A 10-year-old (weight 25 kg, BSA 1.4 m2) receives a diagnosis of adrenal insufficiency. Which is the most appropriate initial treatment?
a. Desmopressin 0.05 mg orally twice daily.
b. Hydrocortisone 4 mg orally every 8 hours plus fludrocortisone 0.05 mg orally once daily.
c. Fluid replacement of more than 1400 mL/day.
d. Sapropterin 120 mg orally once daily.