Version May 2024
INTRODUCTION — The diagnosis of hypertension is typically made by comparing blood pressure (BP) with normative BP values. However, it is challenging to make the diagnosis of hypertension in infants because of the lack of robust normative data and because BP is not routinely measured in healthy infants due to technical difficulties. A high index of suspicion, based on history or physical examination, is needed to make a diagnosis of hypertension because BP measurements are not routinely performed on children less than three years of age.
The definition of hypertension based on available data, risk factors, and etiology for hypertension in infants between one month and one year of age will be reviewed here. The etiology and risk factors of hypertension in neonates, and the management of hypertension in infants are discussed separately. (See "Etiology, clinical features, and diagnosis of neonatal hypertension" and "Management of hypertension in neonates and infants".)
DEFINITION — As in older children, the definition of hypertension in infants is based upon blood pressure (BP) percentiles. The systolic and diastolic BPs are of equal importance in determining the following BP categories (see "Definition and diagnosis of hypertension in children and adolescents"):
●Normal BP – Both systolic and diastolic BP <90th percentile.
●Elevated BP – Systolic and/or diastolic BP ≥90th percentile but <95th percentile.
●Hypertension – Systolic and/or diastolic BP ≥95th percentile measured upon three or more separate occasions. In children greater than one year of age, the degree of hypertension is further delineated by the two following stages.
•Stage 1 hypertension – Systolic and/or diastolic BP between the 95th percentile and 5 mmHg above the 99th percentile.
•Stage 2 hypertension – Systolic and/or diastolic BP ≥99th percentile plus 5 mmHg.
However, depending on clinical presentation, it may not be advisable to wait for additional separate BP measurements, and intervention may be required on the basis of a single BP measurement because it is markedly elevated or there are associated symptoms or findings (eg, left ventricular hypertrophy). (See 'Diagnosis' below.)
NORMAL BLOOD PRESSURE — Data are limited on the normal BP values for infants between 1 and 12 months of age. As a result, the 2017 American Academy of Pediatrics (AAP) revised guidelines for screening and managing high blood pressure (BP) for children and adolescents continue to use reference data from the 1987 second task force by the National High Blood Pressure Education Program (NHBPEP) Working Group until more information is available (figure 1A-B) [1,2]. These data show that BP is relatively unchanged between the neonatal period and one year of age.
A reference table of normal BP values at or after two weeks of age based on postconceptual age was developed based on a review of the literature on normal neonatal BP (table 1). From these data, the 95th percentile values for systolic, diastolic, and mean BPs for infants at postconceptual age of 44 weeks (ie, one month of age for term infants) are 105, 68, and 80 mmHg, respectively.
ETIOLOGY — The causes of hypertension in infants between one month of age and one year of age are similar to those seen in patients with neonatal hypertension. In addition, many of these patients develop hypertension because of neonatal complications. (See "Etiology, clinical features, and diagnosis of neonatal hypertension" and "Etiology, clinical features, and diagnosis of neonatal hypertension", section on 'Etiology'.)
Causes of hypertension in infants beyond the neonatal period include:
●Renovascular injury due to neonatal placement of umbilical arterial catheters.
●Bronchopulmonary dysplasia.
●Kidney injury with fluid retention due to perinatal complications (eg, perinatal asphyxia). (See "Neonatal acute kidney injury: Pathogenesis, etiology, clinical presentation, and diagnosis".)
●Renal vein thrombosis. (See "Neonatal thrombosis: Clinical features and diagnosis", section on 'Renal vein thrombosis'.)
●Neurologic disorders such as intracranial hemorrhage, increased intracerebral pressure, seizures, or pain.
●Congenital kidney and urologic disorders (eg, polycystic kidney disease and renal hypoplasia/dysplasia, urinary obstruction. (See "Overview of congenital anomalies of the kidney and urinary tract (CAKUT)".)
●Endocrine disorders, such as hyperthyroidism or congenital adrenal hyperplasia, especially due to 11-hydroxylase (CYP11B1) and 17-hydroxylase (CYP17) deficiencies, which are associated with an increased production of deoxycorticosterone, hyperaldosteronism, pseudohypoaldosteronism type II. (See "Evaluation and management of neonatal Graves disease" and "Uncommon congenital adrenal hyperplasias", section on 'CYP17A1 deficiencies' and "Uncommon congenital adrenal hyperplasias", section on '11-beta-hydroxylase deficiency'.)
