2074 Original article
Simple renal cysts and arterial hypertension: does their
evacuation decrease the blood pressure?
Enver Zerema, Goran Imamovića and Safet Omerovićb
Objective To evaluate the relationships between simple
renal cysts and arterial hypertension and whether their
evacuation decreases the blood pressure (BP).
hypertensive patients (P < 0.001). There were less
hypertensive patients 3 days after treatment than before
treatment (P < 0.0001).
Methods In a cross-sectional design, we analyzed
184 study participants with cysts and compared
hypertensive and nonhypertensive among them. Outcomes
were the number, the size and the location of a cyst. In a
cross-over design, we first evaluated the change in absolute
value of SBP, DBP and mean BP in 62 hypertensive patients
who underwent percutaneous evacuation of a cyst and then
the decrease of BP as a categorical variable that comprised
all study participants.
Conclusion An apparent association between the size of
a simple renal cyst and hypertension was found, and
aspiration of cysts resulted in a reduction of BP. Location
and number of cysts were not related to BP. J Hypertens
27:2074–2078 Q 2009 Wolters Kluwer Health | Lippincott
Williams & Wilkins.
Journal of Hypertension 2009, 27:2074–2078
Keywords: blood pressure, location of cysts, size of cysts
Results There were 55% giant renal cysts among
hypertensive and 24% among nonhypertensive patients
(P U 0.0001). The prevalence rates of multiple and
peripheral cysts in hypertensive and nonhypertensive
patients were similar to those of single and perihilar cysts,
respectively. Significant differences in SBP, DBP and mean
BP were found between pretreatment readings and 3 days,
1 month, 3 months and 6 months after cyst evacuation
(P < 0001). The differences were significant in all
Received 18 February 2009 Revised 15 May 2009
Accepted 5 June 2009
Introduction
Methods
Most benign renal cysts are asymptomatic and require no
treatment. They can cause a variety of clinical symptoms
when they are sufficiently large. The prevalence of
simple renal cyst, their number and size increase with
aging [1–4].
Design
The frequency of hypertension also increases with age,
thereby raising the issue of possible association between
cysts and hypertension [2,5,6]. The evidence that simple
renal cysts are an important cause of hypertension
remains unconvincing. Several authors reported that
simple renal cyst was related to high blood pressure
(BP) in cross-sectional studies [6,7], and the reduction
of BP after aspiration or removal of large cysts was also
observed [8,9]. The other reports showed the disputable
[3,10] or opposite results [11,12].
According to currently available data, the relationship
between simple renal cyst and hypertension has not been
fully evaluated, yet. We conducted this study to evaluate
the relationship between simple renal cyst and hypertension and to evaluate whether their evacuation decreases
the BP.
0263-6352 ß 2009 Wolters Kluwer Health | Lippincott Williams & Wilkins
Abbreviations: BP, blood pressure; HT, hypertensive patients; IQR,
interquartile range; MBP, mean blood pressure; NT, normotensive patients
a
University Clinical Center, Tuzla and bGeneral Hospital Mostar, Mostar, Bosnia
and Herzegovina
Correspondence to Enver Zerem, MD, PhD, The University Clinical Center Tuzla,
Trnovac bb, Tuzla, Bosnia and Herzegovina
Tel: +38 761898202; fax: +38 735266485; e-mail: [email protected]
Cross-sectional and prospective cohort studies.
Setting
University teaching hospital in the town of Tuzla, Bosnia
and Herzegovina.
Participants
Inclusion criteria
All patients with a symptomatic simple renal cyst who were
admitted to our hospital between September 2000 and
August 2008 were considered as candidates for the study.
Patients were enrolled if they had a simple renal cyst confirmed by ultrasound or computed tomography (CT) scan.
Exclusion criteria
Exclusion criteria were infectious renal cysts, autosomal
dominant polycystic kidney disease (ADPKD) and cystic
tumor of the kidney.
Cross-sectional design
Sixty-two individuals with simple renal cyst and BP over
140/90 mmHg were included in the patients’ group. The
DOI:10.1097/HJH.0b013e32832f1458
Copyright © Lippincott Williams & Wilkins. Unauthorized reproduction of this article is prohibited.
Simple renal cysts and arterial hypertension Zerem et al.
patients’ group was compared with the control group
of 122 patients with symptomatic simple renal cyst
but without hypertension and who were also admitted
to our hospital during the same period. Outcome
measures were the number, the size and the location
of the cysts.
Cross-over designs
All patients underwent percutaneous evacuation and
sclerosation of a cyst. The evaluation of the BP was made
3 days after the procedure, thereby ruling out the adverse
impact of the procedure itself on the clinical status of a
patient. On the follow-ups after the first, third and sixth
months, BP measurements, laboratory tests and ultrasound examinations were performed. The evaluation
of the decrease of BP as a continuous variable resulting
from the repeated measurements was first made in
the patients’ group, followed by the evaluation of the
decrease of BP as a categorical variable that comprised all
184 study participants. Informed consent was obtained
from the participants, and the study was approved by the
local ethics committee.
