ENDOCRINE SYSTEM
Certain endocrine disorders cause chronic disease in pediatric
patients (see Chapter 27
).
It is beyond the scope of this chapter to discuss these diseases in detail, but
some acute disorders frequently encountered in the PICU are highlighted in the following
sections.
Adrenal
Abnormalities of the adrenal axis result in either deficient or
excessive production of glucocorticoids or mineralocorticoids, or both. Many of
these disorders are diagnosed and treated as they are in adults. Special reference
should be made to the problems of congenital adrenal hyperplasia, pheochromocytoma,
and iatrogenic chronic adrenal insufficiency.
Congenital Adrenal Hyperplasia
Congenital adrenal hyperplasia is an autosomal recessive disorder
that describes deficiencies in either 21-, 11-, or 17-hydroxylase. 21-Hydroxylase
deficiency is the most common disorder, and it causes problems from cortisol and
aldosterone deficits as well as from the buildup of active intermediary metabolites.
[247]
21-Hydroxylase deficiency in children can
be either partial (simple virilizing form) or more complete (salt-losing form); at
birth, affected children demonstrate masculinization of the external genitalia, and
those with the more complete deficiency show a progressive salt-losing state (i.e.,
loss of sodium and elevation of potassium). The condition is usually manifested
in the first few weeks of life as a history of feeding difficulty, vomiting, and
failure to thrive—a clinical and historical course suggestive of pyloric stenosis.
If the deficiency is not diagnosed and treated early in life, affected children
can suffer severe cardiovascular collapse. A blood sample should be obtained for
electrolytes, glucose, and if the diagnosis has not been established, adrenocorticotropic
hormone (ACTH), cortisol, aldosterone, and plasma renin activity.
Treatment is aggressive support of intravascular volume and myocardial
function, glucose, and replacement of the deficient hormones. Cortisol can be replaced
with the oral administration of hydrocortisone at a dose of 25 mg/m2
/day
divided into three doses; if the child is unable to tolerate oral medication, cortisone
acetate can be administered intramuscularly in a dose of 37.5 mg/m2
/day
given every 3 days. For emergency therapy, when the oral route is not possible and
perfusion of the muscle bed is poor, hydrocortisone acetate can be used intravenously
at a bolus dose of 1.5 to 2.0 mg/kg and then 25 to 250 mg/day in divided doses.
Mineralocorticoid is replaced with fludrocortisone acetate, 0.05 to 0.2 mg/day orally;
these patients usually require the addition of salt to their daily diet.[248]
Deficiencies of 11- and 17-hydroxylase do not result in salt wasting; masculinization
and hypertension are the common initial signs.[249]
Pheochromocytoma
Less than 5% of pheochromocytomas are diagnosed in children.
As a rule, these tumors are more often confined to the adrenal medulla, but they
can occur anywhere throughout the sympathetic chain.[250]
The clinical signs and symptoms of excessive catecholamines are the same as those
in adults.
Iatrogenic Chronic Adrenal Insufficiency
Long-term daily use of steroids for the treatment of asthma, nephrotic
syndrome, and malignancies is common. It is important to remember that a hypoadrenal
state can result and produce potential risk during severe illness and stress crises.
[251]
In children, it is also important to remember
that topical steroids have been reported to depress the production of ACTH. Replacement
of stress-level steroids (three times the daily replacement dose) is required.
