Evaluation of the Relationship Between Congenital Hypothyroidism and Retinopathy of Prematurity in Very Low Birth Weight Newborns

Objective: Retinopathy of prematurity (ROP) is a vasoproliferative disease that mainly occurs in retinas of premature infants, and causes blindness in childhood. The aim of this study was to evaluate the risk factors for PR and the effect of congenital hypothyroidism (CH) on PR in very low birth weight infants (VLBW) (birth weight <1500 g). Material and Method: The retrospective study was conducted by the evaluation of medical records of hospitalized VLBW infants during the 51 months of follow-up. Patients were divided into groups according to diagnosed CH, and according to ROP requiring laser photocoagulation therapy. Results: There were 570 patients of 621 patients of whom we were able to obtain TFT results on the 5th day of the study. A total of 534 patients who survived the postnatal 1st month, and on whom we were able to perform both TFT and ROP examinations were included in the study. The PR rate was 26.1%(n=6) in the group with congenital hypothyroidism (n=23) and the ROP rate was 10.9%(n=56) in the non-CH group (n=511). However, there was no statistically significant difference between the groups in terms of ROP (p=0.077). The risk factors for premature retinopathy were mainly including low gestational age/birth weight, low 1st and 5th minute Apgar score, longer duration of mechanical ventilation and oxygen support, respiratory distress syndrome, intraventricular hemorrhage, bronchopulmonary dysplasia, hemodynamically significant patent ductus arteriosus and late neonatalsepsis. In infants with ROP, the levels of free thyroxine (sT4) were lower and the levels of thyroid stimulating hormone (TSH) were higher (p=0.002, 0.047, respectively). Conclusion: CH had no effect on ROP. However, other risks of prematurity on ROP were found to be more effective. In infants with ROP, sT4 was lower and TSH was higher. Since thyroid hormones have an effect on angiogenesis, further studies on the relation between ROP and thyroid hormones are warranted