●Coarctation of the aorta. (See "Clinical manifestations and diagnosis of coarctation of the aorta", section on 'Neonates'.)
●Medications such as caffeine, theophylline, corticosteroids, and beta-adrenergic agents.
●Other rare causes include:
•Tumors including Wilms tumor, pheochromocytoma, neuroblastoma, and mesoblastic nephroma.
•Orthopedic procedures, particularly those requiring skeletal traction [3]. Hypertension occurs soon after the procedure, can be severe enough to cause symptoms, and resolves on discontinuation of the treatment. Hypertension may be associated with hypercalcemia, which probably plays no causative role in traction-related hypertension.
•Hypercalcemia.
•Drug withdrawal in infants of mothers with substance abuse due to heroin or cocaine.
•Exposure to marijuana – Passive exposure can result in increased BP in both children and infants. (See "Cannabis (marijuana): Acute intoxication", section on 'Clinical manifestations'.)
•Closure of abdominal wall defect.
WHEN SHOULD BLOOD PRESSURE BE MEASURED — Because the incidence of hypertension is low in children less than three years of age, routine blood pressure (BP) monitoring is not recommended unless the patient is at risk for hypertension [1].
Risk factors include the following:
●History of neonatal complications requiring neonatal intensive care
●Congenital heart disease
●Known kidney or urologic disease
●Family history of congenital kidney disease
●Solid organ or bone marrow transplantation
●Malignancy
●Treatment with drugs known to raise BP
●Other systemic illnesses associated with hypertension, such as tuberous sclerosis or neurofibromatosis
●Evidence of increased intracranial pressure
●Unexplained seizures
In particular, events during pregnancy or the neonatal period are an important risk factor for hypertension in this age group.
●Children with low birth weight, premature birth, or those who need neonatal intensive care treatment are at increased risk of developing hypertension during infancy and early childhood [4,5]. This was illustrated in a retrospective study of 650 infants discharged from neonatal intensive care units (NICUs) [5]. In this cohort, 2.6 percent had hypertension defined by systolic BP of more than 113 mmHg on three consecutive visits over a six-week period. Hypertension was diagnosed at a mean age of approximately two months post-term with correction for prematurity.
●Infants with bronchopulmonary dysplasia (BPD) compared with those without BPD are also at increased risk to develop hypertension following discharge from the NICU [6,7]. In one study of infants with birth weight less than 1250 g, the overall incidence of hypertension was 6.8 percent and was 12 percent in those with BPD [7]. The mean age of onset of hypertension was 105 days (range 90 to 133 days). The severity of hypertension correlated with the severity of the pulmonary disease.
BLOOD PRESSURE MEASUREMENT
Methodology
●Oscillometric versus manual or direct measurements ‒ When comparing blood pressure (BP) measurements, it is important to verify the method used to obtain normative data as oscillometric BP measurements are generally higher than those obtained by manual or direct methods. The data from the National High Blood Pressure Education Program (NHBPEP) Fourth Task Force Report are based on ausculatory measurements, whereas the data presented previously are obtained by oscillometric measurements. Because accurate measurement of BP by auscultation in young infants is often difficult, initial BP measurement in this age group is typically performed by oscillometric devices. If using the NHBPEP Fourth Task Force Report tables to determine the BP percentile, one needs to verify the BP by auscultation. (See "Definition and diagnosis of hypertension in children and adolescents", section on 'Oscillometric devices'.)
●Appropriately sized BP cuff ‒ Using the appropriately sized arm cuff is vital for accurate BP measurement. The appropriate size is a cuff with an inflatable bladder width that is approximately 50 percent of the arm circumference at a point midway between the olecranon and the acromion [8], and the bladder length should cover 80 to 100 percent of the circumference of the arm. If the choice is between a cuff that is too small or one that is too large, use of the larger cuff will result in less error. (See "Definition and diagnosis of hypertension in children and adolescents", section on 'Cuff size and placement'.)
●Sleeping versus awake measurement ‒ BP measured while the infant is sleeping may be lower than awake BP [9,10]. In a study in infants between the ages of five to nine weeks, the mean systolic BP was approximately 6 mmHg higher in awake infants compared with those who were asleep (96±11 versus 89±11 mmHg) [9]. Others have confirmed that BP is lower in infants who are asleep or awake and calm compared with those who are awake and fussy or crying [10].
