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IMMULITE
Growth Hormone (hGH)
English
Intended Use: For in vitro diagnostic use
with the IMMULITE
Analyzers — for the quantitative
measurement of human growth hormone
in serum, as an aid in patient
management.
Catalog Number: L2KGRH2 (200 tests)
Test Code: GRH Color: Red
Summary and Explanation
Human growth hormone (hGH,
somatotropin) is a polypeptide originating
in the anterior pituitary. It is 191 amino
acids in length and has a molecular mass
of approximately 22,000 daltons. Its
metabolic effects are primarily anabolic. It
promotes protein conservation and
engages a wide range of mechanisms for
protein synthesis. It also enhances
glucose transport and facilitates the
buildup of glycogen stores. Another family
of peptide hormones, the somatomedins,
mediates its cascade of growth-promoting
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actions.
Measurement of hGH is primarily of
interest in the diagnosis and treatment of
various forms of inappropriate growth
hormone secretion. Clinical disorders of
hyposecretion include dwarfism and
unattained growth potential.
Hypersecretion is associated with
gigantism and acromegaly.
Caution must be exercised in the clinical
interpretation of growth hormone levels.
These vary throughout the day, making it
difficult to define a reference range or to
judge an individual's status based on
single determinations. Many factors are
known to influence the rate of growth
hormone secretion, including periods of
sleep and wakefulness, exercise, stress,
hypoglycemia, estrogens, corticosteroids,
L-dopa, and others.
similarity to prolactin and placental
lactogen, earlier growth hormone
immunoassays were often plagued with
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Because of its
falsely high values in pregnant and
lactating women.
Because not all acromegalic individuals
have elevated baseline levels,
suppression tests based on glucose
loading are of value in this context. In
spite of the induced hyperglycemia, there
is rarely a decrease from baseline levels in
acromegaly.
Growth hormone-deficient individuals have
fasting/resting levels similar to those found
in healthy individuals. Various challenge
tests have therefore been devised to
differentiate these groups. Thus, with the
onset of deep sleep or after 15 to 20
minutes of vigorous exercise, growth
hormone levels normally show a rise.
Other tests of growth hormone
responsiveness are based on the
administration of L-dopa, arginine and
insulin. Propanolol or estrogen are
sometimes given in conjunction with the
primary stimulus to accentuate the
response.
A small number of cases of dwarfism have
been documented in which both the basal
level and the response to challenge
testing were normal. Such cases may
involve tissue insensitivity to either growth
hormone or the somatomedins, or the
presence of antibodies or immunoreactive
but biologically inactive growth hormone.
Principle of the Procedure
IMMULITE 2000 Growth Hormone is a
solid-phase, two-site chemiluminescent
immunometric assay.
The solid phase (bead) is coated with
murine monoclonal anti-hGH antibody.
The reagent contains alkaline
phosphatase (bovine calf intestine)
conjugated to a rabbit anti-hGH polyclonal
antibody. The reagent and hGH in the
sample are incubated together with a
bead coated with a murine anti-hGH
monoclonal antibody to form an
antibody-sandwich complex. Unbound
enzyme conjugate is then removed by a
centrifugal wash. Finally,
chemiluminescent substrate is added to
IMMULITE 2000 Growth Hormone (hGH) (PIL2KGRH-11, 2018-03-15)
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