Measurements
A detailed medical history was taken from each patient,
and physical examination was performed, including BP
measurement and standard ECG. The following patient
information was obtained: height, weight, age, sex, history of diabetes mellitus, history of hypertension, antihypertensive medication, BP, serum creatinine, blood
urea nitrogen, serum cholesterol, serum triglyceride,
serum low-density lipoprotein cholesterol, serum highdensity lipoprotein cholesterol and the urinalysis by a
dipstick and microscopy. All laboratory tests were performed after overnight fasting. We calculated BMI by
dividing the weight (kg) by square of the height (m2).
BP was measured three times during the first physical
examination and another three times just before percutaneous treatment of the cysts. On the control examination,
BP was measured the same way. Each measurement was
made on the right upper arm with a mercury sphygmomanometer in the supine position and expressed in millimeters of mercury (mmHg). Of the three measurements,
the mean value of the last two was recorded on the basis
of the first and fifth phase of the Korotkoff sounds for SBP
and DBP, respectively. The arithmetic mean was then
calculated using all available systolic and diastolic readings. The mean BP (MBP) was calculated using the
formula: MBP ¼ DBP þ (SBP DBP)/3. The same investigator performed all measurements, always between
0800 and 1000 h. In individuals who were on antihypertensive treatment, BP was measured before taking the
prescribed medication. Individuals were classified as
hypertensive patients if they had SBP of 140 mmHg or
higher or DBP of 90 mmHg or higher. Over the entire
2075
study period, we did not change the medication prescribed
to patients before percutaneous treatment.
Abdominal ultrasonongraphy was performed with ultrasound scanner Logiq 400 CL (General Electric, Milwaukee, Wisconsin, USA) and a 3.5 MHz probe. A simple
renal cyst was defined as an anechoic, unilocular fluidfilled space with imperceptible walls showing posterior
enhancement, and a sharp interface to the adjacent renal
parenchyma that did not have wall thickening, and
calcification on ultrasonography and a well demarcated
water-attenuation lesion with no contrast enhancement
on CT.
Evaluation of the size, the location, the number and echo
pattern of the cysts before treatment and during follow-up
examinations was based on ultrasound examinations. The
cysts’ volumes were calculated using ellipsoid formula,
multiplying the product of the three orthogonal diameters
by 0.523 (volume ¼ height width length 0.523). The
giant cyst is defined as a cyst larger than 500 ml in volume.
Multiple cysts are defined as more than two in number of
cysts. The cyst was considered to have disappeared if it
could no longer be visualized on ultrasound or the area was
replaced by an ill-defined echogenic area or normal echo
pattern. Percutaneous treatment of the cysts was performed by prolonged catheter drainage or by alcohol
sclerotherapy as the methods described in the previous
studies [2–4,13].
Statistical analysis
Statistical analyses were performed using MedCalc for
Windows, version 10.0.2.2. (MedCalc Software, Mariakerke, Belgium). To test the differences in quantitative
variables between the independent groups with normal
and not normal distribution, independent samples t-test
and Mann–Whitney test were done, respectively. Group
differences for categorical variable between three age
strata were assessed by chi-squared test for trend.
Repeated measurements analysis of variance (ANOVA)
was done to test the within-individual factors in quantitative variables after a log transformation to correct for a
lack of normality, where appropriate. To test the differences in qualitative variables, chi-squared and McNemar
tests were done for independent groups and paired observations, respectively. Two-sided P values were reported,
with 0.05 taken as the level of statistical significance.
Results
Arterial hypertension was found in 62 patients (33.7%)
among 184 patients (71 women and 113 men), who underwent percutaneous treatment of simple renal cysts. The
median age [interquartile range (IQR)] of all patients
was 56 (47–67) years, and the median BMI (IQR) was
25.7 (24.2–26.8) kg/m2. Hypertension was diagnosed in
29 women and 33 men, with a mean age of 58.6 10.7
(range 38–74) years and BMI 25.7 1.7 (range 23.3–29.7)
Copyright © Lippincott Williams & Wilkins. Unauthorized reproduction of this article is prohibited.