Our approach — We use the following standard protocol to measure BP in infants who are at risk for hypertension [8];
●Blood pressure measured by oscillometric device, and if elevated, measured manually
●Infant in a quiet awake state or sleeping, while lying in a prone or supine position, we do not measure BP in a crying infant
●Use of an appropriate sized BP cuff with a width to arm circumference ratio of approximately 0.5
●Measurement performed in the right upper arm
●In infants who get agitated with arm cuff placement, our approach is to leave the infant undisturbed after cuff placement and measure BP only after the infant has calmed down
●If BP is high, four-limb BP measurement is performed
Ambulatory BP monitoring — Very little data are available on the role of ambulatory blood pressure monitoring (ABPM) in infants and young children. The successful use of ABPM in this age group has been reported in several case series [11-14].
●In a study on 97 healthy children aged 2 to 30 months (mean 13±3 months), a satisfactory BP profile was obtained in 86.6 percent of children with an average of 75 percent satisfactory BP recordings [12].
●In another study, satisfactory readings were obtained in 77 percent of 101 children three to six years old. This study also revealed that in contrast to the older children with expected night-time dipping, a second decrease during bed rest after lunch occurred in these children [13].
However, several limitations restrict the clinical usefulness of routine ABPM in infants and young children:
●One of the main purposes of ABPM is to diagnose white coat hypertension, which is believed to be clinically insignificant in this age group.
●There are no reliable normative data for children less than five years of age.
●Technical difficulties include patient intolerance of the inflating arm cuff and limited availability of the appropriate size cuff.
DIAGNOSIS — The diagnosis of hypertension is typically made by comparing blood pressure (BP) with normative BP values. However, it is challenging to make the diagnosis of hypertension in infants because of the lack of robust normative data and because BP is not routinely measured. As a result, BP measurement should be obtained in patients in whom there is a high index of suspicion for hypertension. (See 'When should blood pressure be measured' above.)
The diagnosis of childhood hypertension is made when repeat blood pressure (BP) values on three separate occasions are greater than the 95th percentile for the age, sex, and height of the patient [1]. Because there are no normative data to determine the 95th percentile for BP for infants below one year of age, normative data for one-year-old children is used to help define infantile hypertension. In addition, we diagnosis hypertension on <3 measurements for those infants with a high BP and in the presence of a risk factor or if there is associated clinical findings. (See 'Normal blood pressure' above.)
In our practice, we use the following clinical threshold to diagnosis and treat hypertension based normative data for one-year-old children from the National High Blood Pressure Education Program (NHBPEP) Task Force [15]. (See 'Normal blood pressure' above.)
●For asymptomatic infants with an oscillometric awake BP of >100/60, we confirm it by manual reading and monitor it during follow-up visits. For confirmed manually measured BP of >110/70, we start evaluation for an underlying cause of hypertension.
●Treatment is generally initiated for manually measured BP persistently ≥110/70. Treatment at lower levels is initiated if there is left ventricular hypertrophy or if the patient has a comorbid condition, such as chronic kidney disease.
EVALUATION — Once it has been determined that the infant is hypertensive, an evaluation is performed to identify the cause of hypertension, treat any curable cause, and determine the extent of target organ damage. Because the causes of hypertension in this age group are often due to perinatal events, the evaluation is similar to that performed for neonatal hypertension. (See 'Etiology' above and "Etiology, clinical features, and diagnosis of neonatal hypertension", section on 'Evaluation'.)
The assessment includes:
●History ‒ A focused history that reviews perinatal exposures (eg, maternal use of prescribed and illicit drugs, history of perinatal asphyxia), neonatal course (eg, umbilical arterial catheterization), presence or family history of congenital kidney or urinary tract anomalies, or concurrent conditions associated with hypertension (eg, bronchopulmonary dysplasia).
●Physical examination ‒ Physical examination must include four-limb blood pressure (BP) measurement and palpation of femoral pulses to rule out the possibility of coarctation of the aorta. Other findings that may explain the cause of hypertension include presence of dysmorphic features (eg, Williams syndrome), birth marks (eg, café au lait spots), ambiguous genitalia (eg, congenital adrenal hyperplasia), bulging and tense anterior fontanel, palpable kidneys, or any other abdominal masses, cardiac murmurs, heart failure (gallop rhythm and hepatomegaly), or abdominal bruit.
