The effect of thyroid functions on osteopenia of prematurity in preterm infants.

Background It is known that thyroid hormones have effects on bone development. In particular, the effect of thyroid hormones on osteopenia of prematurity (OOP) has not been examined in preterm infants. Our study aimed to examine the relationship between OOP and congenital hypothyroidism (CH) in preterm infants. Methods Very low birth weight infants (VLBW, <1500 g) were included in the study. Thyroid-stimulating hormone (TSH) and free thyroxine (fT4) levels were measured on postnatal day 5. Serum calcium, phosphorus and alkaline phosphatase (ALP) levels were studied as standard screening parameters for OOP at postnatal week 4. Patients with serum ALP level >700 IU/L were included in the OOP group. We intended to figure out the relationship between OOP and CH in infants. Results In our study, OOP frequency was 14.9% among 543 VLBW infants. There was no statistically significant difference between groups with and without CH (21.7% and 14.8%, respectively) in terms of OOP (p=0.632). Gestational age (GA) was significantly lower in infants with diagnosed OOP (p<0.001, p<0.001, respectively). In addition, the prevalence rates of mothers with preeclampsia, small for gestational age (SGA), respiratory support requirement, late-onset neonatal sepsis (LOS), bronchopulmonary dysplasia (BPD) and full enteral feeding time were found to be higher in the OOP group (p<0.05). Conclusions We found that thyroid hormones had no effect on OOP in preterm infants. Therefore, future randomized controlled studies as well as long-term outcome studies are warranted on this topic.