What Are the Causes of Secondary Hypertension?

Secondary hypertension is hypertension with a clear etiology. When the cause is detected and the cause is effectively removed or controlled, hypertension as a secondary symptom can be cured or significantly relieved; secondary hypertension accounts for 5% of people with hypertension. % To 10%; common diseases due to renal parenchyma, renal vascular hypertension, endocrine and sleep apnea syndrome, etc., high blood pressure caused by mental and psychological problems are often seen. Patients with secondary hypertension are at higher risk for cardiovascular disease, stroke, and renal insufficiency, and the cause is often overlooked and delays diagnosis. Improving the understanding of secondary hypertension, identifying the cause in time, and actively treating the cause will greatly reduce the high mortality and disability caused by hypertension and complications. In recent years, the identification of secondary hypertension has become an important aspect of hypertension diagnosis and treatment.

Basic Information

English name

secondaryhypertension

Visiting department

Internal Medicine, Cardiovascular

Common locations

kidney

Common symptoms

Vascular disease, stroke, renal insufficiency

Causes of secondary hypertension

Renal

(1) Renal parenchymal hypertension is one of the most common secondary hypertension due to primary or secondary renal parenchymal disease. Its elevated blood pressure is often refractory and is the main cause of adolescents with hypertension emergency ; Common renal parenchymal diseases include acute and chronic glomerulonephritis, polycystic kidney disease; chronic renal tubular-interstitial disease (chronic pyelonephritis, obstructive kidney disease); renal impairment of metabolic diseases (gout nephropathy, diabetic nephropathy) ; Systemic or connective tissue disease kidney damage (lupus nephritis, scleroderma); kidney tumors (reninoma), etc.

(2) Vascular hypertension-renal artery stenosis Renal artery trunk or branch stenosis leads to renal ischemia, and the activity of the renin-angiotensin system is significantly increased, causing hypertension and renal failure. Renal artery stenosis is one of the important causes of hypertension and / or renal insufficiency, and the prevalence rate accounts for 1% to 3% of people with hypertension. At present, atherosclerosis is the most common cause of renal artery stenosis in China. It is estimated to be about 70%, followed by Takayasuitis (about 25%) and fibromuscular dysplasia (about 5%).

Endocrine

(1) Primary hyperaldosteronism (orthoaldosteronism) is a clinical syndrome in which water and sodium retention, hypertension, hypokalemia, and plasma renin activity are inhibited due to the adrenal gland's autonomous secretion of excessive aldosterone. Common causes are Adrenal adenoma, unilateral or bilateral adrenal hyperplasia, rare causes are adenocarcinoma and glucocorticoid-regulated aldosteronism (GRA).

(2) Pheochromocytoma can originate in adrenal medulla, sympathetic ganglia, or other parts of pheochromocytoma. Due to excessive secretion of catecholamines, it causes persistent or paroxysmal hypertension and multiple organ functions and metabolic disorders.

(3) Cushing syndrome is Cortisol. Its main causes are divided into two categories: ACTH-dependent or independent Cushing syndrome; the former includes pituitary ACTH tumors or ACTH cell proliferation (that is, Cushing's disease), secretion ACTH's pituitary tumors (ie, ectopic ACTH syndrome); the latter include adrenal adenomas, adenocarcinomas, or large nodular hyperplasia that autonomously secrete cortisol.

(4) Acromegaly is caused by pituitary tumors caused by excessive secretion of growth hormone from the anterior lobe, resulting in retention of water and sodium, causing an increase in blood pressure.

3. Other

(1) Aortic constriction is a rare disease, including congenital aortic constriction and acquired aortic stenosis. Congenital aortic constriction manifests as localized stenosis or atresia of the aorta. The site of the disease is usually near the opening of the aortic duct in the aortic isthmus, and it can occur elsewhere in the aorta; , Aortic stenosis caused by atherosclerosis and aortic dissection. Aortic stenosis can only cause clinically dominant hypertension in the aortic arch, descending aorta, and upper abdominal aorta. Hypertension caused by ascending aortic stenosis is difficult to detect in clinical routine blood pressure measurement, and the renal artery opening is distal Abdominal aortic stenosis generally does not cause hypertension.

(2) Obstructive sleep apnea-hypopnea syndrome refers to obstruction of the airway due to collapse of the pharyngeal muscles during sleep, recurrent apnea, or a significant decrease in oral and nasal air flow, which is one of the important causes of refractory hypertension.

(3) Polycythemia vera is a myeloproliferative disease mainly due to the abnormal proliferation of red blood cells due to unknown reasons.

