Evaluation of hypertension

Definitions

Hemodynamic terminology

Systolic blood pressure (SBP)

The pressure in the arteries immediately after the left heart has contracted (systole) and ejected blood out into the arteries

• Patients may refer to this number as the “top number” or “first number”

Diastolic blood pressure (DBP)

The pressure exerted by the blood against the artery walls while the heart is relaxed and the ventricles are filling with blood

• Patients may refer to this number as the “bottom number” or “second number”

Hypertension

🤏 Elevated blood pressure

• Ages 1 to <13: SBP and DBP both ≥90th percentile but <95th percentile
  • If the 90th percentile is >120 for SBP or >80 DBP, then use ≥120 or ≥80 for the respective cutoffs instead of the 90th percentile
• Ages ≥13: SBP 120-129 and DBP <80

☝️ Stage 1 hypertension

• Ages 1 to <13: SBP and/or DBP ≥95th percentile but <12 mmHg above the 95th percentile
  • If the 95th percentile is >130 for SBP or >80 for DBP, then use ≥130 or ≥80 for the respective SBP/DBP cutoffs instead of the 95th percentile
  • If the 95th percentile + 12 mmHg is >139 for SBP or >89 for DBP, then use ≤139 or ≥89 for the respective SBP/DBP cutoffs instead of 12 mmHg above the 95th percentile
• Ages ≥13: SBP 130-139 and/or DBP 80-89

✌️ Stage 2 hypertension

• Ages 1 to <13: SBP and/or DBP ≥12 mmHg above the 95th percentile
  • If the 95th percentile + 12 mmHg is >140 for SBP or >90 for DBP, then use ≥140 or ≥90 as the respective cutoffs
• Ages ≥13: SBP ≥140 and/or DBP ≥90

1️⃣ Primary hypertension

Hypertension (as defined above) that is not attributable to a medical condition

• Formerly known as “essential” hypertension
• Diagnosis of exclusion

2️⃣ Secondary hypertension

Hypertension (as defined above) for which an underlying cause can be identified

Crisis (urgency/emergency)

Hypertensive crisis

An episode of severely elevated blood pressure with the potential for end-organ damage, although no cutoff is specified. Typically, this is subcategorized as either “urgency” (severe asymptomatic hypertension) or “emergency.” May be chronic, acute, or acute-on-chronic.

Hypertensive urgency (severe asymptomatic hypertension)

Severely elevated BP without evidence of end-organ damage (e.g., symptoms, laboratory abnormalities)

• Depending on how reliable the BP measurement is, you may send these kids to ER as well. They may not get admitted if BPs can be controlled, but often admission is needed to get patients/families set up with a home BP cuff and instructions on how to measure blood pressure, initiate medications, and complete an initial workup.

Hypertensive emergency

Severely elevated BP with evidence of end-organ damage, including symptoms (e.g., dizziness, headache, vision changes, chest pain, shortness of breath, altered mentation, bleeding, etc.)

Technique

Principles of good technique

• Ensure the cuff is correctly sized, placed on the upper extremity, the patient is calm, and the measurement is repeated if elevated
• 📏 Correctly sized
  • Measure the mid upper arm circumference (MUAC) to ensure that an appropriately sized cuff is used (cuffs should be labeled with the appropriate circumference ranges)
    • The MUAC is at the midpoint between the olecranon and acromion
  • The bladder of the cuff (i.e., just the part fills with air, not the entire wrap) should encircle 80%-100% of the upper arm circumference
  • The width should be 40% of the MUAC
  • Using an inappropriately small cuff can cause spuriously high BPs, while an inappropriately large cuff may result in spuriously low BPs
• 💪 Upper extremity
  • Right arm is typically preferred for consistency and because of the possibility of coarctation (which can result in falsely low BPs in the left arm)
  • The arm should be supported and the arm should be at heart level
  • The arm should be bare above the cuff; do not place the cuff over clothing
• 🧘 Calm
  • Rested for at least 5 minutes in a quiet room while in a seated position with back supported and feet flat on the floor
    • Bear in mind that watching videos or playing video games can certainly raise some kids’ blood pressures
    • Sometimes resting for longer than 5 minutes is necessary, in which cases repeating at the end of the office visit may be helpful
  • 🤫 The room should be quiet (including talking) while the measurement is being taken
• 🔁 Repeated
  • If the first measurement is >90th percentile, repeat it twice (at least 1 minute apart) and average these two measurements:
    • If an oscillometric (“automatic”) technique was used, the measurement is still elevated (>90th percentile) on repeat, and the child is old/calm enough to cooperate, then repeat the measurement twice using the auscultatory (“manual”) technique and average these two measurements to get your final BP

