Flashcards in Glucose Metabolism Deck (70)
What infants are at increased risk for hypoglycemia secondary to abnormal endocrine function?
LGA, infants born to IDM, erythroblastosis fetalis
Fetal glucose levels are what percentage of maternal values?
How does hyperinsulinemia occur in the infant of a IDM MOB?
the fetal pancreas will secrete insulin in response to glucose load and secretes levels appropriate to that environment. After delivery, with maternal glucose supply gone, the baby's pancreas may not be able to back off for hours or days, creating a hypoglycemic environment
What is erythroblastosis fetalis?
dz of hemolysis, the enzyme glutathione reductase is a by product of that hemolysis and it inactivates circulating insulin. As is inactivates insulin, it stimulates the pancreas to produce even more
What infants are at increased risk for hypoglycemia secondary to increased glucose utilization?
babes that are stressed or sick, with increased energy needs and may rapidly deplete their glycogen stores; perinatal asphyxia, hypothermia, neonatal sepsis and polycythemia/ hyperviscosity
What are some iatrogenic causes of hypoglycemia?
use of maternal drugs, erroneous placement of umbilical lines and administration of IV glucose to the mother during labor
What maternal drugs are known to contribute to neonatal hypoglycemia?
tocolytics, terbutaline, ratidine, propanolo and oral hyperglycemic agents; cause MOB to become hyperglycemia and the baby will over secrete insulin
What are the landmarks for umbilical line placement?
high lines: T6-T9; low lines: L3-4
How does erroneous line placement contribute to hypoglycemia in the neonate?
if UAC is T11-12, this is about the location that the celiac artery is connected to the aorta. If the UAC is there then is infusing dextrose, it may be close enough to this artery that it directly stimulates the pancreas to secrete even more insulin
How should hypoglycemia secondary to umbilical line placement be treated?
pull line into low lying position and within hours, hypoglycemia should be resolved
Why are so many symptoms of hypoglycemia neurological?
since the brain needs glucose to fx, many manifestations of hypoglycemia are neurological in origin
What are symptoms of hypoglycemia?
jitteriness/tremors, cyanosis, overt sz, apnea/irregular breathing, irritability/lethargy, hypothermia, weak and/or high pitched cry, poor feeding, eye rolling, sweating, cardiac failure, hypotonia, respiratory distress and pallor
What pathologic states include hypoglycemia in its presentation?
sepsis, asphyxia, hypocalcemia, CNS lesions, CHD, polycythemia/hyperviscosity and metabolic abnormalities
If a baby can be fed enterally, how should hypoglycemia be treated?
feed them, reassess glucose 15-30 min after the intervention
If a baby cannot be fed enterally, how should hypoglycemia be treated?
D10 bolus 2-4cc/kg given over 1mL/min (minimum infusion rate) followed by continuous IVF
What is the GIR of D10W at TF 80cc/kg/d?
What course of action should be taken if hypoglycemia persists after intervention?
increase GIR either by increasing the rate of infusion or the concentration of glucose in the IVF; monitor line position, insert central lines if D>12.5%, monitor insulin levels
Why might insulin levels need to be drawn in an infant born to IDM MOB?
to document levels of hyperinsulinemia
What is the effect of insulin on an infant's respiratory function?
insulin tends to decrease surfactant production and quality and increase their cumulative risk for RDS (even if later GA)
What is insulin?
a hormone that enables glucose to enter the cell by ∆ cell wall permeability ; the major blood glucose reducing hormone
How does insulin levels affect brain utilization of glucose?
cerebral glucose utilization is NOT dependent on insulin
When does insulin first appear in the fetus?
by 12wk GA
How does hyper insulin affect growth?
insulin should work in synergy with growth hormone and is vital for growth. when the fetus has excessive insulin, then glucose, protein and fat synthesis is accelerated, leading to macrosomia
What is the maximal glucose oxidative capacity and when is it exceeded?
do not want to exceed 16-18mg/kg/min; occurs when excess glucose is converted to fat leading to increased O2 consumption and increased CO2 production
When should adjunct therapies be considered for the treatment of refractory hypoglycemia?
not until GIR is > 12mg/kg/min with no ∆ in glucose levels
What is glucagon and how is it helpful in treating refractory hypoglycemia?
an agent that releases glycogen from hepatic stores. its helpful when the newborn has adequate stores and hyper insulin levels. It allow for a RAPID, TRANSIENT increase in glucose concentration- may be helpful in babe that IV access is difficult
How is GIR calculated?
(%D x IVF rate)/ (6x wt in kg)
At what levels is an infant considered hyperglycemic?
term infant >125mg/dL; preterm infant > 150mg/dL
What are causes of hyperglycemia in the neonate?
inability to metabolize glucose, excess administration, medications, hyperosmolar formula, neonatal diabetes, sepsis, stress response (ex: asphyxia)