Scope of the problem

Hypertension is one of the most common chronic diseases in the United States, affecting approximately 30% of adults and uncontrolled in more than half of those with hypertension.[1] Rates are nearly equal between genders with 31.3% of men aged 20 and older affected compared with 29.6% of women. However, this is not the same across all age ranges. Men have higher rates of hypertension than age-matched premenopausal women. Between ages 45 and 64, the rates are similar in men and women. At 65 and older, women have higher rates of hypertension than men.[2] Up to 75% of American women older than 60 have hypertension.[3] For both genders, African-American people are affected more often than whites and prevalence increases with increasing age.

A National Health and Nutrition Examination Survey (NHANES) study of women aged 20–49 found that over a 10-year period, the proportion of women diagnosed with hypertension remained stable, although the proportion of women who were advised to start antihypertensive therapy and the number of women who reported compliance with an antihypertensive drug regimen showed a statistically significant increase, possibly reflecting increased attention to hypertension over time.[4]

Hypertension is associated with serious cardiovascular disease including stroke, myocardial infarction, and congestive heart failure as well as kidney disease and retinopathy.[5, 6] Although hypertension is often found in women with other risk factors (e.g., diabetes mellitus or dyslipidemia), elevated blood pressure is an independent risk factor for cardiovascular and renal disease, and the risk increases with rising blood pressure levels.[5] Cardiovascular disease is the leading cause of death among American women, and hypertension accounts for approximately 41% of the attributable risk, surpassing tobacco use and physical inactivity. The Women’s Health Initiative study identified hypertension as a major independent risk factor for sudden cardiac death; sudden cardiac death is most common in postmenopausal women.[6]

Definition

Normal blood pressure is a systolic blood pressure (SBP) of <120 mmHg and a diastolic blood pressure (DBP) of <80 mmHg. Prehypertension is SBP 120 mm Hg–139 mmHg or DBP 80 mmHg–89 mmHg. Hypertension in adults (aged 18 and older) is defined as a systolic blood pressure equal to or greater than 140 mmHg or a diastolic blood pressure equal to or greater than 90 mmHg.[7, 8] It is further divided into stage 1 hypertension (SBP 140 mmHg–159 mmHg or DBP 90 mmHg–99 mmHg) and stage 2 hypertension (SBP ≥160 mmHg or DBP ≥100 mmHg).[5] Despite these definitions, it is important to remember that blood pressure and its association with cardiovascular risk is on a continuum. The definition of hypertension is based on the number at which treatment reduces risk.[8]

Hypertension can be primary (e.g., essential hypertension) or secondary (e.g., caused by other conditions). Although the majority of people have essential hypertension, the diagnosis of secondary hypertension is important for determining treatment and reducing future risk. Other types of hypertension include masked hypertension, pseudohypertension, resistant hypertension, and white-coat hypertension.

Risk factors

The etiology of essential hypertension is unknown, but many theories exist, including some specific to the development of hypertension in women. Independent risk factors for developing hypertension include obesity, age, ethnicity, diabetes mellitus, and chronic kidney disease.[12] Family history of hypertension, particularly early-onset is a risk factor for developing hypertension.[8] There are a number of established risk factors and conditions known to cause secondary hypertension. These include chronic kidney disease, coarctation of the aorta, Cushing’s syndrome, obstructive sleep apnea, pheochromocytoma, primary aldosteronism, renovascular hypertension, and thyroid or parathyroid disease.[5]

Lifestyle factors that increase risk for developing hypertension include obesity, which may be the most significant modifiable risk factor.[12] Dietary factors linked to developing hypertension include total grain intake, salt consumption, ingestion of processed (compared to unprocessed) red meat, and low levels of fruit intake in nonobese women.[12–15] Recreational (as opposed to occupational) physical activity is inversely related to risk of hypertension.[16] Women getting five or fewer hours of sleep demonstrated increased risk of hypertension in the Nurses’ Health Study.[17]

Vitamin D insufficiency may be a predictor of future risk of systolic hypertension.[18] Women with osteoporosis are significantly more likely to have hypertension; both diseases are associated with decreased dairy intake.[19]

Certain risk factors may be gender specific or influenced by gender. For example, women exposed to famine while in utero demonstrate an increased blood pressure measurement and were significantly more likely to have been diagnosed with and treated for hypertension than women who were not exposed to famine. The same relationship was not seen in male counterparts.[20] Although obesity significantly increases the risk of both hypertension and prehypertension in women and men, the magnitude of increased risk is greater in women.[21] Preeclampsia quadruples future risk of hypertension.[2, 8]

Diagnosis

In order to diagnose hypertension, the blood pressure must be obtained correctly. In the office, the sphygmomanometer is used; it should be calibrated periodically. Measurement is taken from the upper arm using an appropriately sized cuff, defined as the cuff bladder encircling at least 80% of the upper arm.[5] The patient should be seated for five minutes quietly prior to measurement. Measurement should be obtained while the patient is seated with the back supported and the feet on the floor while the arm is supported at heart level.[5] The blood pressure should be taken twice about one to two minutes apart and repeated if there is a significant difference. Since blood pressure may be significantly different between the left and right arm, on an initial visit, it is important to obtain both measurements, using the higher reading as the reference blood pressure. A difference in blood pressure between arms of more than 10 mmHg is associated with increased cardiovascular risk.[8] The first Korotkoff sound is the systolic blood pressure and the fifth (disappearance) sound is the diastolic.