🩺 Auscultatory (“manual”) method

• Place the bell of the stethoscope (not the diaphragm) over the brachial artery in the antecubital fossa, 2-3 cm below the cuff
• Inflate the cuff 20-30 mmHg above the point at which the Korotkoff sounds disappear (or the estimated systolic value)
• Deflate at a rate of 2-3 mmHg per second
• SBP = the first point at which sounds are heard (phase I Korotkoff)
• DBP = the point at which sounds are no longer audible (phase 5 Korotkoff)
  • Rarely, the sounds are audible all the way to 0 mmHg; in that case, use the point at which the sound becomes muffled (phase 4 Korotkoff)

🦵 Leg BP measurements

• Use an appropriately sized cuff placed at the midthigh
• For auscultation, place the bell of the stethoscope over the popliteal artery

🚫 Wrist/forearm measurements

• Not recommended for diagnosis or for home BP monitoring
  • Very little data in children, and there is more variability in measurements than in adults (particularly with diastolic measurements)
• Wrist BPs may be an option if the patient’s body habitus precludes upper arm BPs, though this is rare
  • No normative data exist for wrist BPs in children; use standard norms

Outpatient screening

Why screen?

• Hypertensive kids are likely to go on to become hypertensive adults
  • Clinical trials in adults show that treatment of HTN reduces risk of cardiovascular morbidity and mortality
• Identify any treatable conditions that can cause/contribute to hypertension
• Identify patients who would benefit from antihypertensive drug therapy

Who should be screened?

Office setting

• <3 years of age: patients with risk factors for hypertension should be screened annually at routine health supervision visits (well child checks)
• Patients <3 years of age without risk factors do not need routine screening for hypertension
• ≥3 years of age: all patients regardless of risk factors should be screened annually at routine health supervision visits (well child checks)
  • If patients ≥3 years have risk factors for hypertension, they should be screened at all healthcare encounters, not just routine checkups

Ambulatory blood pressure monitor (ABPM) screening

• Patients with elevated BP (defined above) for ≥1 year
• Patients with stage 1 HTN for ≥3 clinic visits
• Patients with certain high-risk conditions
• Patients with hypertension who are on antihypertensive therapy
• Typically performed by a pediatric nephrologist

A stepwise approach to evaluation of outpatient (ambulatory) hypertension

1. Ensure there is no concern for hypertensive emergency
2. Identify risk factors for primary and secondary hypertension
3. Confirm the patient has persistent hypertension
4. Proceed with a basic laboratory and imaging evaluation

1. Evaluate for hypertensive emergency

• Symptoms that can suggest end-organ damage:
  • Headache, seizures, changes in mental status (confusion, lethargy, coma), irritability (in infants), vomiting, focal neurologic complaints (facial nerve palsy, hemiplegia), visual disturbances, left-heart failure symptoms including chest pain, palpitations, cough, shortness of breath
• Even if hypertensive emergency is not suspected, it is useful to document a thorough review of these “red flag” symptoms to use as a baseline for comparison in the future

2. Identify risk factors for primary and secondary hypertension

Primary hypertension

• More likely in patients who are postpubertal
• More likely in patients who have elevated BMI (overweight/obesity)
• More common in patients of African American descent
• Often have a family history of primary hypertension
• Patients with primary hypertension are typically asymptomatic
• Patients may be predisposed to high blood pressure based on elevated BMI, diet, and/or family history of hypertension

