Pediatric emergency medicine trisk 608

TABLE 95.4 INITIAL LABORATORY STUDIES a Test Blood CBC (plasma) Laboratory abnormality Indications, comments metabolic diseases a Neutropenia (± vacuoles), anemia, and/or thrombocytopenia Organic acidemias Urea cycle defects Carbohydrate intolerance disorders Carbohydrate production/utilization disorders Lysosomal storage disorders Mitochondrial disorders Glucose (serum) Hypoglycemia Aminoacidopathies Organic acidemias Fatty acid oxidation defects Carbohydrate intolerance disorders Carbohydrate production/utilization disorders Mitochondrial disorders Test of acid–base Primary metabolic status (serum) acidosis Electrolytes Aminoacidopathies Anion gap Organic acidemias pH (arterial or Fatty acid oxidation venous) defects Carbohydrate intolerance disorders Carbohydrate production/utilization disorders Mitochondrial disorders Primary respiratory alkalosis Urea cycle defects Ammonia (plasma) Hyperammonemia Aminoacidopathies Organic acidemias Urea cycle defects Neutropenia may be masked by infection Patients with certain IEMs are at increased risk of infection; infection can also precipitate metabolic crisis Anemia hemolytic, megaloblastic, or normocytic, depending on specific IEM Hypoglycemia may be due to primary defect of gluconeogenesis or glucose consumption that exceeds production Na+ , K+ , Cl− usually normal unless abnormal secondary to vomiting, which may produce hyperchloremic metabolic acidosis, or to rhabdomyolysis, which may result in hyperkalemia Normal bicarbonate does not rule out amino or organic acidemias Obtain if altered consciousness, persistent or recurrent unexplained vomiting, recurrent dizziness or ataxia, primary metabolic acidosis with increased anion gap, Fatty acid oxidation defects primary respiratory alkalosis in the absence of toxic ingestion Must be free-flow venous (no tourniquet) or arterial Arterial preferred because skeletal muscle releases ammonia, ice sample immediately, assay promptly Newborns 90–150 μg/dL, children 40–120 μg/dL, adults 18–54 μg/dL (www.pediatriccareonline.org/pco/ub/view/Pediatricdrug-Lookup/153930/0/Normal-Laboratory-Valuesfor-Children ) Normal