Question

A patient asks about the differences between primary and secondary hypertension.

·     What are the differences between primary and secondary hypertension that the nurse should review with the patient?

·     What are the routine laboratory studies that the nurse can anticipate will be ordered for the patient to aid in the diagnosis of hypertension?

Answer 1

• What are the differences between primary and secondary hypertension that the nurse should review with the patient?

Hypertension

Hypertension, also known as high or raised blood pressure, is a condition in which the blood vessels have persistently raised pressure. Blood is carried from the heart to all parts of the body in the vessels. Each time the heart beats, it pumps blood into the vessels. Blood pressure is created by the force of blood pushing against the walls of blood vessels (arteries) as it is pumped by the heart. The higher the pressure, the harder the heart has to pump.

Primary hypertension.

Primary hypertension is high blood pressure that doesn’t have a known secondary cause. It’s also referred to as Essential hypertension

Blood pressure is the force of blood against your artery walls as your heart pumps blood through your body. Hypertension occurs when the force of blood is stronger than it should be normally.

Risk factors associated with Primary hypertension

Genetic factors are thought to play a role in essential hypertension. The following factors may increase your risk of developing essential hypertension:

• diet
• stress
• minimal physical activity
• being overweight

Symptoms of Primary hypertension

Most people won’t notice any symptoms of essential hypertension. They usually discover that their blood pressure is high during a regular medical checkup.

Essential hypertension can begin at any age. It most often occurs first during middle age.

How will you know if you have essential hypertension?

Blood pressure checks are the best way to screen for the condition. It’s important to understand how to take your blood pressure and read the results.

Blood pressure readings have two numbers, usually written this way: 120/80. The first number is your systolic pressure. Systolic pressure measures the force of blood against your artery walls as your heart pumps blood to the rest of your body.

The second number measures your diastolic pressure. Diastolic pressure measures the force of your blood against your artery walls between heartbeats, as the heart muscle relaxes. Learn more about systolic and diastolic pressure.

Your blood pressure readings can fluctuate up or down throughout the day. They change after exercise, during rest, when you’re in pain, and even when you’re stressed out or angry. Occasional high blood pressure readings don’t necessarily mean you have hypertension. You won’t receive a diagnosis of hypertension unless you have high blood pressure readings at least two to three different times.

Normal blood pressure vs. abnormal blood pressure

Normal blood pressure is less than 120/80 millimeters of mercury (mmHg).

Elevated blood pressure is higher than normal blood pressure, but not quite high enough to be hypertension. Elevated blood pressure is:

• systolic pressure of 120 to 129 mmHg
• diastolic pressure less than 80 mmHg

Stage 1 hypertension is:

• systolic pressure of 130 to 139 mmHg, or
• diastolic pressure of 80 to 89 mmHg

Stage 2 hypertension is:

• systolic pressure higher than 140 mmHg, or
• diastolic pressure higher than 90 mmHg

Secondary hypertension

Secondary hypertension (secondary high blood pressure) is high blood pressure that's caused by another medical condition. Secondary hypertension can be caused by conditions that affect your kidneys, arteries, heart or endocrine system. Secondary hypertension can also occur during pregnancy.

Secondary hypertension differs from the usual type of high blood pressure (primary hypertension or essential hypertension), which is often referred to simply as high blood pressure. Primary hypertension has no clear cause and is thought to be linked to genetics, poor diet, lack of exercise and obesity.

Proper treatment of secondary hypertension can often control both the underlying condition and the high blood pressure, which reduces the risk of serious complications — including heart disease, kidney failure and strokes.

Symptoms

Like primary hypertension, secondary hypertension usually has no specific signs or symptoms, even if your blood pressure has reached dangerously high levels.

