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8 out of 8

In Addison’s disease, most diagnostic test is: (DNB June 2010)

A Serum Na+, K +, rennin

B Serum Na+, K +, saline suppression

C Serum creatinine/urea ratio

D ACTH stimulation test

Ans. D

ACTH stimulation test

Tests of adrenal insufficiency

1. Na+ & K+ (due to mineralocorticoid), (MCQ)

2. Glucose(due to cortisol). (MCQ)

3. Ca2+,(MCQ)

4. Eosinophilia, (MCQ)

Extra Edge: (Ref. Hari 18th ed. Pg- 2956)

1). Hyponatremia is a characteristic feature in primary adrenal insufficiency

2). Hyperkalemia is present in 40% of patients at initial diagnosis.

3). Glucocorticoid deficiency also results in slightly increased TSH concentrations that normalize within days to weeks after initiation of glucocorticoid replacement.

Diagnosis (Ref. Hari-18th ed., Pg. 2959 Fig 342.15)

1). ACTH stimulation test (Most confirmatory Test)

The diagnosis of adrenal insufficiency should be made only with ACTH stimulation testing to assess adrenal reserve capacity for steroid production. In brief, the best screening test is the cortisol response 60 min after 250 μg of cosyntropin given IM or IV. Cortisol levels should be 18 μg/dL.

2). If the response is abnormal, then primary and secondary adrenal insufficiency can be distinguished by measuring aldosterone levels from the same blood samples. In secondary, but not primary, adrenal insufficiency, the aldosterone increment will be normal [≥ 150 pmol/L (5 ng/dL)].

3). 21-Hydroxylase adrenal autoantibodies: +ve in autoimmune disease in >80%.

4). In Addison disease - Increase Plasma renin and reduce plasma aldosterone level:

In secondary adrenal insufficiency both plasma renin and plasma aldosterone level are raised.

5). Addison’s disease is associated with serum cortisol <3 mcg/dl

Extra Edge: Low plasma cortisol (<3 mcg/dl) at 8:00 AM is diagnostic especially if accompanied by simultaneous elevation of plasma ACTH level (usually >200 pg/ml)

Treatment of Addison disease

1). Replace steroids: 15-25mg hydrocortisone daily, in 2-3 divided doses.

2). Mineralocorticoid replacement is needed if postural hypotension: fludrocortisone from 50-200 micro g daily.

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