Clinical utility of cycle exercise for the physiologic assessment of growth hormone release in children

Article Abstract:

Children often receive medical evaluations because of short stature. It was estimated that 14,500 children in the United States are deficient in growth hormone. However, this large number does not account for short children with variants of normal growth or suspected growth hormone deficiency. A reliable test to screen for growth hormone deficiency is needed. Growth hormone is released intermittently or periodically; consequently, a single measurement of growth hormone at one point in time may not reflect the true amount of growth hormone secretion. Other tests of growth hormone secretion involve the use of physiologic or drug activation of growth hormone release. Although the amount of activation by a drug can be controlled, drugs may produce adverse side effects or nonphysiologic levels of growth hormone release. In addition, growth hormone deficiency tests involving drugs may be difficult and tedious to perform. On the other hand, physiologic conditions, such as sleep or exercise, represent naturally occurring events that activate the release of growth hormone. The use of 15 minutes of exercise on a cycle to assess growth hormone deficiency was examined in healthy children. Exercise tests revealed that blood levels of growth hormone were 7 micrograms per liter (ug/L) in 9 of 10 children. The level of growth hormone recorded on one occasion, 27.1 ug/L, varied from that recorded on the other test day, 19.8 ug/L. However, the exercise test was clinically valid because greater than diagnostic levels of growth hormone were recorded on both test days. Thus, exercise tests are useful in assessing growth hormone deficiency in healthy children. (Consumer Summary produced by Reliance Medical Information, Inc.)

Testing, Physiological aspects, Cycling, Dwarfism, Pituitary, Pituitary dwarfism

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Diagnostic limitations of spontaneous growth hormone measurements in normally growing prepubertal children

Article Abstract:

Adequate levels of growth hormone (GH) are needed for normal growth. GH levels can be determined by frequent overnight sampling or by tests that trigger the secretion of GH. Studies have shown that tests that measure GH may not accurately assess GH status in some patients. The spontaneous GH secretion test was tested for accuracy among children of normal stature, children with constitutional growth delay thought to have normal GH secretion, and GH-deficient children. GH levels below three nanograms per ml were considered GH-deficient. Twelve of the 45 (26.6 percent) normally growing children had low GH levels. On the basis of overnight GH sampling alone, 25 percent would have been considered GH-deficient. Tests that stimulate GH release to measure spontaneous levels of GH had some margin of error. Accurate GH levels were not detected by any direct or indirect method of testing performed alone. Identification of GH deficiency is made when these methods are used in combination with subnormal yearly growth rates determined for longer than one year. (Consumer Summary produced by Reliance Medical Information, Inc.)

Diagnosis, Children, Growth, Growth disorders, Child development deviations, Developmental disabilities

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The value of urinary growth hormone determination for assessment of growth hormone deficiency and compliance with growth hormone therapy

Article Abstract:

Measuring the level of growth hormone in the urine may a useful means of monitoring growth hormone deficiency and compliance with growth hormone therapy. Typically, growth hormone deficiency is diagnosed based on blood levels using a test that measures the integrated concentration of growth hormone (IC-GH). IC-GH levels and urine growth hormone levels were measured in 46 children aged six to 19. IC-GH levels correlated strongly with urine growth hormone levels. Although urine growth hormone levels were not accurate enough to be used for confirmation of growth hormone deficiency, they may be useful for general screening of growth hormone deficiency and for monitoring therapy. Measuring growth hormone in the urine is a simpler, faster and less invasive procedure than measuring IC-GH, and it does not require specialized skills and equipment.

Analysis, Usage, Hormone therapy, Urine, Urinalysis

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