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E32 Endocrinology
Adrenal Cortex
Toronto Notes 2019
Mineralocorticoid Excess Syndromes
hPRA
hPAC PAC:PRA ratio = 10 (277 in SI units)
Investigate for causes of secondary hyperaldosteronism
Renovascular HTN Diuretic use Renin-secreting tumour Malignant HTN Coarctation of the aorta
Hypertension and Hypokalemia
Plasma renin activity (PRA) Plasma aldosterone concentration (PAC)
iPRA
hPAC
PAC:PRA ratio ≥20 (≥555 in SI units)
and
PAC ≥15 ng/dL (≥416 pmol/L)
Investigate for Primary aldosteronism
iPRA iPAC
Investigate for Congenital adrenal hyperplasia Exogenous mineralcorticoid DOC-producing tumour Cushing’s syndrome 11-β-HSD deficiency Altered aldosterone metabolism Liddle’s syndrome Glucocorticoid resistance
Figure 14. Approach to mineralocorticoid excess syndromes
Definition
• primaryaldosteronism(PA):excessaldosteroneproduction(intra-adrenalcause)(previouslycalled hyperaldosteronism)
• secondaryaldosteronism(SA):aldosteroneproductioninresponsetoexcessRAAS(extra-adrenalcause)
Etiology
• primaryhyperaldosteronism
■ aldosterone-producing adrenal adenoma (Conn’s syndrome) ■ bilateral or idiopathic adrenal hyperplasia
■ glucocorticoid-remediable aldosteronism
■ aldosterone-producing adrenocortical carcinoma
■ unilateral adrenal hyperplasia
• secondaryhyperaldosteronism
Clinical Features
• HTN
• hypokalemia(±mildhypernatremia),metabolicalkalosis
• normalK+,hyponatremiainSH(loweffectivecirculatingvolumeleadstoADHrelease)
• increasedcardiovascularrisk:LVhypertrophy,atrialfibrillation,stroke,andMI
• fatigue,weakness,paresthesia,headache;severecasespresentwithtetany,intermittentparalysis
Diagnosis
• investigateplasmaaldosteronetoreninratioinpatientswithHTNandhypokalemia
• confirmatorytestingforPA:aldosteronesuppressiontest(demonstrateinappropriatealdosterone
secretion with ECF volume expansion) • imaging:CTadrenalglands
Table 23. Diagnostic Tests in Hyperaldosteronism
Test
Plasma aldosterone to renin ratio (PAC/PRA) Salt loading test (confirmatory test)
A) Oral test
B) IV saline test
Treatment
Primary Hyperaldosteronism
Elevated (aldo,renin)
urine aldosterone
plasma aldosterone
plasma aldosterone concentration >280 pmol/L (140-279 indeterminant range)
Secondary Hyperaldosteronism
Normal (aldo,renin)
Not performed if normal PAC/PRA
• inhibitactionofaldosterone:spironolactone,eplerenone,triamterene,amiloride(actonsodiumchannels) • surgicalexcisionofadrenaladenoma
• secondaryhyperaldosteronism:treatunderlyingcause