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Hindawi Publishing CorporationInternational Journal of PediatricsVolume 2012, Article ID 537936, 8 pagesdoi:10.1155/2012/537936
Review Article
Prematurity-Related Hypertension in Children and Adolescents
Karolina Poplawska,1 Karolina Dudek,2 Maja Koziarz,2 Dominik Cieniawski,2
Tomasz Drożdż,2 Sylwester Śmiałek,2 Dorota Drożdż,3 and Przemko Kwinta1
1 Department of Pediatrics, Polish-American Children’s Hospital, Jagiellonian University Medical College, Wielicka 265 Street,30-663 Cracow, Poland
2 Medical Student’s Research Assosciation, Jagiellonian University Medical College, Wielicka 265 Street, 30-663 Cracow, Poland3 Department of Pediatric Nephrology, Polish-American Children’s Hospital, Jagiellonian University Medical College,Wielicka 265 Street, 30-663 Cracow, Poland
Correspondence should be addressed to Przemko Kwinta, [email protected]
Received 14 October 2011; Accepted 29 November 2011
Academic Editor: Umut Selda Bayrakci
Copyright © 2012 Karolina Poplawska et al. This is an open access article distributed under the Creative Commons AttributionLicense, which permits unrestricted use, distribution, and reproduction in any medium, provided the original work is properlycited.
Due to the functional and structural immaturity of different organ systems, preterms have a higher rate of morbidity and mortality.The prevention and treatment of the complications of prematurity is a major challenge in perinatal health care. Recently, therehave been several multicenter research trials analysing the impact of prematurity or low birth weight on the health problems ofchildren and adolescents. Many of these studies deal with the issue of pediatric hypertension. An analysis of 15 studies conductedin the years 1998–2011, in which blood pressure values in ex-preterm children were measured, was performed. Comparison wasbased on several issues: measurement method, cohorts age, size, and birthweight. It has been proven that hypertension occurs moreoften in former preterm infants; however the etiologic pathways that cause this condition still remain unclear. Moreover, pediatrichypertension is a significant problem, because of its transformation into adult hypertension and increased cardiovascular risklater in life. Therefore it is crucial to introduce wide-spread screening and detection of elevated blood pressure, especially amongprematurely born children.
1. Prematurity
Prematurity is defined as the birth of a child before 37weeks of gestational age [1]. Infants born before 32 weeksare defined as “very preterm” and born before 28 weeksas “extremely preterm” newborns. It is estimated that thepercentage of prematurely born children in most developedcountries is about 5–7%. The prevalence in the United Statesis even higher, almost 13% [2].
There are many causes of preterm birth, such as spon-taneous preterm labour, premature rupture of membranes,multiple gestations and assisted reproduction, eclampsia,intrauterine growth restriction, antepartum haemorrhage,cervical insufficiency, and uterine malformations. Accordingto recent research studies, severe prematurity is mainlycaused by infection or inflammation and abnormal vascular
or placental development [3]. More than 50% of deliveriesprior to 32 weeks have an inflammatory association [4].
Preterm birth is a major challenge in perinatal healthcare, mainly due to the various complications affecting thesenewborns. Advances in perinatal medicine have led to a con-tinuous decrease in mortality of extremely low birth weight(ELBW) and extremely preterm infants [5]. Early compli-cations (more severe in ELBW newborns) are respiratorydistress syndrome, intraventricular hemorrhage, patent duc-tus arteriosus, and necrotizing enterocolitis and sepsis. Themost dynamic complications occur in the first few weeks,but prematurity also influences health issues later in life. Latecomplications mainly include bronchopulmonary dysplasiaretinopathy of prematurity [6–8]. Recently, there have beenseveral multicenter research trials analysing the impact ofprematurity or low birth weight on the health problems of
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2 International Journal of Pediatrics
children and adolescents. Many of these studies deal with theissue of hypertension (HT).
2. Hypertension in Ex-Preterm Newborns
A general description of studies from last 13 years in whichblood pressure (BP) values in ex-preterm children weremeasured is presented in Table 1. In 8 out of 15 of theanalyzed studies in addition to the measurement of BPvalues, the diagnosis of hypertension was also made [9–16].
