Elevated Blood Pressure in Children

Abstract

Unhealthy dietary habits, low physical activity, harmful habits, and excess body weight are the main risk factors for elevated blood pressure (BP). Elevated BP affects 5–15% of children. According to a study conducted in Lithuania in 2009, 5.5% of children and adolescents have arterial hypertension (AH), while 1.7% have severe AH. This article presents the assessment, diagnosis, and treatment of elevated BP in children.

Epidemiology

Normal BP in children is determined by systolic and diastolic BP values relative to the 95th percentile [1–3]. The exact prevalence of elevated BP among children is unknown. However, according to various sources, it ranges from 5% to 15% across different countries and tends to increase [2–6]. On average, prehypertension is diagnosed in 2.2–3.5% of children, while approximately 3.5% have AH [7, 8]. Elevated BP is more common among boys (15–19%) than girls (7–12%) [1, 9].

In Lithuania, a study conducted in 2009 among children and adolescents aged 6–18 years found AH in 5.5% and severe AH in 1.7% [3]. Studies have shown that elevated BP during childhood is a risk factor for developing AH and metabolic syndrome in adulthood. Therefore, it is important to identify elevated BP as early as possible, monitor affected children, modify their lifestyle and habits, initiate pharmacological treatment when necessary, and appropriately reassess their condition as they grow [10–13].

Risk Factors

Risk factors for AH are divided into non-modifiable factors, such as prematurity, congenital hypotrophy, a family history of hereditary diseases, and a family history of congenital kidney diseases, and modifiable factors, including dietary habits, overweight or obesity, sleep disorders, stress, and harmful habits [1–3].

The main risk factors include diabetes, dyslipidemia, obesity, physical activity and dietary habits, smoking, alcohol consumption, low birth weight and gestational age, and a history of snoring or episodes of sleep apnea [2].

One of the most important risk factors for developing secondary AH is obesity [1, 2]. Between 1990 and 2016, the number of obese children younger than 5 years increased from 32 million to 41 million. It was estimated that this figure would reach 70 million by 2025 [14].

Obesity is diagnosed when the body mass index (BMI) exceeds the 95th percentile for age and sex, while severe obesity is defined as a BMI above the 99th percentile [6, 15–17].

Studies have shown that obese children have a 2-fold higher risk of developing AH than children of normal weight, while those with severe obesity have a 4-fold higher risk [18]. Among obese children aged 6–18 years, 27–47% also have AH [19].

Another important factor is sleep disturbance, including snoring and obstructive sleep apnea syndrome. If a child sleeps fewer than 7 hours per night, the likelihood of developing elevated BP ranges from 3.6% to 14% [20–22].

A strong association has also been observed between AH and chronic kidney disease. Approximately 50% of children with chronic kidney disease also have elevated BP [23–25].

Recommendations for Blood Pressure Measurement and Assessment

BP in children can be measured using either an automated blood pressure monitor or a sphygmomanometer and stethoscope [1].

Initially, BP is measured using an automated device. If the measured BP is at or above the 90th percentile, BP should be measured twice more using a sphygmomanometer and stethoscope, with an interval of 2–3 minutes between measurements. The average of the last 2 measurements is then calculated [2, 26–28].

BP should be measured when the child is calm and has not engaged in physical activity for 3–5 minutes before the measurement. The patient should sit upright, with both feet touching the floor and legs uncrossed [1–3].

To obtain accurate results, BP should be measured on the right arm using a cuff that covers two-thirds of the upper arm length. During the measurement, the child should remain still and avoid talking [1, 2, 29].

There is no consensus on when a family physician should first measure a child's BP, but it is recommended to begin at the age of 3 years [30]. The conditions requiring BP measurement in children younger than 3 years are listed in Table 3.

If a child has no risk factors, BP should be measured annually. In patients who are overweight or obese, have chronic kidney disease or diabetes, or take medications that may increase BP (Table 4), BP should be measured at every visit to the family physician [31].