(4) Drug-induced hypertension is the increase in blood pressure caused by the regular dose of the drug itself or the interaction between the drug and other drugs. Drug-induced hypertension is considered when the blood pressure is> 140 / 90mmHg.

(5) Single-gene hereditary diseases such as glucocorticoid curable aldosteronism, Liddle syndrome, Gordon syndrome, multiple endocrine tumors, etc.

Clinical manifestations of secondary hypertension

Renal

(1) Renal parenchymal hypertension Nephropathy often precedes or occurs simultaneously with hypertension; high blood pressure levels are difficult to control and easily progress to malignant hypertension; proteinuria / hematuria occurs early, severely, and renal function The damage is obvious.

(2) Renal artery stenosis Malignant or refractory hypertension; The original well-controlled hypertension was out of control; Hypertension with abdominal vascular murmur; Evidence of hypertension with vascular occlusion (coronary heart disease, cervical vascular murmur, peripheral Vascular disease); elevated serum creatinine that cannot be explained for other reasons; angiotensin-converting enzyme inhibitor or angiotensin II receptor antagonist has a very large blood pressure reduction or induces acute renal insufficiency; and left heart failure Matching paroxysmal pulmonary edema; hypertension and asymmetric kidney size.

Endocrine

(1) Protoaldehyde symptoms clinical manifestations are: nocturia, lower limb weakness or periodic paralysis, accompanied by persistent or diuretic hypokalemia (blood potassium <3.5mmol // L), accidental adrenal tumors, etc.

(2) Pheochromocytoma The typical triad of pheochromocytoma, that is, paroxysmal "headache, sweating, and palpitations", can cause severe heart, brain, and renal vascular damage; large amounts of catecholamines enter the blood and cause hypertension crisis , Hypotension shock and severe arrhythmia and other "pheochromocytoma crisis".

(3) Cushing's syndrome manifestations: concentric obesity, buffalo back, and supraclavicular fat pads; full moon face, multiple blood quality; thin skin, bruising, large purple stripes, muscle atrophy; hypertension, hypokalemia, Alkalosis; impaired glucose tolerance or diabetes; osteoporosis, or pathological fractures, urinary stones; sexual dysfunction, male impotence, female menstrual disorders, hairy, infertility, etc; children's growth and development retardation; Sacral nerve and mental symptoms; is susceptible to infection and decreased body resistance.

(4) Acromegaly is manifested by a low forehead, a wide mandible, a large protrusion, large limbs, osteoporosis, thickened skin, sweating, excessive skin oil, and persistent headache.

3. Other

(1) Aortic constriction is mainly manifested in upper extremity hypertension, and the lower limbs have weak or no veins. The blood pressure in both lower limbs is significantly lower than that in the upper limbs (ABI <0.9), and there are obvious murmurs around auscultated narrow vessels.

(2) Obstructive sleep apnea-hypopnea syndrome is mainly manifested as sleep snoring and frequent occurrence of apnea.

(3) True erythrocytosis The clinical manifestations are long and mild, the skin and mucous membranes are dark red, thrombosis or phlebitis, weight loss, bleeding gums, peptic ulcer bleeding, gout, splenomegaly, etc.

(4 ) Drug-induced increase in blood pressure is related to taking certain drugs, mainly including: hormone drugs; central nervous system drugs; nonsteroidal anti-inflammatory drugs; Chinese herbal medicine.

(5) Single-gene hereditary diseases have different clinical manifestations, see related entries for details.

Secondary hypertension test

Those with high suspicion based on medical history and physical examination were confirmed by experimental examination.

1. Renal parenchymal and renal vascular hypertension

Laboratory tests include: blood and urine routines; blood electrolytes (sodium, potassium, chlorine), creatinine, uric acid, blood glucose, blood lipids; 24-hour urine protein quantification or urinary albumin / creatinine ratio (ACR), 12-hour urine sediment examination, If proteinuria, hematuria, and urinary leukocytes are found, further urinary bacterial culture, urinary protein electrophoresis, and urinary phase contrast microscopy should be performed to determine the source of urinary protein, red blood cells, and exclude infection; renal B-ultrasound: understand the size, shape, and appearance of the kidney No tumor; if abnormal volume and morphology of the kidney or tumor is found, further renal artery CTA / MRA is needed to confirm the diagnosis and investigate the cause; fundus examination; renal puncture and pathological examination are available in a conditional hospital.

