SERUM CYSTATIN C LEVELS IN NEONATES AT BIRTH AND THREE DAYS OF LIFE DELIVERED AT LAGOS STATE UNIVERSITY TEACHING HOSPITAL, LAGOS: A MEASURE OF RENAL FUNCTION

Abstract

Background. Cystatin C is an endogenous marker used to estimate GFR. It offers significant
advantages over serum creatinine as an endogenous marker of renal function. Normal reference
values have been documented in neonates outside Africa but no study has been documented in
African neonates. With reports that race may affect serum Cystatin C values, this study was
carried out to document values in neonates in Nigeria.
Objectives. The objectives of the study were: to document values of serum Cystatin C in
apparently healthy term neonates at birth and three days of life and to estimate GFR in the
subjects using a Cystatin C equation.
Methods. This was a hospital based prospective study conducted between 10th of October and
31st of December 2014. Term neonates with normal Apgar scores at birth and who were
apparently healthy were recruited from consecutive deliveries. A total of 120 babies had serum
Cystatin C measured from the cord blood at birth and venous blood when they were three days
old using ELISA method. The data were analysed using Statistical Package for Social Sciences
version 20. Probability value (p-value) of ≤0.05 was accepted as statistically significant.
Results. The mean serum Cystatin C values for cord blood and third day venous samples were
1.67±0.52mg/L and 1.62±0.52mg/L, respectively, (p=0.87). The cord blood and third day serum
Cystatin C values for males were 1.67±0.47mg/L and 1.68±0.51mg/L, respectively (p=0.77). The
values of the cord blood and third day venous samples of serum Cystatin C for the females were
1.68±0.56mg/L and 1.58±0.52mg/L, respectively (p=0.22). The serum Cystatin C levels were
similar amongst the different birth weight groups and gestational age, (p > 0.05). The median and
mean estimated GFR based on cord blood and third day venous samples from the equation by
Filler and Lepage were 44.67 (56.80±27.64) and 51.29 (60.83±36.09)ml/min/1.73m2,
respectively. However, when the Zappitelli equation was applied, the median and mean GFR
estimated were 38.18 (48.32±22.29) and 43.82 (51.27±28.43)ml/min/1.73m2, respectively.
Conclusion. The cord blood and third day serum Cystatin C values were similar. Serum Cystatin
C values were independent of gender and birthweight of neonates. The values of serum Cystatin
C in Nigerian neonates were comparable to that reported for neonates in other regions of the
world. GFR estimates using the Zappitelli equation had values that were closely related to
reference GFR measured in neonates while the GFR estimates by the Filler and Lepage equation
had higher values.
It is recommended that ELISA technique may be used to measure serum Cystatin C levels in
neonates. In addition, when estimating GFR in neonates using the Cystatin C equations, the
Zappitelli equation is preferred to the equation by Filler and Lepage.

SERUM CYSTATIN C LEVELS IN NEONATES AT BIRTH AND THREE DAYS OF LIFE DELIVERED AT LAGOS STATE UNIVERSITY TEACHING HOSPITAL, LAGOS: A MEASURE OF RENAL FUNCTION