Establishing reference intervals for electrolytes in newborns and infants using direct ISE analyzer.

BACKGROUND: To generate clinically applicable reference intervals (RIs) for commonly requested electrolytes in Ethiopian newborns and infants that can help in early detection, close monitoring and correction of electrolyte abnormalities. Cord blood (from newborns, n = 60) and venous blood samples (from infants, n = 57) were collected and analyzed using direct ISE analyzer, AVL (9181). MedCalc® software was applied to determine the robust upper and lower end points covering 95% of the reference values of each electrolyte with respective 90% CIs. FINDINGS: This is an extension report of our recent study; and hence is resulted from the same data source. The level of Na+ and K+ showed difference in newborns and infants even though combined RIs were suggested by the Haris and Boyd rule as 126-143 mmol/l and 4.0-7.9 mmol/l respectively. However, Cl- values failed to show such a difference and thus a combined RI was determined to be 100-111 mmol/l. Almost all maternal, neonatal and infantile factors were not able to affect the values of the electrolytes. CONCLUSION: Combined RIs are suggested for the interpretation of electrolyte values in newborns and infants without taking the effect of maternal, neonatal and infantile factors into account. Since the RIs were different from previously reported values, it will be appropriate to apply such RIs for the interpretation of electrolyte values in Ethiopian pediatric population.

Is the difference in neonatal blood glucose concentration of caesarian and vaginally delivered term infants requiring separated reference intervals?

BACKGROUND: Mode of delivery has been reported to affect the cord blood glucose level of newborns. Vaginally delivered (VD) newborns were found to have relatively increased concentration of cord blood glucose than those delivered by cesarean section (CS). The aim of this study is thus to determine whether the difference in cord blood glucose concentration among VD and CS newborns is necessitating partitioned reference intervals (RIs) for the laboratory diagnosis of neonatal hypoglycemia. METHODS: A total of 60 newborns were included from Tikur Anbessa Specialized Hospital (TASH). Cord blood samples were collected and analyzed for glucose by Glucose-oxidase (GOD-PAP) method in TASH laboratory using HumaStar 300 from November 2010 to April 2011. All pre-analytical, analytical and post-analytical aspects were thoroughly controlled. A robust method was used for the determination of reference intervals using MedCalc® software Version 11.6.1. RESULTS: VD newborns accounted for 71.7% (n = 43) while the CS newborns accounted for 28.3% (n = 17). No statistically significant difference was noted in the studied demographic variables among VD and CS newborns except for blood glucose level. The RIs were then determined to be 2.46-6.85 mmol/l and 2.46-5.04 mmol/l for VD and CS newborns respectively. The combined RI was 2.24-6.48 mmol/l. CONCLUSION: Combined RI better be used for the interpretation of cord blood glucose values in VD and CS newborns. Cord blood glucose concentrations of 2.24 mmol/l can be used as statistical estimates of cut off points for neonatal hypoglycemia in newborns irrespective of their mode of deliveries.

Robust reference intervals for liver function test (LFT) analytes in newborns and infants.

BACKGROUND: Reference intervals (RIs) are ranges of upper and lower limits of a given analyte which are used for a laboratory test to determine whether a disease is present or absent or to know if the patient is at risk for future disease states. In Ethiopia, a country with highly diversified population groups and geographical sites, there are no established RIs to metabolic analytes including the liver function test (LFT) analytes for the pediatric population though it has been known that liver function assessment in this population is vital as a result of varied vulnerability to both endogenous and xenobiotic substances. METHODS: A cross sectional study was conducted in Tikur Anbessa Specialized Hospital (TASH) and Teklehaymanot Health Center (THC) from November 2010 to April 2011. 117 cord blood (from newborns) and venous blood samples (from infants) were collected and analyzed using HumaStar 300. All pre-analytical, analytical and post-analytical aspects were thoroughly controlled. A robust, CLSI/ IFCC recommended, method was used for the determination of upper and lower end points covering 95% of the reference values of each analyte with respective 90% CIs using MedCalc® software. RESULTS: Combined RIs for newborns and infants were established for albumin, AST, ALP, direct bilirubin and total bilirubin to be 3.88-5.82 g/dl, 16.1-55.4U/l, 130-831U/l, <0.41 mg/dl and <1.37 mg/dl respectively. But, separated RIs were indicated for ALT and GGT as 1.2-23.1U/l and 6.94-24.8U/l ALT; and 30.6-160.7U/L and 10-28.2U/l GGT for newborns and infants respectively. Some maternal and infantile factors were identified to affect the values of analytes. CONCLUSION: Almost all analytes were different from previously reported values for other target population of similar age group, kit insert values and adult values. So, interpretation of values of these analytes in newborns and infants of Ethiopian population sounds better to be performed by using such RIs taking the effect of some maternal and infantile factors in to account.