Growth Hormone and Endothelial Function in Children

Phase 4

Completed

Brief Summary: Objective: This study is designed to determine whether growth hormone treatment in children 8 to 18 years of age alters function of the lining of the arteries. This may play a role in increasing or decreasing the risk of heart disease.

Methods. Twenty children, for whom growth hormone therapy will be otherwise provided, will be studied before and 3 months after starting growth hormone. Subjects can be on other hormonal replacements but no other medications.

Each study will be done in the fasting state. The blood vessel function will be determined by measuring the change in forearm blood flow before and after blocking flow to the arm for 5 minutes. Blood will be drawn after the test to measure glucose, insulin and fats.

Detailed Description: The purpose of the research is to learn more about how the lining of arteries in the body (called the endothelium) is affected by growth hormone treatment in children and adolescents. Poor function by the blood vessels is associated with increased risk of heart disease or stroke. This research is being done because growth hormone treatment has been shown to make the endothelium work better in adults. Growth hormone treatment may have the same or different effects in children because the dose is larger in children.

Children between 8 and 18 years who are to be started on growth hormone will be eligible to participate. Blood vessel function will be studied before starting growth hormone and 3 months after. This will be done by measuring blood flow to the arm before and after 5 min of stopping blood flow to the arm. The three months of growth hormone will be given free.

Recruitment & Eligibility

Inclusion Criteria

isolated growth hormone deficiency (peak growth hormone level less than 10 ng/ml in response to arginine-insulin stimulation with cortisol responses and thyroid function tests), panhypopituitarism with appropriate thyroxine (normal free T4 level) and cortisol replacement (8-12 mg/m2/day) and non classic growth hormone deficiency (growth velocity less than 5 cm/year; peak growth hormone >10 ng/ml).

Exclusion Criteria

Taking medications other than the appropriate hormonal replacement(L-thyroxine, cortisol, estrogen or testosterone, DDAVP)

Arm && Interventions

Group	Intervention	Description
Growth Hormone	growth hormone	Growth hormone treatment 0.3 mg/kg/min

Primary Outcome Measures

Name	Time	Method
Reactive Hyperemic Response After 3 Months of Growth Hormone	3 months	Forearm blood flow (FBF) was measured using strain gauge venous occlusion plethysmography using a Hokanson EC6 plethysmograph (DE Hokanson Inc, Bellevue, WA) in the left arm. With this technique sphygmomanometric cuffs were placed on the arm at the wrist and on the upper arm. During measurement the wrist cuff was inflated to 200 mmHg to occlude flow to the hand which is primarily skin blood flow and the upper arm cuff is inflated to 40 mmHG for 10 out of every 15 second to occlude venous return. FBF was obtained by measuring arm expansion with an indium-in-silastic strain gauge. Data was recorded using PowerLab and Chart 4.0 (AD Instruments, Grand Junction, CO) on a Power Mac G4 computer (Apple, Cupertino, CA).For each subject two minutes of baseline FBF were recorded and then the upper arm cuff was inflated to 200 mmHg pressure for five minutes to occlude flow to the arm. It was then released and forearm blood flow was measured for the next minute.

Secondary Outcome Measures