At the time of admission, her body weight, head circumference, and length were 4.11 kg (<3rd percentile), 37 cm (<3rd percentile), and 57 cm (20th percentile), respectively. Physical examination revealed coalescing erythematous plaques with overlying desquamation covering the buttocks and genitourinary region (Figure), with smaller erythematous plaques dispersed diffusely across her anterior torso, arms, hands, and chin. Her face and extremities were markedly edematous. Nails and mucous membranes were normal, and she had no evidence of hepatomegaly or alopecia. Abnormal laboratory values included the following: hemoglobin, 7.6 g/dL (reference range, 10.0-18.0 g/dL); hematocrit, 24.2% (reference range, 31.0%-55.0%); total protein, 3.0 g/dL (reference range, 6.0-8.3 g/dL); albumin, 1.2 g/dL (reference range, 3.5-5.7 g/dL); prealbumin, <7.0 mg/dL (reference range, 18-45 mg/dL); aspartate aminotransferase, 49 U/L (reference range, 13-39 U/L); and increased fecal fat. Her zinc status was not determined until several days after treatment initiation and was 43.6 μg/dL (reference range, 67.0-124.0 μg/dL). The white blood cell count (14 600/μL [reference range, 5000-19 500/μL]), alanine aminotransferase (43 U/L [reference range, 7-52 U/L]), alkaline phosphatase (355 U/L [reference range, 120-450 U/L]), and total bilirubin (0.4 mg/dL [reference range, 0.3-1.2 mg/dL]) were within normal limits. A sweat chloride test was unsuccessful, but a CF polymerase chain reaction test was positive for the homozygous ΔF508 mutation, confirming the diagnosis of CF. (To convert alanine aminotransferase, alkaline phosphatase, and aspartate aminotransferase to microkatals per liter, multiply by 0.0167; albumin, hemoglobin, and total protein to grams per liter, multiply by 10; total bilirubin to micromoles per liter, multiply by 17.104; hematocrit to a proportion of 1.0, multiply by 0.01; prealbumin to milligrams per liter, multiply by 10; white blood cell count to ×109 per liter, multiply by 0.001; and zinc to micromoles per liter, multiply by 0.153).