2076 Journal of Hypertension
Table 1
2009, Vol 27 No 10
Demographic and clinical characteristics of patients with renal cysts by blood pressure status
Characteristics
Patients with hypertension, n ¼ 62
Patients without hypertension, n ¼ 122
P
58.6 10.7
34/28 (55)
25.7 1.7
a
111.6 37.8
a
403.3 239.7
34/28 (55)
23/39
53/9
5.1 1.2
1.61 0.61
3.35 (2.6–4.2)
1.3 (1.1–1.4)
74.8 13.4
a
3.4 1.1
2/60
6/56
56.3 11.0
79/43 (65)
25.7 1.6
b
87 (72–109)
b
257 (126–456)
29/93 (24)
51/71
104/18
5.1 1.1
1.62 0.57
3.2 (2.6–4.2)
1.25 (1.1–1.4)
74.8 13.3
b
3.5 (2.6–4.7)
4/118
10/112
0.17
0.25
0.94
0.007M
0.01M
0.0001M
0.65
0.86
0.65
1.00
0.74
0.89
0.98
0.25
1.00
0.78
a
Age (years)
Men/women, n (% men)
a
BMI (kg/m2)
Maximal diameter of all cysts (mm)
Volume of all cysts (ml)
Giant cysts, yes/no (% giant)
Perihilar/peripheral location of the cyst
Single/multiple cysts, n
a
Cholesterol (mmol/l)
a
Triglyceride (mmol/l)
b
LDL-cholesterol (mmol/l)
b
HDL-cholesterol (mmol/l)
a
Creatinine (mmol/l)
Urea (mmol/l)
Proteinuria, yes/no
Diabetes mellitus, yes/no
HDL, high-density lipoprotein; LDL, low-density lipoprotein.
a
Mean SD. b Median (interquartile range).
kg/m2 during the study period. There were no differences
in age (P ¼ 0.17), sex (P ¼ 0.17), BMI (P ¼ 0.94), serum
cholesterol (P ¼ 0.65), serum high-density lipoprotein
(P ¼ 0.89), serum creatinine (P ¼ 0.98), prevalence of
proteinuria (P > 0.95) and diabetes mellitus (P ¼ 0.78)
between the hypertensive and nonhypertensive group
of patients. The values of serum creatinine and urea were
normal in all patients (Table 1).
The prevalence of hypertension was 24.1% under the
age of 45 years and increased to 31.5% in the age between
45 and65 years and41.3% over theage of 65 years (P ¼ 0.08).
Patients with hypertension had significantly higher
maximal diameter (P ¼ 0.007) and volume (P ¼ 0.01)
of the cysts than their controls. There were 34 of
62 (55%) giant renal cysts among hypertensive and 29 of
122 (24%) among nonhypertensive patients (P ¼ 0.0001)
(Table 1).
The prevalence of giant cysts was 13.8% under the age
of 45 years and increased to 34.8% in the age between
45 and 65 years and 42.8% over the age of 65 years
(P ¼ 0.009) (Fig. 1). The prevalences of the multiple-cyst
group and the peripheral-cyst group were similar to those
in the single-cyst group and the perihilar-cyst group in
hypertensive and nonhypertensive groups, respectively
(Table 1).
The differences in SBP, DBP and MBP were also significant between pretreatment readings and after 3 days,
1 month, 3 months and 6 months in all hypertensive
patients categorized by cysts’ size, location and number
(P < 0.001) (Fig. 3). There were significantly less hypertensive patients 3 days after treatment than before the
treatment (P < 0.0001) [Fig. 4 (a) and (b)]. Fourteen
patients with giant cysts (four between hypertensive
patients) had recurrences of the cyst, which required
additional treatment. Additional treatment was applied
only to patients with giant cysts.
Discussion
Our series presents an apparent association between the
size of simple renal cysts and hypertension (Table 1) and
suggests that aspiration of cysts results in a reduction of
BP (Figs 2–4). The presence of one or more cysts totally
surrounded by renal parenchyma or location of cysts
showed no association with BP (Table 1).
Fig. 1
100
P = 0.009*
90
80
70
%
60
SBP geometric means [95% confidence interval (CI)]
before cyst evacuation and after 3 days, 1 month, 3 months
and 6 months were 159 (155–162), 147 (142–151),
147 (143–151), 147 (143–151) and 149 (145–153), respectively (P < 0.001). DBP geometric means (95% CI) before
cyst evacuation and after 3 days, 1 month, 3 months and
6 months were 101 (98–102), 93 (91–96), 94 (91–96),
94 (91–96) and 95 (92–97), respectively (P < 0.001).
MBP geometric means (95% CI) before cyst evacuation
and after 3 days, 1 month, 3 months and 6 months were
120 (117–122), 111 (108–114), 112 (109–115), 112 (109–
115) and 113 (110–116), respectively (P < 0.001) (Fig. 2).
Giant cyst
Yes
No
50
40
30
20
10
0
< 45
45−65
> 65
Age strata
The prevalence of giant cysts by age strata.
Copyright © Lippincott Williams & Wilkins. Unauthorized reproduction of this article is prohibited.
Simple renal cysts and arterial hypertension Zerem et al.
Fig. 2
160
hypertensive and nonhypertensive patients to identify
the cysts responsible for an increased BP. The main
shortcoming of those studies was in their design, that
is, whether the groups of patients with or without hypertension differed in variables other than the presence or
absence of cysts.