- If the average BP measured during a routine examination is between the 90th and 95th percentiles, elevated BP is diagnosed, and non-pharmacological treatment is recommended. BP measurement should be repeated every 6 months. If prehypertension persists after 6 months, BP should be measured in the right arm, left arm, and one leg, while non-pharmacological treatment is continued. BP should be measured again after another 6 months. If BP remains elevated, 24-hour ambulatory BP monitoring and a more detailed patient evaluation are recommended [1].

- If stage 1 AH is identified during routine BP measurement, non-pharmacological treatment is recommended. BP should be remeasured after 1–2 weeks. If stage 1 AH persists, BP should be measured in both arms and one leg, non-pharmacological treatment should be continued, and BP measurements should be repeated every 3 months. If stage 1 AH persists after 3 visits to the family physician, 24-hour ambulatory BP monitoring and a more detailed evaluation are recommended. Non-pharmacological treatment should be continued, and initiation of pharmacological treatment should be considered [1].

- If stage 2 AH is identified during routine BP measurement on the right arm, BP should immediately be remeasured in both arms and one leg, and non-pharmacological treatment should be recommended. BP measurement must be repeated after 1 week, or sooner if symptoms are present. If stage 2 AH persists, 24-hour ambulatory BP monitoring is recommended, non-pharmacological treatment should be continued, and pharmacological treatment should be initiated [1].

Primary and Secondary Arterial Hypertension

Arterial hypertension (AH) is classified as primary or secondary. Primary AH predominates in the United States; however, studies conducted in other countries have shown that primary AH is uncommon among children [32–34]. Primary AH is more frequently observed in older children (≥6 years), particularly those with a positive family history and overweight or obesity [33–37].

Studies have found that diastolic blood pressure (BP) tends to increase more in secondary AH, whereas systolic BP increases more in primary AH [33, 35, 36]. Thus, secondary AH is more common in younger children, while primary AH predominates among adolescents.

The exact etiology of primary AH remains unknown, although genetic mutations are thought to play a role. To date, 25 rare genetic mutations and 53 single-nucleotide polymorphisms associated with elevated BP have been identified [38].

Early detection and monitoring of elevated BP in children are particularly important because left ventricular hypertrophy is found in as many as 10–15% of children with primary AH [39, 40].

The most common causes of secondary AH include kidney diseases, coarctation of the aorta, endocrine disorders, and medications that increase BP. Chronic kidney diseases and renovascular abnormalities are the leading causes of secondary AH. Kidney diseases are more common in younger children (

Masked Hypertension

Masked hypertension is diagnosed when BP measured in the physician's office is normal, but elevated BP is detected during 24-hour ambulatory BP monitoring.

In one study involving randomly selected children, masked hypertension was identified in 5.8–10% of participants [16, 45–48].

Growing evidence suggests that these patients have a higher risk of target-organ damage than children whose 24-hour BP measurements are normal. Children with obesity, chronic kidney disease, or coarctation of the aorta are at increased risk of masked hypertension [49].

White-Coat Hypertension

White-coat hypertension is diagnosed when BP measured in the physician's office is at or above the 95th percentile, while measurements obtained in other settings, such as at home, are normal [1, 2].

Twenty-four-hour ambulatory BP monitoring helps distinguish white-coat hypertension from primary or secondary AH [50, 51].

Studies have shown that nearly 50% of children with elevated BP measured in the physician's office actually have white-coat hypertension [52–54].

Diagnosis

To determine the cause of elevated BP, it is essential to obtain a thorough personal and family medical history, assess the child's physical condition and dietary habits, and evaluate laboratory test results [1].