●Laboratory evaluation ‒ Initial laboratory evaluation includes urinalysis, complete blood count, and measurement of serum blood urea nitrogen, creatinine, electrolytes, and calcium. Further testing is guided by the initial evaluation and individualized for each patient. (See "Evaluation of hypertension in children and adolescents", section on 'Further evaluation'.)
●Additional tests
•Echocardiography is performed to determine whether there is left ventricular hypertrophy as evidence of end-organ involvement and to diagnose coarctation of the aorta, if present.
•Kidney ultrasound examination and Doppler flow study for kidney/renovascular pathology.
•Selected cases may need additional investigations such as urine catecholamines, renal angiography or serum renin, aldosterone, cortisol levels, or thyroid function tests.
SOCIETY GUIDELINE LINKS — Links to society and government-sponsored guidelines from selected countries and regions around the world are provided separately. (See "Society guideline links: Hypertension in children".)
SUMMARY AND RECOMMENDATIONS
●Definition ‒ As is true in older children, hypertension in infants is defined as either systolic or diastolic BP that is ≥95th normative BP percentile measured upon three or more separate occasions. However, hypertension is uncommon in infants, and blood pressure (BP) is not routinely measured in infants and young children beyond the neonatal period. As a result, there is limited information on normal BP in infants less than one year of age. Currently available literature suggests that normative data from one-year-old children can be used to help guide BP management in younger infants. (See 'Normal blood pressure' above and 'Definition' above.)
●Etiology ‒ The causes of hypertension in infants between one month and one year of age are similar to those seen in patients with neonatal hypertension. In addition, many of these patients develop hypertension because of neonatal complications, such as bronchopulmonary dysplasia, renovascular injury due to umbilical artery catheterization, renal vein thrombosis, and neurologic sequelae (eg, intraventricular hemorrhage). Other causes of infantile hypertension include congenital anomalies of the kidney and urinary tract (CAKUT), endocrine disorders (eg, congenital adrenal hyperplasia and hyperthyroidism), medications, and coarctation of the aorta. (See 'Etiology' above.)
●Indications for BP measurement ‒ Because the incidence of hypertension is low in children less than three years of age, routine BP monitoring is not recommended unless the patient is at risk for hypertension. Infants at risk for hypertension include those with complications that required admission to a neonatal intensive care unit, congenital heart disease, CAKUT, and other illnesses and conditions associated with hypertension. (See 'When should blood pressure be measured' above.)
●Blood pressure measurement ‒ BP measurement in infants should be performed in a standardized approach that routinely measures BP in the same extremity and position, using an appropriate size BP cuff in a quietly awake or sleeping infant. (See 'Blood pressure measurement' above.)
●Diagnosis ‒ The diagnosis of hypertension is typically made by comparing BP with normative BP values. However, it is challenging to make the diagnosis of hypertension in infants because of the lack of robust normative data and because BP is not routinely measured in healthy infants. In our practice, BP measurement is performed for infants who are at risk for elevated BP and the diagnosis of hypertension is made when repeat BP measurement on three separate occasions exceeds the 95th percentile for BP for one-year-old children. In addition, hypertension is diagnosed based on fewer BP measurements for infants with significantly elevated BP or if there are additional risk factors. We use the following BP threshold based on currently available data. (See 'Diagnosis' above.)
•For infants with an oscillometric awake BP of >100/60, management consists of confirmation with manual reading and monitor with manual BP measurements at follow-up visits. An evaluation for an underlying cause is initiated for confirmed manually measured BP of >110/70.
•Treatment is generally initiated for manually measured BP persistently ≥110/70, or sooner if patient is symptomatic or left ventricular hypertrophy is present.
●Evaluation ‒ Once it has been determined that the infant is hypertensive, an evaluation is performed to identify the cause of hypertension, treat any curable cause, and determine the extent of target organ damage. Because the causes of hypertension in this age group are often due to perinatal events, the evaluation is similar to that performed for neonatal hypertension. (See 'Evaluation' above and 'Etiology' above and "Etiology, clinical features, and diagnosis of neonatal hypertension", section on 'Evaluation'.)
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