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Endocrine hypertension

Except for:1. acromegaly, 2. thyrotoxicosis, 3. hypothyroidism, 4. primary hyperparathyroidism

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A few remarks on:

Primary hyperaldosteronism Congenital adrenal hyperplasia

(due to: 17-hydroxylase deficiency, 11-hydroxylase deficiency

Cushing’s syndrome Pheochromocytoma Hypertension of renal origin

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PRIMARY HYPERALDOSTERONISM Sodium and fluid retention, expansion of ECFV

and plasma volume, increased cardiac output Vasoconstriction, increased total peripheral

resistanceTypical features: hypertension, hypokalemia,

metabolic alkalosis, supression of the renin-angiotensin system ( PRA),

Source of aldosterone: adenoma (75%), micro- or macronodular hyperplasia (idiopathic hyperaldosteronism) of zona glomerulosa

K+ depletion impaired glucose tolerance, impaired urinary concentrating ability, postural hypotension

Other hormones of zona glomerulosa: DOC (deoxycorticosterone), corticosterone, 18-OH-corticosterone

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Clinical featuresSymptoms of hypokalemia: fatigue, loss of stamina, weakness,

lassitude, increased thirst, polyuria, paresthesias, orthostatic hypotension

Symptoms of alkalosis: a possitive Trousseau or Chvostek signHypertensionNo edemaThe most common cause of hypokalemia in hypertensive patients is

diuretic therapy!A low Na+ diet, by reducing delivery of Na+ to aldosterone-sensitive sites

in distal nephron, can reduce renal K+ secretion and thus correct hypokalemia.

Average diet contains >120 mmol of Na+ per dayHormonal assessment:Plasma renin activity (PRA)Plasma aldosteroneUrinary aldosterone excretion

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Hormonal assessment

Basal conditions: around 8 A.M. after at least 4 hrs. of recumbency (unrestricted salt diet): PRA, plasma aldosterone

Stimulation test: a 4-hour upright posture furosemide i.v.

ADENOMA: suppression of PRA, high basal plasma aldosterone level, no significant change or a frank decrease on stimulation.

HYPERPLASIA: suppression of PRA, lower basal plasma aldosterone level (< 25 ng/dl), an increase on stimulation

Saline infusion test (suppression): 2 L 0.9% NaCl over 2 hrs.: no suppression of plasma

aldosterone

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Location of adenomaCT or MRI imagingAdrenal scintigraphy: 131I-iodocholesterol Adrenal vein catheterization: measurement and comparison of

aldosterone levels

TreatmentAdenoma: unilateral adrenalectomyHyperplasia: spironolactonePreoperative preparation: Spironolactone: 200-300 mg/d (4-6 weeks), maintenance dose 75-100

mg/d; reduces ECFV, promotes K+ retention, activates the suppressed renin-angiotensin system, prevents postoperative hypoaldosteronism.

Side effects: rashes, gynecomastia, impotence, dyspepsiaAmiloride: 20-40 mg/dOther antihypertensive drugs (Ca channel blockers)

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Treatment

Basal conditions: around 8 A.M. after at least 4 hrs. of recumbency (unrestricted salt diet): PRA, plasma aldosterone

Stimulation test: a 4-hour upright posture furosemide i.v.

ADENOMA: suppression of PRA, high basal plasma aldosterone level, no significant change or a frank decrease on stimulation.

HYPERPLASIA: suppression of PRA, lower basal plasma aldosterone level (< 25 ng/dl), an increase on stimulation

Saline infusion test: 2 L 0.9% NaCl over 2 hrs.: no suppression of plasma

aldosterone

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PHEOCHROMOCYTOMA

Arises from chromaffin cells in the sympathetic nervous system that release A, NA, and in some cases D

0.1% of patients with diastolic hypertension have pheochromocytomas

In 50% of patients symptoms of are episodic/paroxysmal

Symptoms during or following paroxysms: headache, sweating, facial pallor, cold and moist hands, forceful heartbeat with or without tachycardia, anxiety or fear of impending death, tremor, seizures, fatigue or exhaustion, nausea and vomiting, abdominal or chest pain, visual disturbances

