Researchers would like to determine normal ranges for hormone levels and to learn more about the genetics involved in hormone production and action. Researchers will take samples of blood, urine, saliva, and stool from healthy children ages 5-17 in order to study different aspects of hormones.

Establishing a range of normal hormone levels in children will make diagnosing illnesses with abnormal levels of hormones much easier. Hormone levels in the body can change throughout the day. By collecting samples at different times researchers hope to learn more about the normal daytime and nighttime patterns of hormone secretion. Because some hormone levels change with body size, researchers will also take measurements of patient's body composition.

This study will involve children and observe them as inpatients or as outpatients. <TAB>

We wish to obtain blood, urine, saliva, and stool specimens from healthy children ages 2-18 years for use in establishing the normal ranges of levels of hormones and the variations in genes that are important for hormones to act. Such hormone values are extremely important to allow endocrinologists to determine when hormone levels are truly abnormal in children suspected of an illness. Because the values of some hormones change with body size, we will obtain measurements of body composition when studying such hormones. Children participating in this study may be studied in the outpatient clinic (at most 2 blood draws) or as inpatients on the pediatric ward (for frequent blood sampling using an intravenous line over a 24-hour period). Other studies that may be performed as part of this study include ultrasound examinations of the thyroid, adrenal, ovaries or testes, and x-ray of the hand and wrist for bone age determination.

• INCLUSION CRITERIA:

Good general health.

Age 2 to 18 years.

EXCLUSION CRITERIA:

Volunteers will be excluded for the following reasons:

Presence of renal, hepatic, gastrointestinal, most endocrinologic (e.g., Cushing's syndrome) or pulmonary disorders (other than asthma not requiring continuous medication);

Individuals who have, or whose parent or guardians have, current substance abuse or a psychiatric disorder or other condition which, in the opinion of the investigators, would impede the ability to give informed consent or possibly hinder completion of the study;

Subjects who regularly use prescription medications are not eligible. The use of over-the-counter medications will be reviewed on a case-by-case basis;

For those sub-studies involving MRI, inability to undergo MRI (e.g., volunteers with metal within their bodies including cardiac pacemakers, neural pacemakers, aneurysmal clips, shrapnel, ocular foreign bodies, cochlear implants, non-detachable electronic or electromechanical devices such as infusion pumps, nerve stimulators, bone growth stimulators, etc. that are contraindications).