Influence of corticosteroids and prematurity on bone density in preterm neonates

Corticosteroids are frequently used in NICU's to extubate ventilated children
who are difficult to wean. Dexamethasone has different (long term) effects on
bloodpressure, glucose metabolism, growth and braindevelopment. It also seems
to have an effect on bone formation. A previous study invatigating the
influence of antenatal corticoids on calcium metabolism and the correlation
between biochemical parameters in blood and urine and bone density, as measured
bij speed of sound (SOS), showed a temporary diminished bone density in preterm
infants. Hydrocortisone might have less side effects than dexamethasone.
There are other factors (intrauterine growth retardation, chronic lung disease
and long term hospitalization) that may influence bone development. Comparison
of preterm neonates with and without the use of corticoids, with abberant
ricketsscreening and healthy preterm neonates would give more insight in the
cause of temporary diminished bone density.

To prove that 1 corticosteroids administration is the main factor in diminished
bone density of preterm neonates, 2 dexamethasone has more influence than
hydrocortisone and 3 children with abberant ricketsscreening have a transient
diminished bone density as compared to the normal premature population.

Prospective cohort study

SOS measurements by Sunlight Omnisense bone sonometer, is a non-invasive
methode without radiation. An ultrasound wave is transmitted axial through the
bone and read by a probe. The attenuation (in dB/MHz) and the speed (SOS, in
m/s) is measured.
Measurements of SOS at the midpoint between the apex of the medial maleolus and
the distal patellar apex as a measure for bone density at the day af birth and
after 1, 3, 6 and 9 weeks. If corticosteroids are used measurements before the
first and after the last gift will be performed as well.