Based on the age of the included subjects, studies canbe divided into groups: evaluating school-aged children(6–12 years) [10–12, 16, 23], adolescents (13–18 years)[15, 17, 22], and adults (18–30 years) [9, 13, 14, 18–21]. Theprevalence of hypertension in all studies ranged from 6 to25%. In subjects from 6 to 12 years old the prevalence ofhypertension was 10–25% [10–12, 16], in the adolescentgroup 16% [15], and in the adult group 6–10% [9, 13, 14].According to this data it may seem like the prevalence ofHT decreases with age. However it should be noted thatthese studies span the last 30 years during which advances inneonatal intensive care have increased the survival rates ofex-preterm infants exponentially. Before the 1970s only 10%of extremely low birth weight (ELBW) infants (500–999 g)or very preterm infants (
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International Journal of Pediatrics 3T
abl
e1:
Sele
cted
clin
ical
tria
lsco
mpa
rin
gB
Pva
lues
indi
ffer
ent
grou
psof
child
ren
.
Stu
dyPa
tien
ts’a
geSt
udy
popu
lati
onC
ontr
olgr
oup
Mai
nco
ncl
usi
ons
Ph
aroa
het
al.[
17],
Un
ited
Kin
gdom
,199
815
year
s12
8V
LBW
128
NB
WT
he
syst
olic
bloo
dpr
essu
rew
assi
gnifi
can
tly
hig
her
inca
ses
than
inco
ntr
ols.
Th
edi
asto
licpr
essu
rew
asal
soh
igh
erbu
tth
edi
ffer
ence
was
not
sign
ifica
nt.
Kis
tner
etal
.[18
],Sw
eden
,200
026
year
s33
(15
gest
atio
nal
wee
k<
32;1
8bi
rth
wei
ght≤2
600
g)17
NB
WP
rete
rms
had
sign
ifica
ntl
yh
igh
erca
sual
syst
olic
and
mea
nar
teri
albl
ood
pres
sure
leve
lsco
mpa
red
toco
ntr
ols.
Doy
leet
al.[
19],
Au
stra
lia,2
003
18ye
ars
156
VLB
W38
NB
WB
Pw
assi
gnifi
can
tly
hig
her
inla
tead
oles
cen
cein
VLB
Wsu
rviv
ors
than
inN
BW
subj
ects
.Gro
wth
rest
rict
ion
inu
tero
was
not
sign
ifica
ntl
yre
late
dto
BP
inV
LB
Wsu
rviv
ors.
Hac
ket
al.[
20],
Un
ited
Stat
es,2
005
20ye
ars
195
VLB
W20
8N
BW
VLB
Win
divi
dual
sh
ada
hig
her
mea
nsy
stol
icbl
ood
pres
sure
(SB
P)
than
nor
mal
birt
hw
eigh
t(N
BW
)co
ntr
olin
divi
dual
s(1
14+
/−11
vers
us
112
+/−
13m
mH
g;P=
0.04
7).D
BP
did
not
diff
erbe
twee
ngr
oups
.Th
era
tes
ofhy
per
ten
sion
did
not
diff
ersi
gnifi
can
tly
betw
een
the
grou
ps.
Kei
jzer
-Vee
net
al.[
9],
Net
her
lan
ds,2
005
19ye
ars
588
(418
gest
atio
nal
wee
k<
32;
170
gest
atio
nal
wee
k≥3
2an
dbi
rth
wei
ght<
1500
g)—
Th
epr
eval
ence
ofhy
per
ten
sion
ish
igh
erin
indi
vidu
als
wh
ow
ere
born
pret
erm
wh
enco
mpa
red
wit
hth
ege
ner
alpo
pula
tion
.Bir
thw
eigh
tSD
San
dge
stat
ion
alag
ebo
thdi
dn
otaff
ect
the
risk
for
hyp
erte
nsi
on.
