Hyperaldosteronism

Hyperaldosteronism (皮質醛固酮血症)

病因:

 Primary: (腎上腺d/o, ↑aldo -> renin↓)

   Neoplasm: Adrenal hyperplasia (60%), Adenoma (Conn’s synd, 35%), Carcinoma (5%)

   Glucocorticoid-remediable aldosteronism (GRA); (ACTH-dep.->aldo.↑, Rearranged promoter)

 Secondary: (腎上腺外d/o, renin↑-> aldo.↑)

   Primary reninism (renin secreting tumor- rare)

   Secondary reninism

     Renovascular dz: RAS, 惡性高血壓

     水腫+有效動脈容積減少: CHF, LC, nephrotic synd

     脫水, 利尿劑, T2D, Bartter’s (defective Loop (Na/K/2Cl transporter≒使用lasix), Gitelman’s (defective renal Na/Cl transporter≒Thiazide)

 Non-aldosterone mineralocorticoid excess (mimic hyperaldosteronism)

   11β-HSD deficiency (先天, 無法將cortisol 去活化 ->which also bind to non-selective mineralocorticoid receptor)

   黑甘草(black licorice): glycyrrhizic acid)( 11β-HSD抑制劑), 嚴重hypercortisolism,

Glucocorticoid-remediable aldosteronism (GRA)

-also describable as aldosterone synthase hyperactivity,

-an AD disorder in which the increase in aldosterone secretion produced by ACTH is no longer transient.


臨床表現:

  高aldo ->高血鈉, HTN; 低鉀; 酸分泌出(代謝性鹼)  


診斷:

-a subnormal renin level (< 2 ng/mL/h) can be found in 30% of patients with essential hypertension; 
-thus, a low renin level is not specific for primary aldosteronism.

In order to improve the sensitivity of a screening test for primary hyperaldosteronism, a ratio of plasma aldosterone (PA) activity to plasma renin activity (PRA) can be calculated. A 

篩檢test:
PA/PRA ratio (早晨抽) ≥ 20 (with a PA ≥15 ng/dL) Sn/Sp 100% / 80%, indicating the need for further study.

Others use a ratio ≥ 30 (PA level ≥ 20 ng/dL), Sn/Sp 90% / 91%.

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1° Hyperaldosteronism

　

47, F, p/w persistent HTN (refractory to conventional tx).also polyuria, esp. nocturia,↑thirst (polydipsia).

Profound muscle weak & cramps (HypoK). Leg numbness, tingling (paresthesias), intermittent HA. N° HR, diastolic HTN (130/100). PE: minor diffuse retinal arteriolar narrowing (grade I hypertensive changes), No LAD or JVD; no mur or rubs; abd –benign w/o bruits; Slow DTRs.

Lytes: hyperNatremia, hypoMagnesemia , hypoK, (↑Ur K)

ABG: metab alkalosis. ↑aldosterone (plasma/Ur).

↓renin; 2L normal saline infusion in 4h fail to suppress [aldo] <10 ng/dL; abn glucose tolerance test;

Load test w/ Na produces hypoK. 

ECG: LVH (due to HTN); flat T, prolong QT, prominent U (hypoK).

MR : small Left adrenal mass; adrenal vein catheterization àunilat (L-sided)↑aldo.

　

(1° hyperAldo cause <1% case of HTN, female, may a/w MEN I synd (Wermer’s synd: tumors of parathyroid, pituitary and pancreatic islets))

(E: 1) Conn’s synd (mc E)- adrenocortical adenoma, usu single, unilat,↑[aldo]);

      2) 1° bil adrenal hyperplasia. 

      3) adrenal cancer. (rare).  HyperAldo – typically inv the trial of HTN, hypoK, Low renin.

In hyperplasia, elevated baseline aldo ↑when pt assumes採取upright position. While Conn’s synd it dose Not.

In hyperplasia, it’s sensitive to fludrocortisone suppression of renin, whereas Conn’s synd Not.

Cx : (renal damage, MI, stroke)- (2° to chronic HTN), rhabdomyolysis, arrhythmia, paralysis fr hypoK; carpopedal spasm/tetany due to alkalosis.

　

Tx:

Spironolactone – Aldo antagonist.  (control HTN, hypoK).

Excision of Conn’s adenoma

  May cause postOP hypoaldo. (HTN,hyperK) (due to long-standing supression of contralat adrenal. )

Bil adrenal hyperplasia

  Spironolactone, anti-hypertensive

  Dexamethasone suppression, since even w/ bil adrenectomy, HTN continues despite correction of hypoK.

Generally unresponsive to ACEI.