There are common pitfalls to accurate measurement.[8] Clinicians may be susceptible to two types of error in recording the blood pressure measurement. The first is rounding bias in which the blood pressure is rounded up or down. The second is digit bias in which the number is recorded at a specific digit, for example at a number ending in a zero (e.g., 120, 130). The auscultatory gap, which is more common in elderly patients, refers to the disappearance of Korotkoff sounds as the cuff is being deflated, which then reappear at a lower pressure. The second set of sounds can be mistaken for the systolic blood pressure. Elderly patients are also at increased risk of manifesting pseudohypertension in which the pressure measured by the cuff exceeds the actual intra-arterial pressure because of vascular stiffness.[10]

History

Ask patients with hypertension about the length of diagnosis, previous blood pressure values (including home readings), and any history of antihypertensive therapy.[8] Many patients with hypertension have or are at risk for other cardiovascular disease, so a history of stroke or TIA, myocardial infarction, valvular heart disease, congestive heart failure, peripheral artery disease, kidney disease, and diabetes should be elicited. Specific to women, a history of gestational HTN, eclampsia or preeclampsia, and polycystic ovarian syndrome (PCOS) are associated with increased prevalence of hypertension.[8, 22]

It is important to carefully elicit any associated signs or symptoms that may be related to hypertension in order to identify comorbid conditions, causes of secondary hypertension, and presence of end-organ damage. Many patients with hypertension report no symptoms relatable to elevated blood pressure. Elevated blood pressure, however, can be associated with symptoms of end-organ damage or with symptoms that suggest a secondary cause of hypertension (i.e., hyperthyroidism, primary aldosteronism). Therefore, a complete review of systems should be elicited focusing on neurologic symptoms, symptoms of renal disease, cardiovascular symptoms, endocrinologic symptoms, any cognitive deficit, and history of snoring, apnea, or daytime somnolence that may suggest obstructive sleep apnea.[8]

Blood pressure is affected by a number of prescription and over-the-counter medications and supplements, so a careful history must elicit all substances that a woman is currently taking (Box 42-1). Oral contraceptive pills are a common medication taken by women and are associated with both elevated systolic and diastolic blood pressure as well as increased risk for prehypertension and hypertension when used for longer than 24 months.[23]

Women should be asked about tobacco, alcohol and illicit drug use as all three of these substances can result in elevated blood pressure. Furthermore, smoking cessation, reduction of alcohol intake, and avoidance of illicit substances are important components of hypertension treatment. Eliciting information about lifestyle including diet and physical activity may reveal opportunities for intervention.[8]

Understanding family history is important in the evaluation of a woman with hypertension. Patients should be asked about family history of hypertension and cardiovascular disease, especially an early onset of either condition. Additionally, it is important to elicit any history of diabetes, dyslipidemia, or chronic kidney disease (looking for polycystic kidney disease).[8]

Physical examination

The physical examination of a patient with elevated blood pressure starts with the appropriate measurement of blood pressure. Height, weight, body mass index (BMI), and waist circumference should be measured. The examination should include auscultation of the heart; the presence of a heart murmur may warrant further investigation. The pulse at rest should be obtained; both tachycardia and arrhythmia should prompt additional testing. A careful examination should be made of the neck for thyroid disorders, the neurologic system, vascular system including auscultation of the carotid and renal arteries and palpation of peripheral pulses, and the abdomen for enlarged kidneys (associated with polycystic kidney disease). A fundoscopic examination can detect retinal hemorrhages and a skin examination may reveal sequelae of conditions associated with secondary hypertension (i.e., Cushing’s syndrome or pheochromocytoma).[8]

It is important to consider potential causes of secondary hypertension, particularly in younger women. Women younger than age 40 with moderate to severe hypertension should be evaluated for renovascular hypertension related to fibromuscular dysplasia as this is significantly more common in women.[24] Pheochromocytoma should also be considered in younger women with characteristic symptoms. Both renovascular hypertension and pheochromocytoma are associated with pregnancy complications if untreated.[24]

Labs/diagnostic evaluation

The role of laboratory and other diagnostic testing has three goals: to identify causes of secondary hypertension, the presence of end-organ damage, and the presence of other cardiovascular disease.[8] Initial testing includes creatinine [and estimation of glomerular filtration rate (GFR)], fasting blood glucose, hemoglobin and hematocrit, lipids, potassium, sodium, uric acid, urinalysis, and a 12-lead electrocardiogram.[8] Additional testing, based on the history, physical examination, and results of initial testing may include abdominal ultrasound, ankle brachial index, carotid ultrasound, echocardiogram, hemoglobin A1c, Holter monitor, peripheral artery ultrasound, quantitative urine protein, and urine electrolytes.[8]

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