Rod
rigu
ez-S
oria
no
etal
.[1
0],S
pain
,200
56–
12ye
ars
40E
LBW
43N
BW
Syst
olic
,dia
stol
ic,a
nd
mea
nbl
ood
pres
sure
sdi
dn
otdi
ffer
betw
een
case
san
dco
ntr
ols.
Shan
kara
net
al.[
11],
Un
ited
Stat
es,2
006
6ye
ars
144
wit
hIU
GR
372
full-
term
Inte
rmin
fan
tsIU
GR
was
linke
dto
risk
ofhy
pert
ensi
onin
earl
ych
ildh
ood.
Rel
ativ
eri
skco
mpa
red
toco
ntr
olgr
oup
was
1,8.
Bay
rakc
iet
al.[
12],
Turk
ey,2
007
5–17
year
s41
pret
erm
s(<
37w
eeks
ofge
stat
ion
)27
full-
term
Th
ere
isan
inve
rse
corr
elat
ion
betw
een
hig
hn
igh
ttim
eSB
PSD
San
dbi
rth
wei
ght.
Ligh
tnes
sfo
rda
tew
asdi
scov
ered
asa
maj
orpr
edic
tor
ofbo
thn
octu
rnal
and
dayt
ime
SBP
SDS.
Noc
turn
alSB
PSD
Sw
ascl
osel
yco
rrel
ated
wit
h24
hH
RSD
S.24
hH
RSD
Sw
asel
evat
edin
non
dipp
ers.
Pre
term
sh
ave
incr
ease
dn
octu
rnal
SBP
resu
ltin
gin
grea
ter
freq
uen
cyof
non
dipp
ers.
Pyh
älä
etal
.[21
],Fi
nla
nd,
2009
23ye
ars
44V
LBW
37N
BW
Inco
mpa
riso
nw
ith
the
con
trol
grou
pth
eV
LBW
grou
ph
adh
igh
ersy
stol
ican
ddi
asto
licbl
ood
pres
sure
but
the
grou
pdi
ffer
ence
sw
ere
not
stat
isti
cally
sign
ifica
nt.
Lurb
eet
.al[
22],
spai
n,
2009
10–1
8ye
ars
114
LBW
308
NB
WO
bese
low
birt
hw
eigh
tsu
bjec
tsh
adth
eh
igh
est
syst
olic
BP
valu
esov
erth
e24
hou
rs,w
her
eas
the
non
obes
esu
bjec
tsin
the
abse
nce
oflo
wB
Wh
adth
elo
wes
tva
lues
.No
inte
ract
ion
exis
ted
betw
een
obes
ity
and
low
birt
hw
eigh
tin
the
office
oram
bula
tory
syst
olic
bloo
dpr
essu
re.
Kei
jzer
-Vee
net
al.[
13],
Net
her
lan
ds,2
010
20ye
ars
50ve
rypr
emat
ure
indi
vidu
als
<32
wee
ksof
gest
atio
n(2
1SG
A,
29A
GA
)
30fu
ll-te
rm
SGA
had
low
erw
eigh
tan
dh
eigh
tth
anA
GA
.th
ere
wer
eN
odi
ffer
ence
sin
BM
Iw
ere
fou
nd.
InSG
Am
ore
mot
her
sh
adhy
per
ten
sion
duri
ng
preg
nan
cy.M
enh
adsi
gnifi
can
tly
hig
her
SBP
and
low
erH
R.A
GA
–hig
her
dayt
ime
SBP,
base
line
SBP,
SBP
load
.SG
Ave
rsu
sA
GA
.Th
ere
wer
en
odi
ffer
ence
sin
SBP,
DB
P,H
F,an
dM
AP
load
s.N
ewbo
rns
born
very
prem
atu
rely
hav
eh
igh
erSB
Ps,
but
IUG
Rh
asn
oeff
ect
onit
.H
ovie
tal
.[14
],Fi
nla
nd,
2010
18–2
7ye
ars
118
VLB
W12
0N
BW
Hig
her
rate
sof
hype
rten
sion
and
hig
her
24-h
our
bloo
dpr
essu
rein
VLB
Wgr
oup
wer
eob
serv
ed.