If you've been diagnosed with high blood pressure, having any of these signs may mean your condition is secondary hypertension:

• High blood pressure that doesn't respond to blood pressure medications (resistant hypertension)
• Very high blood pressure — systolic blood pressure over 180 millimeters of mercury (mm Hg) or diastolic blood pressure over 120 mm Hg
• High blood pressure that no longer responds to medication that previously controlled your blood pressure
• Sudden-onset high blood pressure before age 30 or after age 55
• No family history of high blood pressure
• No obesity

When to see a doctor

If you have a condition that can cause secondary hypertension, you may need your blood pressure checked more frequently. Ask your doctor how often to have your blood pressure checked.

Causes

A number of conditions can cause secondary hypertension. Several kidney diseases may cause secondary hypertension, including:

• Diabetes complications (diabetic nephropathy). Diabetes can damage your kidneys' filtering system, which can lead to high blood pressure.
• Polycystic kidney disease. In this inherited condition, cysts in your kidneys prevent the kidneys from working normally and can raise blood pressure.
• Glomerular disease. Your kidneys filter waste and sodium using microscopic-sized filters called glomeruli that can sometimes become swollen. If the swollen glomeruli can't work normally, you may develop high blood pressure.

• Renovascular hypertension. This type of hypertension is caused by narrowing (stenosis) of one or both arteries leading to your kidneys.

Medical conditions affecting hormone levels may also cause secondary hypertension. These conditions may include:

• Cushing syndrome. In this condition, corticosteroid medications may cause secondary hypertension, or hypertension may be caused by a pituitary tumor or other factors that cause the adrenal glands to produce too much of the hormone cortisol.
• Aldosteronism. In this condition, a tumor in one or both of the adrenal glands, increased growth of normal cells in one or both of the adrenal glands or other factors cause the adrenal glands to release an excessive amount of the hormone aldosterone. This makes your kidneys retain salt and water and lose too much potassium, which raises blood pressure.
• Pheochromocytoma. This rare tumor, usually found in an adrenal gland, increases production of the hormones adrenaline and noradrenaline, which can lead to long-term high blood pressure or short-term spikes in blood pressure.
• Thyroid problems. When the thyroid gland doesn't produce enough thyroid hormone (hypothyroidism) or produces too much thyroid hormone (hyperthyroidism), high blood pressure can result.
• Hyperparathyroidism. The parathyroid glands regulate levels of calcium and phosphorus in your body. If the glands secrete too much parathyroid hormone, the amount of calcium in your blood rises — which triggers a rise in blood pressure.

Other possible causes of secondary hypertension include:

• Coarctation of the aorta. With this defect that's generally present at birth, the body's main artery (aorta) is narrowed (coarctation). This forces the heart to pump harder to get blood through the aorta and to the rest of your body. This, in turn, raises blood pressure — particularly in your arms.

• Sleep apnea. In this condition, often marked by severe snoring, breathing repeatedly stops and starts during sleep, causing you to not get enough oxygen.

  Not getting enough oxygen may damage the lining of the blood vessel walls, which may make your blood vessels less effective in regulating your blood pressure. In addition, sleep apnea causes part of the nervous system to be overactive and release certain chemicals that increase blood pressure.

• Obesity. As you gain weight, the amount of blood circulating through your body increases. This puts added pressure on your artery walls, increasing your blood pressure.

  Excess weight often is associated with an increase in heart rate and a reduction in the capacity of your blood vessels to transport blood. In addition, fat deposits can release chemicals that raise blood pressure. All of these factors can cause hypertension.

• Pregnancy. Pregnancy can make existing high blood pressure worse, or may cause high blood pressure to develop (pregnancy-induced hypertension or preeclampsia).

• Medications and supplements. Various prescription medications — such as pain relievers, birth control pills, antidepressants and drugs used after organ transplants — can cause or aggravate high blood pressure in some people.

  Over-the-counter decongestants and certain herbal supplements, including ginseng, licorice and ephedra (ma-huang), may have the same effect. Many illegal drugs, such as cocaine and methamphetamine, also increase blood pressure.

What are the routine laboratory studies that the nurse can anticipate will be ordered for the patient to aid in the diagnosis of hypertension?