2. Endocrine hypertension

Plasma aldosterone and renin activity measurement and ratio (ARR), saline test, captopril test, adrenal vein blood hormone measurement; blood, catecholamine, adrenal gland CT, blood cortisol circadian rhythm, large and small dose dexamethasone Test, insulin-like growth factor measurement, OGTT simultaneous measurement of blood glucose and growth hormone.

3. Aortic constriction

Non-invasive examinations such as Doppler ultrasound, magnetic resonance angiography, and computed tomography angiography can determine the location and extent of stenosis. It is generally believed that if the diameter of the lesion is narrower than 50% and the systolic pressure difference between the distal and proximal lesions is greater than or equal to 20 mmHg, it has functional significance in hemodynamics.

4. Obstructive sleep apnea hypopnea syndrome

Polysomnography is the "gold standard" for diagnosing OSAHS. The diagnostic criterion is that during 7 hours of sleep each night, apnea and hypoventilation are repeated more than 30 times and / or the apnea hypopnea index is 5 times / hour; apnea refers to the stop of oral and nasal airflow for more than 10 seconds; hypoventilation Refers to a decrease in respiratory airflow to less than 50% of the basal value with a decrease in blood oxygen saturation of more than 4%.

5. Polycythemia vera

Hematology is characterized by an absolute increase in red blood cells and whole blood volume (Hb: male> 17.5g / dL, female> 16.0g / dL, RBC: male> 6.5 million / mm, female> 6 million / mm), hematocrit (male > 55%, female> 50%), arterial oxygen saturation is normal (> 92%), blood viscosity , often with leukocytes> 12000 / mm and platelets> 300,000 / mm, bone marrow hyperplasia with megakaryocyte hyperplasia.

6. Drug-induced hypertension

When asking for medical history, pay attention to asking if you have taken any medicine that raises blood pressure.

7. Single-gene hereditary diseases

Can be confirmed by genetic diagnosis.

Treatment of secondary hypertension

In principle, the treatment is mainly directed at the cause:

Renal parenchymal hypertension

Renal parenchymal hypertension should be a low-salt diet (<6g per day); large amounts of proteinuria and renal insufficiency should choose to consume high biovalent protein and limit it to 0.3 0.6g / kg / d; At the same time of effective treatment, actively control blood pressure at <130 / 80mmHg, patients with proteinuria should choose ACEI or ARB as antihypertensive drugs; long-acting calcium channel blockers, diuretics, -blockers, receptors Body blockers can be used as a combination therapy; if the glomerular filtration rate is <30ml / min or there is a large amount of proteinuria, thiazide diuretics are ineffective, and should be treated with diuretics.

2. Renal artery stenosis and aortic constriction

Can take stenotic balloon dilatation, stent placement to improve blood pressure dynamics abnormalities in stenosis to achieve the purpose of lowering blood pressure.

3. Endocrine hypertension

Most of them are benign. Surgical removal of the tumor is the most effective treatment method, but there is a certain risk of surgery, and sufficient preparations must be made before surgery. Spironolactone can be used to control the hypertension and hypokalemia of primary aldosteronism and improve Clinical symptoms; -adrenergic blockers and / or -adrenergic blockers can be used to control blood pressure, tachycardia, heart rhythm disorders, etc. of pheochromocytoma.

4. Obstructive sleep apnea hypopnea syndrome

Weight reduction and improvement of lifestyle are important for OSAHS. Oral appliances are effective for mild and moderate OSAHS; CPAP is often required for moderate and severe OSAHS; pay attention to the selection of appropriate antihypertensive drugs; for anatomy of nose, pharynx, palate and jaw Patients with abnormalities may consider corresponding surgical treatment.

5. Polycythemia vera

Antihypertensive drugs can be converted to enzyme inhibitors (ACEI), which reduce the erythrocyte enzyme activity and thus reduce Hb. Other choices include calcium antagonists such as nimodipine, indapamide (Supaphan) or central alpha ₂ stimulant clonidine, etc., and hematopoietic inhibitors such as hydroxyurea, cyclophosphamide, etc., with an effective rate of 80 ~ 85%. If necessary, cooperate with venous bloodletting, once every 1-3 days, 300-500ml each time.

6. Drug-induced hypertension

Once the diagnosis of hypertension is related to medication, these drugs should be discontinued and replaced with other drugs or treated with antihypertensive drugs.

7. Genetic hereditary diseases

See related entries for details.

Secondary hypertension prevention

Most secondary hypertension has no effective preventive measures. Early detection of hypertension and active identification of the cause are the key to avoiding serious complications of target organs of the heart, brain and kidney. Patients with a family history of hereditary diseases need genetic screening.