Secondary hypertension

• More likely in young children (especially <6 years of age)
• More likely to cause diastolic hypertension
• More likely to cause nocturnal hypertension
• More likely to cause severe hypertension
• May have a family history of secondary hypertension (e.g., ADPKD)
• May have symptoms related to underlying disease
  • E.g., pheochromocytoma (paroxysms of headache, sweating, tachycardia)

Pertinent review of systems (and associated diseases)

• General:
  • fatigue (intracranial hypertension, obstructive sleep apnea [OSA])
  • hyperactivity (OSA)
  • anxiety; may also ask if they become anxious with doctor’s appointments
  • pregnancy (preeclampsia)
• Skin:
  • rash (vasculitis, systemic lupus, thyroid dysfunction)
  • sweating (thyroid dysfunction)
  • pallor (thyroid dysfunction, anemia of CKD, sickle cell anemia)
  • recent impetigo (postinfectious glomerulonephritis [GN])
  • paroxysms of pallor, flushing, diaphoresis (pheochromocytoma [PCC])
• Head: headaches, seizures (intracranial hypertension)
• Eyes: visual disturbances
• Ears: hearing loss (Alport syndrome, lead poisoning)
• Throat: recent pharyngitis (postinfectious GN)
• Respiratory: snoring, apnea (obstructive sleep apnea [OSA])
• Cardiovascular:
  • palpitations, irregular heartbeat (PCC, neuroblastoma, heart disease)
  • chest pain, exertional dyspnea (heart disease)
  • edema (heart failure, GN, CKD)
• Gastrointestinal:
  • vomiting, especially in the morning or after naps (intracranial hypertension)
  • bloody stools (hemolytic uremic syndrome [HUS])
• Genitourinary:
  • hematuria, cola-colored urine, flank pain, flank/abdominal pain, dysuria, increased urinary urgency, increased urinary frequency (CKD, AKI, UTI, GN)
• Musculoskeletal:
  • joint swelling (systemic lupus, vasculitis)

Other pertinent items in the history

• Medications: sympathomimetics (stimulants like amphetamines, methylphenidate), oral contraceptives, corticosteroids, NSAIDs, tricyclic antidepressants, calcineurin inhibitors (cyclosporine, tacrolimus)
• Medical history:
  • recurrent UTI or episodes of unexplained fever (hydronephrosis, vesicoureteral reflux [VUR])
  • abdominal trauma (direct trauma to kidney/urinary system)
  • recent head trauma, seizures (intracranial hypertension)
  • anxiety
  • perinatal complications:
    • need for umbilical artery catheter (renal artery stenosis [RAS])
    • prematurity, especially if <32 weeks (↑↑ risk w/ ↓ gestational age), had severe AKI, or received indomethacin (CKD, primary hypertension) [PMID 35853728]
    • oligohydramnios (CAKUT)
    • perinatal anoxia (CKD)
  • other conditions associated with increased risk of cardiovascular disease: obesity, diabetes (type 1 or type 2), dyslipidemia, CKD, organ transplantation, cardiac disease (including repaired coarctation), cancer, Kawasaki disease, autoimmune disease, HIV infection, depression, bipolar disorder
• Social history:
  • dietary intake:
    • typical daily food intake, snacking habits (obesity, primary hypertension)
      • ask about home cooked vs processed foods
    • salty foods (primary hypertension)
      • ask about table salt (free access to saltshaker), salty seasonings used in foods
  • recreational drugs: methamphetamine, cocaine, phencyclidine (PCP), anabolic steroids, ephedra (in some weight loss “supplements;” illegal in US)
  • smoking or vaping
  • activity level, exercise habits
  • stressors at home/school
  • tobacco smoke exposure in the home (primary hypertension)
• Family history: hypertension (primary or secondary), early myocardial infarction [MI], stroke, diabetes, OSA, hearing loss (Alport syndrome), kidney disease, need for dialysis/kidney transplant

Vitals:

• Take blood pressures on all four extremities (“4-point BPs”)
  • A significant drop in BP from upper to lower extremities (often cited as >20 mmHg) is suggestive of coarctation of the aorta
    • Typically the BP in the legs is about 20 mmHg higher than in the arms
• Assess for tachycardia (hyperthyroidism, pheochromocytoma [PCC], neuroblastoma)