Voh
ret
al.[
15],
Un
ited
Stat
es,2
010
16ye
ars
296
(bir
thw
eigh
t<
1250
g)95
NB
W
Th
epr
imar
ypr
edic
tors
ofin
crea
sed
syst
olic
bloo
dpr
essu
rew
ere
wei
ght
gain
velo
city
betw
een
birt
han
d36
mon
ths,
pre-
ecla
mps
ia,n
onw
hit
era
ce,a
nd
mal
ege
nde
r.P
redi
ctor
sof
dias
tolic
bloo
dpr
essu
rew
ere
wei
ght
gain
velo
city
betw
een
birt
han
d36
mon
ths,
brai
nin
jury
,an
dm
ale
gen
der.
Fatt
al-V
alev
skie
tal
.[2
3],I
srae
l,20
118–
12ye
ars
64IU
GR
(mea
nbi
rth
wei
ght
1780±
422
g;42
%pr
eter
ms)
64N
BW
Syst
olic
bloo
dpr
essu
reva
lues
wer
esi
gnifi
can
tly
low
erin
the
IUG
Rgr
oup
com
pare
dto
the
con
trol
s.T
her
ew
asn
odi
ffer
ence
indi
asto
licbl
ood
pres
sure
valu
es.I
nth
eIU
GR
grou
p,sy
stol
icbl
ood
pres
sure
corr
elat
edsi
gnifi
can
tly
wit
hcu
rren
tw
eigh
tan
dbo
dym
ass
inde
x,an
ddi
asto
licbl
ood
pres
sure
wit
hw
eigh
tga
inbe
twee
nag
e2
and
4ye
ars.
Non
eof
the
bloo
dpr
essu
reva
lues
corr
elat
edw
ith
birt
hw
eigh
t.
Kw
inta
etal
.[16
],Po
lan
d20
116–
7ye
ars
78E
LBW
38N
BW
Hyp
erte
nsi
onw
asdi
agn
osed
in10
.3%
ofpa
tien
tw
ith
ELB
W.I
nco
ntr
olgr
oup
hype
rten
sion
was
pres
ent
in5.
2%ca
ses
but
the
diff
eren
cew
asn
otsi
gnifi
can
t.St
atis
tica
llysi
gnifi
can
tdi
ffer
ence
sw
ith
inn
igh
t-ti
me
mea
nbl
ood
pres
sure
,nig
ht-
tim
ebl
ood
pres
sure
dipp
ing,
and
mea
nsy
stol
ican
ddi
asto
licB
Plo
adw
ere
dete
cted
-
4 International Journal of Pediatrics
In another study only nighttime SBP was elevated [12]. Bothdaytime and nighttime SBPs were significantly elevated in 2studies [19, 22]. For DBP there was no such correlation inany of the aforementioned studies.
Analysis of studies performed before 2008 revealed hy-pertension in 10–25% of ex-preterms, compared to 6–16% instudies from the last 3 years. Furthermore, in recent studiesABPM was used more frequently. There was no differencebetween patients’ age and birth weight on follow-up. Basedon the fact that through the years the diagnostic methodsand criteria for HT in pediatric patients are more precise,children are less frequently overdiagnosed. This can explainthe differences in HT prevalence between recent and olderstudies.
Six of the analyzed studies included patients from onlyone medical care unit. However, two of the one-center stud-ies comprised of a large amount of study subjects (114 and156 patients) [19, 22]. The prevalence of hypertension inthese studies extended from 10 to 25% in former pretermchildren. More valuable studies are conducted nationwidedue to their diversity and the limited influence of randomvariables on test results [9, 13]. In these studies the preva-lence of hypertension was 6–10.3%. Studies involving largeadministrative areas of the country revealed a hypertensionprevalence comparable to those nationwide and multicenter[14, 16, 17]. It is worth mentioning that in American mul-ticenter studies the prevalence of hypertension was definitelyhigher (16–24%) than that in the corresponding Europeanstudies [11, 15]. The reason for this phenomenon might bethe occurrence of more (besides prematurity) risk factors forHT development in American children such as black race andobesity.
