Vitamin D Deficiency in Adolescent Girls

Mass General Brigham

Status

Completed

Conditions

Healthy

Vitamin D Deficiency

Treatments

Other: placebo pill

Dietary Supplement: ergocalciferol

Study type

Interventional

Funder types

Other

Identifiers

NCT01180946

2010-P-001126/1

Details and patient eligibility

About

Fibroblast growth factor 23 (FGF23) is a newly discovered hormone which regulates phosphate and vitamin D levels. In this study, we are looking at what the normal levels of FGF23 are in adolescent girls and how these levels vary with other hormonal measurements. We will also be looking at whether vitamin D supplementation in adolescents who are deficient in vitamin D alters the levels of FGF23 and other factors including insulin resistance.

Full description

Fibroblast growth factor 23 (FGF23) is a newly discovered hormone. Its primary function is to regulate phosphate metabolism, which it does both by directly regulating phosphate excretion through the kidney as well as by regulating vitamin D activity. What controls FGF23 levels is still under investigation; potential factors include dietary phosphate intake and vitamin D levels.

In this pilot study, we aim to investigate what the normal levels of FGF23 are in healthy girls and how these are related to other measurements of bone and mineral metabolism. Since vitamin D deficiency is very common in healthy girls, we expect a subset of the subjects in this study to be vitamin D deficient. We will then randomize these girls to vitamin D repletion or placebo and follow changes in FGF23 levels. Vitamin D deficiency has also been implicated in insulin resistance which is a precursor to diabetes. We will therefore also look at changes in insulin resistance with vitamin D repletion.

Enrollment

90 patients

Sex

Female

Ages

9 to 18 years old

Volunteers

Accepts Healthy Volunteers

Inclusion criteria

healthy girls aged 9-18 years

Exclusion criteria

significant cardiac, hepatic, oncologic, or psychiatric disease
a history of malabsorption, kidney stones, hypoparathyroidism, or growth hormone deficiency
pregnancy
diabetes mellitus
BMI>/= 99th percentile for age and sex
fracture within the preceding 3 months
hypogonadism (no pubertal development by age 12, absence of menarche by age 14)
serum calcium <8 mg/dl or >11 mg/dl
radiographic evidence of rickets
use of medications know to affect serum phosphate levels including phosphate-binding antacids, sodium etidronate, calcitonin, excessive doses of vitamin D (>1000 units per day), excessive doses of vitamin D (>20,000 units/day), calcitriol, growth hormone, or anti-convulsants.
use of hormonal birth control