- Medical history. Family conditions that may contribute to elevated BP in children include AH, diabetes, dyslipidemia, cardiovascular diseases, hereditary kidney diseases (such as polycystic kidney disease and Alport syndrome), hereditary endocrine disorders (such as adrenal tumors), and syndromes associated with AH (such as neurofibromatosis) [2]. When obtaining the patient's medical history, the assessment should begin with the perinatal period. It is important to determine whether the mother had elevated BP before or during pregnancy and whether the child was born prematurely or with low birth weight, as all these factors may influence BP in adulthood [41, 55]. The risk of AH in adulthood also increases if oligohydramnios, anoxia, renal artery or vein thrombosis, or umbilical artery catheterization occurred during the perinatal period [2].

- Diet and physical activity. Because overweight and obesity are among the most important risk factors for developing AH, it is essential to assess the child's dietary habits, including daily salt, fat, and sugar intake, whether sufficient fruits and vegetables are consumed, and whether the diet is balanced. The child's level of physical activity should also be evaluated [56–60].

- Psychosocial history. Anxiety, stress, and depression affect not only adults but also children. These problems are particularly relevant among overweight children, approximately 70% of whom experience such difficulties [61]. From the age of 11 years, children should be asked about smoking, alcohol consumption, and illicit drug use [62].

- Physical examination. Weight and height should be measured, body mass index (BMI) calculated, and BP assessed [1]. During the second physician visit, if BP remains elevated, measurements should be taken in both arms and one leg [1]. Symptoms suggesting target-organ damage include headache, nosebleeds, dizziness, visual disturbances, convulsions, seizures, dyspnea, chest pain, and syncope [2].

- Twenty-four-hour ambulatory BP monitoring. This is recommended before initiating pharmacological treatment to avoid treating white-coat hypertension with medication. It is also recommended in patients with diabetes, chronic kidney disease, target-organ damage, severe obesity with or without sleep disorders, or suspected masked hypertension [2].

- Laboratory tests. Routine laboratory investigations are performed in all children with AH. When secondary AH is suspected, plasma creatinine, urea, uric acid, electrolyte concentrations, and blood glucose are measured to help identify the underlying cause of elevated BP [1, 2].

- Echocardiography. This examination is most commonly performed to assess left ventricular size [1].

Treatment

The goal of treatment is to reduce the risk of target-organ damage, cardiovascular disease, and kidney injury [1, 2]. In children receiving treatment for AH, the target BP should be

Non-pharmacological treatment of elevated BP includes:

- Lifestyle modification. Increased consumption of fruits, vegetables, low-fat milk, whole-grain products, fish, poultry, nuts, and lean red meat is recommended, together with reduced intake of sugar, sweeteners, and salt [1, 65–69].

- Physical activity. One study found that obese children who participated in moderate-intensity aerobic physical activity for 40 minutes, 3–5 times per week, experienced an average reduction in systolic BP of 6.6 mmHg. Another study found that after 3 months of increased physical activity, systolic BP decreased by 7–12 mmHg and diastolic BP by 2–7 mmHg [2, 58].

- Weight reduction.

- Stress reduction. A study conducted in Massachusetts observed a beneficial effect of combining breathing exercises and meditation on elevated BP. Systolic BP decreased by an average of 3–4 mmHg, while diastolic BP decreased by 1 mmHg [70].

When each non-pharmacological treatment recommendation is considered individually, the beneficial effect is relatively modest. However, implementing all recommendations together may produce substantial improvements in BP reduction among patients with primary AH.

Angiotensin-converting enzyme inhibitors (ACE inhibitors), adrenergic blockers, long-acting calcium channel blockers, and thiazide diuretics are the main medications used to treat AH in children [1, 71]. Preference is given to medications administered once daily [2].

Treatment begins with monotherapy, using the lowest recommended dose. The dose is then gradually increased until BP becomes

After pharmacological treatment has been initiated, the patient should attend follow-up appointments every 4–6 weeks until BP is

Meda Sutkevičiūtė

Vilnius University Hospital Santaros Klinikos

Source: Pediatrija, No. 2, 2018.