Pertinent physical exam findings (and associated diseases)

• Head/face:
  • elfin facies (Williams syndrome)
    • broad forehead, flattened nasal bridge, wide-spaced eyes, long philtrum, small and widely spaced teeth, wide mouth, small chin
  • moon facies (Cushing syndrome)
    • rounded face (lower face/sides)
• Eyes:
  • proptosis (hyperthyroidism)
  • non-dilated ophthalmoscopic exam:
    • retinal changes: arteriovenous nicking, retinal hemorrhages, cotton wool patches (suggestive of severe [more often secondary] hypertension)
    • papilledema: obscured optic disc margins (intracranial hypertension)
• Throat:
  • tonsillar hypertrophy (obstructive sleep apnea)
• Neck:
  • thyromegaly/goiter (hyperthyroidism)
  • webbed neck (Turner syndrome)
• Chest wall:
  • widely spaced nipples (Turner syndrome)
• Cardiovascular (CV):
  • heart murmur (coarctation of the aorta)
  • friction rub (collagen vascular disease; pericarditis in systemic lupus)
  • apical heave (left ventricular hypertrophy [LVH] as seen in severe/chronic hypertension)
  • diminished or delayed lower extremity pulses (coarctation of the aorta)
• Abdomen:
  • abdominal mass/palpable kidneys (Wilms tumor, neuroblastoma, polycystic kidney disease, hydronephrosis, multicystic dysplastic kidney)
  • bruit over the epigastrium or flank (renal artery stenosis [RAS])
  • obesity (more common in primary hypertension)
  • truncal obesity (Cushing syndrome, corticosteroid therapy)
• Genitourinary:
  • ambiguous/virilized genitalia (congenital adrenal hyperplasia)
  • precocious puberty (intracranial tumors)
• Extremities/musculoskeletal:
  • joint swelling (collagen vascular disease, systemic lupus, vasculitis)
  • edema (chronic kidney disease, glomerulonephritis, heart failure)
  • muscle weakness (Liddle syndrome, hyperaldosteronism)
• Skin:
  • pallor (anemia of CKD, sickle cell anemia)
  • acne, hirsutism, striae (Cushing syndrome, corticosteroid therapy, anabolic steroid abuse)
  • café-au-lait spots, neurofibromas (neurofibromatosis [NF])
  • ash leaf spots, adenoma sebaceum (tuberous sclerosis [TS])
  • malar rash (systemic lupus)
  • palpable purpura (vasculitis)
  • acanthosis nigricans (type 2 diabetes mellitus)

Historical data to review

• Growth history: excessive weight gain/loss, change in growth percentiles (obesity, thyroid dysfunction)
• Blood pressure data from other healthcare encounters
  • Home BP data if available (ask if family has a home BP cuff or anyone at home who is trained to measure blood pressures)
• Prior episodes of UTI or unexplained fever suspicious for UTI/pyelonephritis
• Prior imaging data
  • Kidney/bladder ultrasound (cystic kidney disease, congenital anomalies, hydronephrosis, evidence of scarring from pyelonephritis or VUR, nephrocalcinosis, etc.)
  • VCUGs (to evaluate for VUR)
  • Echocardiography (to evaluate for left ventricular hypertrophy)

3. Confirm the patient has persistent hypertension

• If available, review historical data
  • Ensure historical BPs are contextualized: review them against the appropriate blood pressure percentiles for the patient’s age and height at the time the data was collected
• Educate on lifestyle modifications (e.g., healthy diet, sleep, physical activity), and schedule another office visit to recheck the blood pressure
  • Elevated BP: recheck BP in 6 months
    • If still in elevated range, check upper and lower extremity BPs (same visit), and repeat BP check in 6 months
      • If still elevated, perform 24-hour ABPM (if available), start diagnostic evaluation, and consider subspecialty referral
        • Continue to monitor at annual checkups: significant risk for progression to HTN in adolescence/adulthood
  • Stage 1 HTN: repeat in 1-2 weeks
    • If still in stage 1 range, check upper and lower extremity BPs (same visit), and repeat BP check in 3 months
      • If still in stage 1 range, perform 24-hour ABPM (if available), start diagnostic evaluation, initiate treatment, and consider subspecialty referral
  • Stage 2 HTN: check upper and lower extremity BPs (same visit), and repeat BP check in 1 week
    • If still in stage 2 range, perform 24-hour ABPM (if available), start diagnostic evaluation, initiate treatment, and refer for subspecialty evaluation

