Table 1.

Factors investigated

	Baseline	6 mo	12 mo	18 mo	24 mo	36 mo
QCT*	✓		✓		✓	✓
DXA	✓		✓		✓	✓
Bone age (from hand or wrist)	✓a				✓b
Blood for:
Bone-specific alkaline phosphatase	✓	✓	✓		✓	✓
Intact parathyroid hormone	✓
Osteocalcin	✓	✓	✓		✓	✓
Hemoglobin and hematocrit	✓	✓	✓	✓	✓	✓
25-hydroxyvitamin D	✓
Calcium and albumin	✓	✓	✓	✓	✓	✓
Phosphorus	✓		✓		✓	✓
Testosterone or estradiol	✓		✓		✓	✓
Liver function enzymes	✓		✓		✓	✓
Blood urea nitrogen and creatinine	✓		✓		✓	✓
Free T4, T4, thyroid stimulating hormone	✓				✓
Ferritin	✓		✓		✓	✓
β human chorionic gonadotropin	✓		✓		✓	✓
3A4 receptor genotyping	✓
Urine for:
Sodium	✓	✓	✓	✓	✓	✓
Calcium:creatinine ratio	✓	✓	✓	✓	✓	✓
N-telopeptide	✓	✓	✓		✓	✓
Height and weight	✓	✓	✓	✓	✓	✓
Tanner stage	✓		✓		✓	✓
Dietary intake:
Magnesium	✓		✓		✓	✓
Potassium	✓		✓		✓	✓
Calcium	✓		✓		✓	✓
Protein	✓		✓		✓	✓
Phosphorus	✓		✓		✓	✓

Mo=months

QCT=quantitative computed tomography

DXA=dual-energy x-ray absorptiometry

^aBone age will not be done on patients older than 25 years.

^bBone age will be obtained at 24 months only if the patient is skeletally immature at enrollment.

^*QCT-determined BMD serves as an eligibility screen for participation in the interventional phase (Study 2)