A Study of the Relationship Between Cystatin C and Metabolic Bone Disease in Preterm Infants.

OBJECTIVE: Cystatin C (CysC) is commonly used as a marker of renal failure in premature infants. The aim of this study was to investigate serum CysC levels in osteopenia of prematurity (OP) and determine whether CysC could be safely used as a marker of renal insufficiency in infants with OP.

METHODS: Subjects were 50 preterm infants (≤32 gestational weeks). Calcium (Ca), phosphorus (P) and alkaline phosphatase (ALP) serum levels were measured in postnatal week nine, and bone density was measured concurrently by quantitative ultrasonography. Patients with a Z score of <-2 were considered to have OP.

RESULTS: The mean serum CysC levels in preterm infants in postnatal week nine were 1.50±0.19 mg/L. Serum CysC levels were not correlated with speed of sound values, Z scores, serum Ca, P or ALP levels. Serum CysC levels were not significantly different between infants with OP [1.50 (1.35-1.61) mg/L] and in infants without OP [1.58 (1.28-1.70) mg/L].

CONCLUSION: The presence of OP does not affect the safety of CysC as a marker of renal insufficiency in preterm infants.