Hypoglycemia (blood glucose [BG], <2.6 mmol/L) is common in neonates during the first week of life.1 Although this may be physiologically normal, hypoglycemia can be pathological leading to neurological impairment.2 All infants therefore considered at risk for hypoglycemia undergo BG monitoring after birth. However, identifying those actually at risk from low BG levels due to impaired counter regulation is challenging.1,3 Medical interventions need to balance the risks from hypoglycemia with the potential harm from medical interventions and the need to separate mother and baby.2 Development of point-of-care (POC) technology that measures alternative fuels (ketones and lactate) could provide the means to identify those infants at significant risk,2 while avoiding unnecessary separation.
The aims of this study were to validate the accuracy of the Nova Biomedical POC ketone meter and lactate meter in newborn babies considered at risk for hypoglycemia and to provide pilot data to support a study to investigate the role of these devices as part of standard clinical care.
A prospective validation study at the Rosie Hospital, Cambridge, UK was performed. Infants were eligible if they were clinically stable and having BG levels taken for clinical screening. Informed consent was sought from parents. Blood samples were taken prefeeds for glucose, ketones, and lactate measurement at the cot side using the Nova StatStrip POC meter, with paired samples collected for laboratory comparison. The latter was immediately spun, separated and frozen at −20°C before being batch analyzed using criterion standard techniques (Siemens Dimension analyzer).
Sixty infants at risk of hypoglycemia were recruited to the study. The reason for study recruitment included maternal diabetes (n = 22), small for gestational age (n = 6), or due to preterm labor, maternal β-blocker use, hypoglycemia, or suspected sepsis (n = 32). Fifty-nine BG values were obtained by POC measurement (mean [SD], 2.91 [0.92] mmol/L). Twenty samples were obtained when the BG was less than 2.6 mmol/L. All of the infants were clinically well and asymptomatic for hypoglycemia. Fourteen paired samples were obtained when infants were hypoglycemic. The ketone levels measured by POC and in the laboratory were low (Fig. 1) and did not appear to be related to the BG level (correlation coefficient laboratory, 0.192). Bland-Altman plot showed a variable pattern of results between the POC lactate and the reference method. Potential preanalytical causes are under investigation (Fig. 2). Lactate levels initially appeared higher in hypoglycemic babies; however, this was not statistically significant and warrants further investigation (Fig. 3).4
The low levels of ketones in this population make validation of POC meters difficult, and the lack of a relationship to the BG raises questions regarding the clinical importance of ketogenesis as a cerebral fuel in these patients. The relation between hypoglycemia and raised lactate also requires further investigation.
1. Cornblath M, Hawdon JM, Williams AF, et al. Controversies regarding definition of neonatal hypoglycemia
: suggested operational thresholds. Pediatr
2. Hay WW Jr, Raju TN, Higgins RD, et al. Knowledge gaps and research needs for understanding and treating neonatal hypoglycemia
: workshop report from Eunice Kennedy Shriver National Institute of Child Health and Human Development. J Pediatr
3. Hawdon JM, Ward Platt MP, Aynsley-Green A. Patterns of metabolic adaptation for preterm and term infants in the first neonatal week. Arch Dis Child
4. Harris DL, Weston PJ, Harding JE. Lactate
, rather than ketones, may provide alternative cerebral fuel in hypoglycaemic newborns. Arch Dis Child Fetal Neonatal Ed