TOC | STAT | Endo
Acute Adrenal Insufficiency or Adrenal Crisis (Addison's Disease)
Weakness (99%), Pigmentation of skin (98%), Weight loss (97%), Abdominal pain (34%), Nausea & Vomiting, diarrhea, Salt craving (22%), Diarrhea (20%), Constipation (19%), Syncope (16%), Vitiligo (9%), fever, lethargy.
Hypovolemia, orthostatic hypotension, tachycardia, hyponatremia, hyperkalemia
Low serum cortisol level, & inadequate serum cortisol response 30 or 60 min after IV or IM Cortrosyn (syntheticACTH) 0.25 mg (normal is >18-20 ug/dl with increment of 7 ug/dl or greater)
Obtain baseline serum cortisol and ACTH levels. Normal response is indicated when the cortisol level at least doubles in response to ACTH stimulation.
Plasma ACTH levels are typically elevated in patients with primary adrenal failure and are normal or unmeasurable in patients with primary ACTH deficiency.
CRH may help distinguish between hypothalamic and pituitary etiologies of secondary adrenal insufficiency. If an insulin tolerance test shows no cortisol response to hypoglycemia, secondary hypoadrenalism is present. If in such a patient a CRH test elicits a prompt ACTH release, then, by inference, hypothalamic disease is likely; if CRH does not elicit release of ACTH, then presumably the lesion is in the pituitary.
|Laboratory findings in Adrenal Insufficiency|
|Secondary Adrenal Insufficiency
from Pituitary Etiology:
|Secondary Adrenal Insufficiency
from Hypothalamic Etiology:
Acute Adrenocortical Insufficiency
Causes of Primary Adrenal Insufficiency
Causes of Secondary Adrenal Insufficiency
Testing Adrenal Function
The principal tests used to evaluate adrenal function include measurements of plasma ACTH and cortisol and of urinary 17-OHS and 24-hour urinary free cortisol.
Measurement of plasma cortisol and ACTH
The following are some well-standardized tests for the evaluation of adrenal function:
To determine pituitary-adrenal suppression, 1 mg of dexamethasone (a cortisol analogue) is given orally at 11:00 P.M., and the plasma cortisol level is measured at 8:00 A.M. the next day. A value of less than 5 mg/dl is normal.
To measure adrenal response, 0.25 mg of Cortrosyn /cosyntropin (synthetic ACTH) is given intravenously. The plasma cortisol is measured at 0 and 30 or 60 minutes; a value of 20 mg/dl at any time during the test denotes normal adrenal responsiveness.
To assess pituitary-adrenal reserve, 3 g of metyrapone is administered orally at midnight, and plasma cortisol and 11-deoxycortisol (compound S) levels are obtained at 8:00 A.M. the next day. Metyrapone inhibits 11-hydroxylation, which leads to a fall in cortisol and a rise in ACTH. If the pituitary-adrenal reserve is intact, the plasma cortisol level should be less than 5 mg/dl and the 11-deoxycortisol level greater than 10 mg/dl.
An alternative method of measuring pituitary-adrenal reserve involves the intravenous administration of insulin, 0.15 U/kg. The ensuing hypoglycemia should elicit both cortisol (normal, 20 mg/dl) and growth hormone (> 8 ng/ml) responses. This test should be carried out in the presence of a physician prepared to administer 25 ml of 50 percent glucose intravenously in case of a hypoglycemic reaction.
To measure pituitary reserve of ACTH, ovine CRH can be administered in a dose of 1 mg/kg body weight. Both ACTH and plasma cortisol levels rise in normal individuals. This test can be performed at any time of day, but the sensitivity is greatest in the afternoon.
Plasma ACTH can be determined by immunoradiometric assay (IRMA), employing antibodies to both the N- and C-terminal domains of the hormone. Unlike radioimmunoassay, IRMA can reliably distinguish low, normal, and elevated ACTH levels.9
Urinary 17-OHS level
24-Hour urinary free cortisol
Scientific American Medicine 2000
See also adrenal_insufficiency2005 (JAMA Vo. 294, Nov.16,2005)
Diagnosis of Adrenal Insufficiency