Problem. The nurse reports an infant has a blood glucose level of 240 mg/dL. Hyperglycemia is defined as a whole blood glucose level >120–125 mg/dL or a plasma glucose concentration >145–150 mg/dL regardless of gestational or postnatal age or weight. One review also suggests that a blood glucose of ≥216 mg/dL in extremely low birthweight (ELBW) infants as a definition of neonatal hyperglycemia due to the risk of osmotic diuresis. There is an association between hyperglycemia and increased morbidity and mortality.
What is the serum glucose value on laboratory testing? Dextrostix values are often inaccurate because the procedure is performed incorrectly or the strips are old and no longer reliable. Chemstrip-bG values are thought to be more reliable by some, but it is best to obtain a serum glucose level from the laboratory before initiating treatment.
Is glucose being spilled in the urine? A trace amount of glucose in the urine is accepted as normal. If the urinary glucose level is +1, +2, or greater, the renal threshold has been reached with an increased chance of osmotic diuresis. Some institutions accept a urinary glucose level of +1 without treating the patient (controversial). Others feel that the presence of >1% of glucosuria suggests osmolar changes and will treat. Note: Each 18-mg/dL rise in blood glucose causes an increase in serum osmolarity of 1 mOsm/L. Normal osmolarity is 280–300 mOsm/L.
How much glucose is the patient receiving? Normal initial maintenance glucose therapy in infants not being fed orally is 5–7 mg/kg/min (see Chapter 8).
Are there signs of sepsis? Sepsis may cause hyperglycemia by inducing a stress response (catecholamine mediated).
What is the birthweight of the infant? Low birthweight is the most significant risk factor for hyperglycemia at any gestational age. The incidence is ~2% in infants >2000 g, 45% in infants <1000 g, and 80% in infants <750 g.
Does the infant have any of the high-risk factors for hyperglycemia? Risk factors include gestational age <37 weeks, postnatal age <72 h, weight <2500 g, hypoxia, and infection. These infants should have frequent monitoring of their blood sugars.
Differential diagnosis. Hyperglycemia is very common in ELBW premature infants (60–80%) and is associated with increases in mortality, intracranial hemorrhage, stage II/III NEC, risk of sepsis (if hyperglycemia occurs in the first few days after birth), ROP (in ELBW infants), and developmental delay. Etiologies include excess administration or production, inadequate insulin secretion or insulin resistance, glucose intolerance, and defective glucoregulatory hormone control. The main concern with hyperglycemia is it can cause hyperosmolarity, osmotic diuresis, and subsequent dehydration and is associated with intraventricular hemorrhage.
Excess glucose administration has a major role in hyperglycemia. Incorrect calculation of glucose levels or errors in the formulation of intravenous (IV) fluids may cause hyperglycemia.
Inability to metabolize glucose may occur with prematurity or secondary to sepsis or stress. Most commonly, a tiny infant on total parenteral nutrition becomes hyperglycemic because of glucose intolerance.
Extremely low birth weight infants (<1000 g) have greater fluid requirements because of their immature renal function and increased insensible water loss. This often leads to a high volume of fluid and administering too much glucose. They also may ...
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