Growth hormone is pulsatile
throughout the day
and is not useful for
the diagnosis of acromegaly.
The best screening test
is a serum IGF-1
Excess growth hormone is confirmed
with an oral glucose tolerance test
because glucose normally suppresses
growth hormone levels
to less than
one nanogram per ml.
Growth hormone levels greater than
one nanogram per ml
are diagnostic of
growth hormone excess.
Anterior pituitary MRI should
once growth hormone excess is
confirmed by chemically
to rule out
a pituitary lesion.
Acromegaly is the clinical syndrome
that occurs when a pituitary tumor
secretes excessive amounts of growth hormone
in an adult patient.
Prior to puberty, patients with
growth hormone-secreting tumors
develop excessive longitudinal growth
and gigantism above normal for age.
Let's go through some of the
external features of acromegaly again.
In the head, there may be prominence
of the brow and jawline.
There may have been
an enlarged skull.
There may be facial edema
and coarsening of facial features,
excessive spacing between the teeth
usually of the lower jaw,
and finally, macroglossia
or enlargement of the tongue.
The skin can demonstrate
thickening and skin tags,
and the hands and feet
may be disproportionately large.
In the joints, arthritis may
be a manifestation,
and other internal features include
diabetes mellitus, hypertension,
colon polyps, and excessive perspiration
Obstructive sleep apnea is usually caused
by excessive growth of tissue
in the upper airway, and in and around the mouth,
along with macroglossia,
which leads to obstructive symptoms
Left ventricular hypertrophy
can occur in the heart,
and these patients may present
And then finally, there are increased
rates of cancers,
particularly of the colon, esophagus,
as well as thyroid,
and even melanomas.
The clinical poll here is
in clinical practice.
Because of the increased number
of colonic polyps,
patients are predisposed
to colon cancers,
and will often present, as a first feature,
with blood in the stool.
The treatment of acromegaly requires
transsphenoidal tumor resection,
and surgery is the only treatment
that is potentially curative.
Remission is achieved when IGF-1 levels
are within the normal range for age,
and the response of growth hormone
to glucose tolerance test returns to normal.
Patients not achieving remission require
injectable somatostatin analogues
growth hormone secretion.
High-dose dopamine agonist therapy
is marginally effective
when the tumor
Pegvisomant, a growth hormone
is then used to lower
but it works in the peripheral tissues
as an antagonist to growth hormone,
and does not decrease
growth hormone production by the tumor.