Routine laboratory tests that should be performed for the investigation of all patients with hypertension include:

1. Urinalysis
2. Blood chemistry (potassium, sodium, and creatinine)
3. Fasting blood glucose and/or glycated hemoglobin (A1c)
4. Serum total cholesterol, low-density lipoprotein, high-density lipoprotein (HDL), non-HDL cholesterol, and triglycerides ; lipids may be drawn fasting or non-fasting .
5. Standard 12-lead electrocardiography .

There is little direct evidence on which to base recommendations for laboratory testing. Thus, the recommended tests have been based largely on expert opinion. However, the routine laboratory investigations are recommended for the following reasons. First, abnormalities in these tests are common. For example in the Prospective Cardiovascular Muenster (PROCAM) study, 20% of subjects with hypertension had hyperlipidemia and 10% had diabetes mellitus . Second, the screening for abnormal serum biochemistry ensures appropriate selection of drug therapy when necessary. For example, caution is warranted if diuretic therapy is considered for patients with hypokalemia or if an angiotensin-converting enzyme (ACE) inhibitor is considered for patients with elevated creatinine levels. Third, these investigations also aid in the determination of the risk of cardiovascular disease for patients with hypertension based on the presence or severity of concomitant vascular risk factors. As such, the results may shorten the diagnostic phase (if target organ damage is present), define a higher risk group or affect the choice of first-line therapy. For example, an EKG may reveal the presence of left ventricular hypertrophy (LVH) or a prior myocardial infarction, both of which portend a higher risk of future cardiovascular events and death . Finally, both the routine and optional investigations aid in the screening for some of the modifiable causes of hypertension. For example recurrent and/or severe hypokalemia may indicate the presence of primary hyperaldosteronism.

• Assess urinary albumin excretion in patients with diabetes .

Assessment of urinary albumin excretion is no longer used as a basis for targeting lower BP, but is used to guide treatment of hypertension in association with diabetes mellitus. If albuminuria is present, therapy with a renin angiotension system blocker (ACE inhibitor or angiotensin receptor antagonist) is indicated (please see relevant treatment recommendation for further details).

In patients without diabetes, urine albumin to creatinine ratio (ACR) is not recommended. Although an independent predictor of future cardiovascular events, the evidence is not considered strong enough at this time to recommend routine screening of urine albumin levels in people with hypertension who do not have diabetes.

• All treated hypertensive patients should be monitored according to the current Diabetes guidelines for the new appearance of diabetes .

Hypertensive patients are at higher risk for developing type 2 diabetes because of the tendency of cardiometabolic risk factors to cluster, particularly with central adiposity . At minimum, new-onset diabetes occurs in 1% to 2% of hypertensive patients per year and is independent of the type of antihypertensive therapy . Among 18,411 nondiabetic hypertensive patients 55 years of age or older who had follow-up measurements of fasting plasma glucose (43% of the original cohort), the cumulative incidence of diabetes was 8% to 11% at four years . Furthermore, the prognosis of patients who develop diabetes is worse than those who do not (25-29). After 14.3 years of follow-up in the placebo arm of the Systolic Hypertension in Elderly Patients (SHEP) trial (28) (age older than 60 years), there was a significant increase in the cardiovascular mortality (hazard ratio [HR] 1.56; 95% CI 1.12 to 2.18) and total mortality (HR 1.35; 95% CI 1.05 to 1.73) among those who developed diabetes.

• During the maintenance phase of hypertension management, tests (including those for electrolyte, creatinine, and fasting lipids) should be repeated with a frequency reflecting the clinical situation .

Follow-up lab testing may be indicated to monitor for adverse effects of antihypertensive treatment, as surveillance for the development of end-organ damage and/or to re-stratify cardiovascular risk. The need for such testing differs across hypertensive patients and, in the absence of specific studies to define the optimal testing frequency, is left to the judgment of individual clinicians.