To summarize, all the aforementioned studies were fo-cused on different aspects of HT risk in ex-preterm children.The results are diversified and controversial in many cases.These discrepancies indicate the necessity of more multi-center and nationwide studies on larger populations. Con-ducting follow-ups in the same groups in intervals every fewyears during whole life might enable understanding of theproblem of HT in prematurely born children.
3. Pathophysiology of Hypertension inEx-Preterm Children
Impaired renal development in premature newborns hasbeen proven to be related to hypertension later in life, how-ever the etiologic pathways that cause this phenomenon stillremain unclear. Impaired intrauterine kidney growth maylead to a reduction in the number of nephrons, which is char-acteristic for hypertensive patients’ kidneys [26]. Recentstudies have shown that in preterm infants glomerulogenesisas measured by radial glomerular counts was markedly de-creased in comparison to term controls. Although theduration of glomerulogenesis is 40 days, the structureof preterm infants kidneys differs from that of the full-term infant [27]. Moreover, postnatal kidney growth ofpremature infants is impaired up until the second yearof life [28, 29]. It is also worth mentioning that the use
of nonsteroidal anti-inflammatory drugs during pregnancyand the newborn period can impair both renal struc-ture and function [30]. A significant difference in renalvolume has been proved to be present in ex-pretermsat the age of 7, namely, relative right (86% ± 17 ver-sus 99% ± 16 P < 0.001) and left (85% ± 19 versus95% ± 18 P = 0.01) kidney volume in ex-preterms andcontrols, respectively [16].
Other theories assume that pathogenetic mechanismssuch as increased tubular sodium channel expression, dysreg-ulation of the intrarenal renin-angiotensin system, continu-ous oxidative stress, and decreased nitric oxide productionleading to impaired endothelium-derived vasodilatation mayplay a role in inducing elevated BP in prematurely borninfants [12, 31, 32].
Many studies emphasize the effect of metabolic imprint-ing on ex-preterm children and adolescents. The term “met-abolic imprinting” refers to the basic biological phenomenathat states that there is an underlying relationship betweennutritional experiences early in life and chronic diseases laterin life [33]. According to this theory, nutrition in early lifehas a major impact on health into early adulthood, notablyon cardiovascular disease risk, bone health, and cognitivefunction. It has been shown in several studies that impairednutrition in the perinatal period was linked to dysfunctionof endothelium-dependent vasodilatation at birth and laterin childhood [34, 35]. Several observations revealed that in-fants who were fed growth-promoting enriched diets had agreater risk of developing the main components of metabolicsyndrome in the future. Greater nutrient intake in infancyis associated with raised BP and insulin resistance in adults[36, 37]. Multiple retrospective studies in diverse populationshave shown that birth weight is inversely correlated withadult BP; thus the existence of a biological link betweenintrauterine growth and adult blood pressure is stronglysuspected. Furthermore, several studies emphasize the effectof prenatal undernutrition on BP elevation. They have dem-onstrated that increased SBP was related to decreasedmaternal protein intake [33].
Another important point is the role of the sympatheticnervous system in the programming of hypertension [12].In animal models, an increase in serum epinephrine levelsinversely correlated to birth weight, which suggested anincrease of adrenal medullary function [38]. It has also beenshown that in SGA infants there is an increase in activityof the sympathetic component of the heart rate response.According to this data, it can be observed that the influenceof the autonomous nervous system is programmed earlyin life. Being born SGA is associated with a greater risk ofhigh blood pressure and other cardiovascular diseases inadulthood, especially where postnatal catch-up growth isapparent [39]. An American study analyzing the occurrenceof prehypertension and hypertension in a group of formerpreterm infants at 16 years of age showed that an increasedacceleration of weight gain between birth and 36 monthswas related to higher systolic and diastolic BP [15]. Sinceearly weight gain catch-up has also been associated withobesity and insulin resistance in various studies [40, 41], it
-
International Journal of Pediatrics 5
can increase the risk for cardiovascular disease later in life.
