic persistence after infections.