Adrenal Gland Disorders - Summary Notes

Adrenal Gland Disorders
Cortex:
Zona Glomerulosa
-


(Aldosterone) reg. by RAAS
Mineralocort. -




Fasciculatis Glucocorti. (Cortisol)
Zona
reg. by ACTH
-




↓
Zona Reticularis Androgens
-

(DHEA)
Adrenal Androgens are regulated by ACTH, instead ofGonadotrophins.

ADRENAL CORTEX + MEDULLA
Medulla -

Catecholamines -
Under control of SNS

le.g. Dopamine, Adrenaline, Noradrenaline).



Hygeradrenalism:
Conn's Syndrome
Primary Aldosteronism Aldosterone,
·


high
-




commonly due to adrenal adenoma or bilateral adrenal hyperplasia.
Classically causes Hypokalaemic Hypertension, but all patients will have
hypokalaemia with it.
·
not

·
can also cause
slighthypernatraemia, as RAAS also reabsorbs Nat.



Diagnosis:

Aldosterone -

Renin Ratio (ARR):screening test for Conn's.
·

measure renin and aldosterone.

suppressed aldosterone aldosteronism.
renin+
high primary
-




before.
control hypokalaemia with
supplementand control hypertension
·

must




Saline Infusion Test:give LL saline over 4 hours to measure aldosterone regulation.
·
We would expect
that Aldosterone is suppressed during volume expansion with Saline,
so high Aldosterone during this test:
Primary Aldosteronism.

cTor MRI is used to localise potential nodules/adenomas.
·




·
If this doesn't
work, adrenal veins are sampled for both sides to identify abnormal side.


Treatment:



Adrenolectomy:performed on
oversecreting side.


·
To control symptoms, can use spirindactone or
kt-sparing Diuretics (e.g. Amiloride).

, Cushing's Syndrome
Cortisol, tissue exposure
·
excess to cortisol over
long time
period. Features:

Hirsutism
-




ACTH Dependent:caused by Moon face, obesity
- -




pituitary ACTH oversecretion (Cushing's Disease) Buffalo hump
-
-




ectopic ACTHoversecretion (commonly small cell
lung carcinomal Purple Striae chest/back
-



on


ectopic CRH oversecretion Proximal
myopathy/ atrophy
-
-




-easy bruising
Cushing's Disease hypercortisolaemia as result
-

a
STRIAE BUFFALO HUMP
of
pituitary adenoma over
secreting ACTH.

ACTH Independent:
-




autonomous oversecretion of Cortisol by Adrenals. Caused by:
Adenoma/Carcinoma
-




-latrogenic, prolonged steroid treatment (e.g. COPD Beclometasonel
Adrenal micronodular
dysplasia
-




Adrenal macronadular hyperplasia
-




Diagnosis:

Dexamethazone Overnight suppression Test: Low Dose Dexamethazone

suppression Test:

1) Take 1
my Dexamethazone tablet at -10gm.
2) 9am, check Serum Cortisol. but
·
At same as overnight
Dexamethazone should suppress endogenous Cortisol to 150 nmol/L. instead the dose
serum
If Cortisol 50nmol/L 9am
Cushing's Syndrome. 48 hours.
=


at is given over

3) If
normal/ACTH =
ACTH dependent
-
·
Serum Cortisol measured
If ACTH due to feedback ACTH
=



independent
-
at4am after the 48h dose.



Midnight/Morning Salivary Cortisol.
Imaging:

1) Patient
chews
midnight morningto collectsaliva.
and MRI of Pituitary can
·

at
gum
2) lowest cortisol level is
usually midnight, highestis in morning. identify tumours.
If this variation is disturbed, there
mightbe Cushing's Syndrome. CT is used Adrenals
·
on or


Chestif
ectopic is suspected.
Treatment:



(works ofcases).
Surgery:
-

Trans-sphenoidal pituitary hypophysectomy in 50-60%
-

adrenal adenoma removal, or
complete adrenalectomy (can cause Nelson's Syndrome).
tumour removal.
ACTH
-secreting ectopic
-




Nelson's syndrome:high unregulated ACTH from pituitary tumour thatforms after adrenalectomy,
symptoms:skin hyperpigmentation, mass effects ofpituitary tumour.
·




-40% incidence after
adrenalectory.
·




Drugs: temporary solution.
·




·
aim to cortisol secretion
inhibit (e.g. Metyraprone, ketoconazole, Mitotane).
·
can also aim to inhibit
ACTH secretion IDoyamine agonists like Cabergoline).