4. Target-Organ Damage
Recent data has shown that children and adolescents with amild elevation in blood pressure are much more commonthan it was thought in the past [42]. Pediatric hypertensionis a significant problem, because it frequently carries on intoadult hypertension and increases the cardiovascular riskin later life [43–45]. Target organ abnormalities are com-monly associated with hypertension in children and laterin adults. This damage can be detected already even inyoung patients. In addition since there are no publicationsdescribing hypertension-related repercussions in pretermborn children, we could suppose that they are exposed tosimilar complications of elevated BP as other children, fornow, there are no documented discrepancies between therepercussions of hypertension in full- and preterm bornchildren. In essential hypertension assessment of early organdamage provides a useful tool for treatment decisions [46].
The most frequently targeted organs damaged in child-hood due to hypertension are the heart and blood vesselssuch as the coronary vessels, the cerebral vessels, and thevessels, in the kidney. Left ventricular hypertrophy (LVH) isthe most remarkable sign of targeted organ damage causedby hypertension in children and adolescents [42]. The prev-alence of LVH in children with hypertension varies from 14to 42% [47–49]. The best tool to assess LVH is echocar-diography, which should be performed after the diagnosisof HT has been made and periodically thereafter. The pres-ence of LVH is one of the indications to initiate or inten-sify antihypertensive therapy [50]. Intima-media thickening(IMT) is another consequence of the effect of childhoodhypertension on blood vessels. It is used to detect patientsat a high risk for developing atherosclerosis in later life. Ad-ditionally arterial stiffness which is connected to IMT hasbeen reported to be more frequent in hypertensive children[51]. Hypertension-related kidney damage is manifested byreduced renal function or Urinary Albumin Excretion(UAE). Microalbuminuria could be an early marker ofkidney injury and also a predictor of LVH in children withessential hypertension [42, 52]. Impairment of cognitivefunction could be a result of narrowing of the small vesselsin brain. It may also cause hypoperfusion and demyelination[53]. Retinal arteriolar narrowing is also a commonly knownconsequence of HT in children [46].
We could speculate that these changes occur earlier inex-preterm children and adolescents, however there are nopublications available on this subject at this time. It is essen-tial to perform multicenter studies addressing the compli-cations of hypertension in ex-preterm children.
5. Hypertension Risk Factors in Ex-Preterms
In unselected population of very young children (less than6 years), hypertension is caused in most cases by renal pa-renchymal diseases such as glomerulonephritis, renal scar-ring, polycystic kidney disease, renal artery stenosis, and
renal dysplasia [42]. These conditions and coarctation ofthe aorta together account for 70–90% of all cases ofhypertension [46]. Over the age of 6 years more cases ofessential hypertension start to occur.
It is a well-known fact that similar to adults, in childrenand adolescents, one of the most important risk factors ofhigh BP is Body Mass Index (BMI), family history, andfactors that the metabolic syndrome is composed of such aslow plasma high-density lipoprotein, elevated plasma triglyc-erides, abdominal obesity, and insulin resistance [54–56].Compared to their term sex- and age-matched lean coun-terparts, ex-preterms are affected by secondary hypertensionmuch more frequently than essential. However, in numerousstudies, significantly lower BMI values in ex-preterms havebeen confirmed, indicating that this group is thinner thancontrols, therefore diminishing the role of BMI, as a riskfactor in this group of patients [21, 22]. Therefore in thisgroup of patients, family history, BMI, and dyslipidemia areless important risk factors than those in the general pediatricpopulation. It has been proven that obesity and being an ex-preterm infant are independent risk factors of hypertension[22].
6. Diagnostic Difficulties
Childhood hypertension is often asymptomatic or presentswith uncharacteristic symptoms, such as headache, epistaxis,shortness of breath, and changes in behavior or schoolperformance. Therefore it can be easily underdiagnosed.Diagnostic problems occur more often in children than theydo in adults. These issues are common in all pediatric pa-tients, regardless of their birth weight or prematurity. Theyare also habitually present in ex-preterms.
