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Key Features

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Essentials of Diagnosis
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  • Truncal adiposity, thin extremities, moon facies, muscle wasting, weakness, plethora, easy bruising, purple striae, decreased growth rate, and delayed skeletal maturation

  • Hypertension, osteoporosis, and glycosuria

  • Elevated urinary free cortisol, elevated midnight salivary cortisol

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General Considerations
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  • May result from

    • Excessive autonomous secretion of adrenal steroids (adrenal adenoma or carcinoma)

    • Excessive pituitary ACTH secretion (Cushing disease)

    • Ectopic ACTH or CRH secretion

    • Long-term exposure to exogenous glucocorticoids

  • Less commonly due to

    • Adrenal tumor

    • Adrenal hyperplasia

    • Pituitary adenoma

    • Extrapituitary ACTH-producing tumor

  • Usually iatrogenic in children younger than 12 years

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Clinical Findings

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  • Excess glucocorticoid

    • Adiposity, most marked on the face, neck, and trunk—a fat pad (buffalo hump) in the interscapular area is characteristic but not diagnostic

    • Fatigue

    • Plethoric facies

    • Purplish striae

    • Easy bruising

    • Osteoporosis and back pain

    • Hypertension and glucose intolerance

    • Muscle wasting and weakness

    • Retardation of growth and skeletal maturation

  • Excess mineralocorticoid

    • Hypokalemia and mild hypernatremia

    • Increased blood volume

    • Edema

    • Hypertension

  • Excess androgen

    • Hirsutism

    • Acne

    • Virilization

    • Menstrual irregularities

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Laboratory Findings
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  • Plasma cortisol values

    • Generally elevated with loss of normal diurnal variation

    • Measuring level at the expected nadir between midnight and 2 am is a sensitive indicator of the loss of diurnal variation

  • Serum electrolytes

    • Serum sodium and bicarbonate are mildly elevated, with metabolic alkalosis

    • Potassium may be low

  • Morning ACTH concentration is decreased in adrenal tumors and increased with ACTH- or CRH-producing pituitary or extrapituitary tumors.

  • Salivary cortisol obtained at midnight is a noninvasive but highly specific and sensitive test

  • 24-Hour urinary free cortisol excretion

    • Measurement of urinary free cortisol/creatinine ratio is a useful way to document hypercortisolism

    • However, midnight salivary cortisol is considered a more practical and specific alternative

  • Dexamethasone suppression testing

    • Suppression of adrenal function by a small dose (0.5–1.0 mg) of dexamethasone is seen in children who may have elevated urinary free cortisol excretion due to obesity, but not in children with an ACTH-secreting tumor or adrenal tumor

    • Larger doses (4–16 mg/d in four divided doses) of dexamethasone cause suppression of adrenal activity when the disease is due to ACTH hypersecretion by a pituitary tumor, whereas hypercortisolism due to adrenal adenomas or adrenal carcinomas is rarely suppressed

  • CRH stimulation test, in conjunction with petrosal sinus sampling, is used to

    • Distinguish pituitary and ectopic sources of ACTH excess

    • Assess lateralization prior to surgery

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Imaging
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  • Pituitary imaging may demonstrate a pituitary adenoma

  • Adrenal imaging by CT scan may demonstrate adenoma or bilateral hyperplasia

  • MRI and nuclear medicine studies of the adrenals may be useful in complex cases

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Treatment

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  • If possible, surgical removal is indicated in all cases of primary adrenal hyperfunction due to tumor

  • Glucocorticoids should be administered parenterally in pharmacologic doses during and after surgery until the patient is stable

  • Supplemental oral glucocorticoids, potassium, salt, and mineralocorticoids may be necessary until ...

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