A 4-month-old child has poor weight gain. Her current weight is less than the 5th percentile, height about the 10th percentile, and head circumference at the 50th percentile. The planned pregnancy resulted in a normal, spontaneous, vaginal delivery; mother and child were dis- charged after a 48-hour hospitalization. Feeding is via breast and bot- tle; the quantity seems sufficient. The child has had no illness. The examination is unremarkable except for the child’s small size. Screening laboratory shows the hemoglobin and hematocrit are 11 mg/dL and 33%, respectively, with a platelet count of 198,000/mm3. Serum electrolyte levels are sodium 140, chloride 105, potassium 3.5, bicarbon- ate 17, blood urea nitrogen 15, and creatinine 0.3. Liver function tests are normal. Urinalysis reveals a pH of 8 with occasional epithelial cells but no white blood cells, bacteria, protein, ketones, or reducing substances. Which of the following is the most appropriate therapy for this child? A. Transfusion with packed red blood cells (PRBCs)
B. Intravenous (IV) infusion of potassium chloride
C. Sweat chloride analysis
D. Growth hormone determination
E. Oral supplementation with bicarbonate