The first group of problems are technical issues related toproper BP measurement such as the appropriate BP cuff sizeand difficulty with auscultation in small children [53]. Theseproblems occur more often in ex-preterms because they areoften smaller than ex-terms and have a thinner arm. It ismore difficult to match an appropriate BP cuff size to thisgroup of patients. Secondly, in pediatric patients a necessarycondition for proper BP measurement is the cooperation ofthe child. It has been proven that preterm infants are at ahigh risk of developing cerebral palsy. On the other hand,some ex-preterm infants are hyperactive which also make BPmeasurement difficult [57, 58]. Moreover, BP measurementscan be overestimated more often in ex-preterms because ofthe children nervousness and hyperactivity.
The second group of problems, that both occur in ex-preterms and in ex-term infants alike, are two phenomenaconnected with hypertension: White Coat Hypertension(WCH) and masked hypertension. Only using office mea-surements of BP may be insufficient and could cause mis-diagnosis and inappropriate treatment; thus a very usefulmethod in the diagnosis of these phenomena is AmbulatoryBlood Pressure Monitoring (ABPM) [59]. Ambulatory BPvalues are better markers of cardiovascular and renal riskthan its office BP counterparts [60]. ABPM is also useful forevaluating patients with episodic hypertension, chronic kid-ney disease, diabetes, and autonomic dysfunction [50, 61].
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6 International Journal of Pediatrics
Despite having many benefits, this method also has its limi-tations that are especially apparent in ex-pretem population.One of them is lack of reference values of AMBP in childrenwith a height below 120 cm. An essential matter in childrenborn with low birth weight (LBW) is that they are shorter andweigh less than children from the general population. Thus, agreat number of these patients do not match ABPM criteria,which leads to the underdiagnosis of hypertension.
Therefore, further studies concerning children shorterthan 120 cm should be conducted in order to generate AMBPstandards in this group of patients. Though hard to execute,similar research studies in ex-preterm and IUGR infantswould provide more accurate and earlier hypertension dia-gnosis.
7. Future Priorities
Regarding the increasing number of pediatric patients withhypertension and the severity of its complications, it iscrucial to introduce wide-spread screening and detection ofelevated blood pressure, especially among prematurely bornchildren. Recent studies, comprising of prematurely born orLBW infants, clearly indicate a higher risk of hypertensionin this group of patients [12, 13]. In consequence, futurestudies should focus on early and appropriate evaluationof the presence of high blood pressure values in formerpreterms. Furthermore, long-term, follow-up observationsof BP should be performed in cohorts of ex-preterms aged 5,10, 15, and 20 years old to determine BP elevation progres-sion and its dynamics, the odds of developing hypertension,and the number of newly diagnosed hypertension casesin time. It could be a valuable extension of Lurbe et al.study concerning LBW newborns in which BP was measuredduring first year of life at 1, 3, 9, and 12 months of age [62].It revealed that LBW infants had lower SBP and DBP at birththan normal weight children, but this relation was reversedafter the 1st month. Because premature infants are at agreater risk for hypertension than full-term newborns, earlyrestriction of its consequences is vital, and therefore furtherstudies concerning this matter ought to be conducted.Due to lack of corresponding research studies in preterminfants, surveys regarding sodium intake reduction and ACEinhibitors implementation as possible alleviating factors ofhypertension must be conducted [63, 64].
Abbreviations
ABPM: Ambulatory blood pressuremonitoring
AGA: Appropriate for gestational ageBMI: Body mass indexBP: Blood pressureDBP: Diastolic blood pressureELBW: Extremely low birth weightHT: HypertensionIMT: Intima-media thickeningIUGR: Intrauterine growth restrictionLBW: Low birth weightLVH: Left ventricular hypertrophyNBW: Normal birth weight
MAP: Mean arterial pressureSBP: Systolic blood pressureSGA: Small for gestational ageUAE: Urinary albumin excretionWCH: White coat hypertensionVLBW: Very low birth weight.
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