4. Proceed with a basic laboratory and imaging evaluation

Laboratory evaluation

• All children with persistent hypertension should have:
  • Basic metabolic panel (BMP, chem 7)
  • Urinalysis with microscopic exam
  • Lipid testing, nonfasting (non-HDL cholesterol or full lipid profile)
• In children with hypertension who are obese, also evaluate for comorbidities:
  • Hemoglobin A1c to screen for diabetes mellitus (DM)
  • Alanine aminotransferase (ALT) to screen for nonalcoholic fatty liver disease (NAFLD)
• If risk factors are present based on history, examination, initial labs, consider obtaining:
  • Thyroid stimulating hormone (TSH)
  • Urine drug screen
  • Sleep study (polysomnogram)
  • Complete blood count (CBC), especially in those with growth delay and/or abnormal kidney function
• Not routinely recommended for HTN evaluation, but may be considered if risk factors present: serum uric acid, urine microalbumin

Imaging evaluation

• Kidney bladder ultrasound (KBUS)
  • Useful for determining presence of congenital anomalies (including solitary kidney) or abnormalities in kidney parenchyma (e.g., thinning or discrepancies in kidney length) which may suggest scarring
  • At a minimum, guidelines recommend a screening ultrasound in any of the following:
    • All patients <6 years of age
    • Abnormal urinalysis (UA)
    • Abnormal kidney function
  • Practice will vary by institution, but an ultrasound may be obtained:
    • At the time of initial evaluation for patients referred for hypertension
    • After the diagnosis of hypertension is confirmed
    • Only in select patients, based on the above criteria and/or if other risk factors are present
  • Consider doppler ultrasound of the renal arteries
    • Sensitivity is variable but may be done to avoid more invasive testing
    • Best results in children ≥8 years of age who are of normal weight and able to cooperate with the exam when performed at a center with pediatric experience
      • If these criteria are not met, doppler ultrasound may have poor sensitivity; consider CTA/MRA
    • In the case of abnormally low resistive indices and/or tardus parvus waveforms, consider a narrowing of the suprarenal aorta [PMID 24037085]
• CT angiography (CTA), MR angiography (MRA)
  • Poorly studied in children, but one study including both adults and children showed a sensitivity and specificity ≥90% [PMID 17497443]
• Renal angiography (digital subtraction angiography)
  • Consider if there is a strong concern for renal artery stenosis/renovascular hypertension, even if doppler US/CTA/MRA were negative
    • Factors that raise suspicion for RAS/renovascular hypertension:
      • Stage 2 HTN, particularly if no other risk factors
        • Difficult to control HTN (despite ≥2 medications)
        • Significant diastolic HTN
        • Severe HTN after kidney transplant
        • Significant rise (>30%) in creatinine after ACE inhibitor initiation (if suprarenal/bilateral RAS)
      • Discrepant kidney sizes
      • Unexplained
        hypokalemia
      • Presence of bruit on exam
      • Disease associated with RAS (vasculitis or genetic syndrome)
• Echocardiography
  • Should be performed to evaluate for left ventricular hypertrophy (LVH), geometry (concentric vs eccentric), and function (ejection fraction)
  • Defining left ventricular hypertrophy (LVH):
    • ≥8 years: LV mass index (LVMI) >51 g/m^2.7 (boys and girls)
    • <8 years: divide LV mass by body surface area (BSA)
      • Boys: LV mass >115 g/m2
      • Girls: LV mass >95 g/m2
      • See: kidney.wiki BSA calculator
  • If abnormalities present, repeat every 6 months to monitor for improvement/progression
  • If no abnormalities present, consider repeating every 12 months if: HTN persists despite treatment