Question

Addison's disease has many symptoms include pigmintation of skin, weightloss, abdomen pain, diarrhea, reduce appetite, weak muscles, low blood pressure and hypoglycemia may also occur. If you were a doctor facing a patient with that type of symptomatology, what type of laboratory investigations would you order?

Answer 1

Addison's disease is also known as Adrenal Insufficiency. In this, adrenal cortex is defective and there is decrease in glucocorticoids, mineralocorticoids and adrenal androgens.

It is of two types: Primary and Secondary. Primary means disorder of Adrenal Cortex only and Hypothalamus and pituitary are intact. Secondary means disorder of pituitary or Hypothalamus and Adrenal Cortex is intact. Primary has increased levels of ACTH leading to pigmentation of the skin. Whereas secondary has low ACTH levels. Primary has decreased aldosterone levels leading to diuresis. Secondary has normal aldosterone levels. Primary (80%) is much more common than secondary(20%)

Work up will be:-

• Glucocorticoids level- decreased
• Mineralocorticoids level- decreased
• Androgens- decreased
• ACTH levels- High leading to pigmentation
• Serum potassium- High
• Serum Na- Low.
• Causative agents test- autoimmune (antibodies against 21-Hydroxylase enzyme) will be positive.
• Screening test- 8 AM PLASMA CORTISOL. Normal values >20 microgram/dL. If it is <3 microgram/dL, it is adrenal insufficiency. If it is between 3-20 microgram/dL, go for confirmatory test.
• Confirmatory test: ACTH STIMULATION TEST. 250 microgram of ACTH is given intravenously or intramuscularly. Then cortisol levels are checked after 1 hour. If >20 microgram/dL, it is normal. If <20 microgram/dL it is adrenal insufficiency.