Symptoms between paroxysms: increased sweating, heat intolerance, cold hands and feet, weight loss, constipation, wide fluctuations of blood pressure, postural hypotension

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With time attacks usually increase in frequency but do not change much in character. Glycosuria after an attack! ( glycogenolysis, insulin release). Paroxysms may be induced by deep palpation of the abdomen Typically, commonly used antihypertensive drugs are ineffective

Location Over 95% of pheochromocytomas are found in the abdomen, and 85% of these are in the

adrenal. Chest: heart, posterior mediastinum Multiple tumours in less than 10% of adults Tumours are usually small (< 100 g) Incidence of malignant tumours: 10%

Complications of hypertension are common: hypertensive retinopathy or nephropathy, congestive heart failure, CVA, MI.

Common causes of death: MI, CVA, arrhythmias, irreversible shock, renal failure, dissecting aortic aneurysm.

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Hormonal assessment Plasma catecholamines Urinary catecholamines Urinary metoxycatecholamines Urinary VMA (vanillylmandelic acid)Glucagon test: 1 mg i.v.,

phentolamine (Regitine) should be available to terminate the induced episode. Sensitivity: 90%.

Clonidine suppression test: 0.3 mg of clonidine p.o. 2-3 hrs. before sampling of blood for plasma NA level: no reduction

of plasma NA

Trial of phenoxybenzamine (Dibenzyline): 2-receptor blocker

Localization of tumour CT or MRI imaging (bright image with T2-weighting) Scintigraphy: 131I-metaiodobenzylguanidine (MIBG) Venous catheterization for catecholamines assessment

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Management

Medical preoperative preparation: Phenoxybenzamine (Dibenzyline) propranolol when marked tachycardia or

arrhythmias Prazosin propranolol LabetalolTreatment of attacks: Phentolamine (Regitine) 5-10 mg i.v. Sodium nitroprusside – i.v. infusionSurgery: Caution: induction of anesthesia Phentolamine or sodium nitroprusside i.v. infusion After tumour removal: blood volume expansion with whole blood, plasma, or other fluids

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RENOVASCULAR HYPERTENSION

The most common cause of renin-dependent hypertension

The most common correctable cause of secondary hypertension (present in 1-4% of patients with hypertension)

Causes:

1. Atherosclerosis,

2. Fibromuscular hyperplasia,

3. Parenchymal lesions, hydronephrosis

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When renovascular hypertension should be suspected?

1. Severe hypertension (diastolic pressure > 120 mmHg with either progressive renal insufficiency or refractoriness to agressive medical therapy (particularly in a smoker or with other evidence of occlusive arterial disease);

2. Accelerated or malignant hypertension with grade III or grade IV retinopathy;

3. Moderate to severe hypertension in a patient with diffuse atherosclerosis or a detected assymetry of kidney size;

4. An acute elevation in plasma creatinine level in a hypertensive patient that is either unexplained or follows therapy with an ACE inhibitor;

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5. An acute rise in blood pressure over a previously stable baseline;

6. A systolic-diastolic abdominal bruit;

7. Onset of hypertension below age 20 or above age 50;

8. Moderate to severe hypertension in patients with recurrent acute pulmonary oedema;

9. Hypokalemia with normal or elevated plasma renin levels in the absence of diuretic therapy;

10. A negative family history of hypertension.

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Diagnosis Renal arteriography – a „golden standard DSA – digital subtractive angiography

Captopril stimulation with measurement of PRA: exagerrated induction of reactive hyperreninemia

Captoptil renoscintigraphy: 90% sensitivity and specificity Doppler ultrasound MRI imaging Spiral CT scan

Treatment Anatomic correction: surgery, angioplasty (PTCA) Selective venous sampling for PRA (ratio affected kidney : contralateral

kidney > 1.5 indicates functional abnormality) before anatomic correction Medical treatment: ACE inhibitors, AT1 receptor antagonists particularly

effective; beta-blockers, Ca channel blockers, methyldopa.