Review Question - QID 109904

A 2-day-old boy is evaluated in the newborn nursery after the nurse witnessed the child convulsing. The child was born at 39 weeks gestation to a healthy 32-year-old G1P0 woman. Initial examination after birth was notable for a cleft palate. The child’s temperature is 99°F (37.2°C), blood pressure is 100/60 mmHg, pulse is 115/min, and respirations are 18/min. On exam, he appears somnolent. His face demonstrates periorbital fullness, hypoplastic nares, and small dysmorphic ears. A series of labs are drawn and shown below:

Hemoglobin: 13.1 g/dL
Hematocrit: 40%
Leukocyte count: 4,000/mm^3 with normal differential
Platelet count: 200,000/mm^3

Serum:
Na+: 140 mEq/L
Cl-: 100 mEq/L
K+: 3.8 mEq/L
HCO3-: 25 mEq/L
BUN: 19 mg/dL
Glucose: 110 mg/dL
Creatinine: 1.0 mg/dL
Ca2+: 7.9 mg/dL
Phosphate: 4.7 mg/dL

This patient is deficient in a hormone that has which of the following functions?