Easy Pediatrics

The child initially is normal; manifestations similar to those seen in idiopathic pituitary growth failure gradually appear and progress.

When complete or almost complete destruction of the pituitary gland occurs, signs of pituitary insufficiency are present.

Atrophy of the adrenal cortex, thyroid, and gonads results in loss of weight, asthenia, sensitivity to cold, mental torpor, and absence of sweating.

Sexual maturation fails to take place or regresses if already present. There may be atrophy of the gonads and genital tract with amenorrhea and loss of pubic and axillary hair.

There is a tendency to hypoglycemia. Growth slows dramatically. Diabetes insipidus may be present early but tends to improve spontaneously as the anterior pituitary is progressively destroyed.

If the lesion is an expanding tumor, symptoms such as headache, vomiting, visual disturbances, pathologic sleep patterns, decreased school performance, seizures, polyuria, and Continue reading »

Cortisol levels in blood are normally elevated at 8 a.m. and decrease to less than 50% by midnight except in infants and young children in whom a diurnal rhythm is not always established.

In patients with Cushing syndrome this circadian rhythm is lost, and cortisol levels at midnight and 8 a.m. are usually comparable.

Urinary excretion of free cortisol is increased. This is best measured in a 24-hr urine sample and is expressed as a ratio of micrograms of cortisol excreted per gram of creatinine. This ratio is independent of body size and completeness of the urine collection.

A single-dose dexamethasone suppression test is often helpful; a dose of 25–30 ?g/kg (maximum of 2 mg) given at 11 p.m. results in a plasma cortisol level of less than 5 ?g/dL at 8 a.m. the next morning in normal individuals but not in patients with Cushing syndrome.

A glucose tolerance test is often abnormal despite elevated levels of insulin.

Levels of serum electrolytes are usually normal, but potassium may be decreased, especially in patients with tumors that secrete ACTH ectopically.

After the diagnosis of Cushing syndrome has been established, it is necessary to determine whether it is caused by a pituitary adenoma, an ectopic ACTH-secreting tumor, or a cortisol-secreting adrenal tumor. ACTH concentrations are usually suppressed in patients with Continue reading »