Chem Path - Adrenal Disease

Question 1

Raised TSH, low t4, ↓Na ↑K ↓Glucose

What is this?

Answer 1

Schmidt’s Syndrome
AKA
Autoimmune Polyendocrine syndrome type 2 - most common cause of multiglandular failure

Causes hypothyroidism and adddison’s
Can also cause T1DM, Hypogonadism

Question 2

How do you test for Addison’s Disease?

Answer 2

Short SynACTHen test

Measure ACTH and Cortisol before starting 

Inject synthetic ACTH by IM injection 

Patient should start producing cortisol

If Pt doesn’t produce cortisol, then adrenals aren’t working.

Question 3

How do you test for Cushing’s?

Answer 3

Dexamethasone Suppression Test

Low dose: no suppression of cortisol = Cushings

Normally, even a small amount of dexamethasone would suppress production of cortisol.

However, this doesn’t tell us the cause. High dose does

High dose:
If cortisol falls by 50% = Cushings disease. This happens as high dose dexamethasone causes ↓ACTH

If cortisol remains high = Ectopic ACTH or Primary

Measure ACTH - if high = Ectopic, if low = primary

Question 4

Causes of cushings

Answer 4

Commonest: oral steroids

The others: 

    Pituitary dependent Cushing's disease (85% of rest) 

    Ectopic ACTH e.g. lung cancer (5% of rest) 

    Adrenal adenoma (10% of rest)