P < 0.0001
SBP
150
2077
140
130
In several studies, the prevalence of simple renal cysts,
their number and size increased with age [1–6,14], as
does arterial BP, and it has been questioned whether
there might be a causal association between them [2,6].
All patients in our study had simple renal cysts, and the
size of cysts increased with aging (Fig. 1). Consistent with
the previous reports [1,6,15], we also found that simple
renal cysts were more prevalent in men.
P < 0.0001
120
MBP
110
P < 0.0001
100
DBP
90
Before
3 days
intervention
1 month 3 months
6 months
Blood pressure changes in 62 hypertensive patients before and after
treatment. 3 days, 3 days after intervention; 1 month, 1 month after
intervention; 3 months, 3 months after intervention; 6 months, 6 months
after intervention; DBP, diastolic blood pressure; MBP, mean blood
pressure; SBP, systolic blood pressure.
To our knowledge, this is the first study to describe the
association between BP and renal cysts in a relatively
large series of patients who underwent percutaneous
treatment of simple renal cysts. Other studies [1,6,7,9–
11] mostly determine the prevalence of renal cysts in
In our study, the association was found between the size
of the cyst and hypertension, unlike between the location
and number of cysts with hypertension. The mechanism
by which the presence of simple renal cyst is related to
hypertension is still not clear. Some authors [6,7] consider
that perihilar cysts cause increased renin release. The
renin–angiotensin–aldosterone system can be stimulated in hypertensive patients with simple renal cysts,
and it is possible that an increased release of renin from
renal ischemia caused by cyst expansion may explain the
hypertension in those patients.
Fig. 3
119
109
110
110
112
g
115
116
116
116
ng
114
112
115
110
111
111
104
105
105
125
126
126
Blood pressure (stacked)
122
123
119
114
132
Before
intervention
3 days
1 month
3 months
113
ph
113
pp
106
s
127
m
6 months
Changes of mean blood pressure in 62 hypertensive patients before
and after treatment by cysts’ number, location and size (P < 0.001). 3
days, 3 days after intervention; 1 month, 1 month after intervention; 3
months, 3 months after intervention; 6 months, 6 months after
intervention; g, giant cysts; m, multiple cysts; ng, no giant cysts; ph,
perihilar cysts; pp, peripheral cysts; s, single cysts.
The other explanation why simple renal cyst was related
to hypertension might be that the loss of nephrons along
with aging was involved in both development of hypertension and formation of peripheral renal cyst. The loss of
nephron increases workloads of tubules and may cause
hypertrophy and hyperplasia of tubular cells to the extent
of causing cyst formation [16–19]. In this study, neither
the location nor number of cysts was related to hypertension (Table 1).
In our study, the size was an important characteristic of
cysts related to hypertension, but we provided no evidence that large renal cyst could compress the renal
vasculature or increase plasma renin activity. On the
basis of design of our study, we also cannot ascertain
whether individuals with giant renal cysts have reduced
number of nephrons compared with the others.
Some authors [6,7] describe an apparent association
between the presence of simple renal cysts and hypertension and quote previous studies [9], suggesting that
aspiration or surgical removal of cysts results in a
reduction in BP. Our study showed that 3 days after cyst
evacuation, SBP, DBP and MBP decreased significantly.
The significant difference remained on the follow-ups
after 1, 3 and 6 months.
There are several limitations to our study. It describes
only moderately large and giant symptomatic simple
Copyright © Lippincott Williams & Wilkins. Unauthorized reproduction of this article is prohibited.
2078 Journal of Hypertension
2009, Vol 27 No 10
Fig. 4
(a)
(b)
140
Number of patients
140
100
P < 0.0001*
100
0
P < 0.0001*
0
NT before
treatment
HT before
treatment
NT before
treatment
HT before
treatment
HT 3 days
after treatment
0
33
0
30
NT 3 days
after treatment
122
29
122
32
Difference in the number of hypertensive patients before and after treatment. (a) Systolic blood pressure readings, (b) diastolic blood pressure
readings. HT, hypertensive patients; NT, normotensive patients.
renal cysts and their association with BP. We have no
explanation why hypertension did not decrease in about
30% patients (19/62) after percutaneous treatment of
the cysts because we did not evaluate other reasons of
hypertension. Several patients took the same antihypertensive drugs before and after percutaneous treatment
because there was no BP drop in more than 10–15% after
treatment, and all of them remained hypertensive according to referent criteria [20]. We did not measure renal
vein renin concentrations in patients with renal cysts
and hypertension. Furthermore, some cysts during the
follow-up recurred (four cysts in hypertensive patients)
and required additional treatment.
In conclusion, our findings highlight the relationship
between the size of simple renal cysts and arterial hypertension and point out the reduction in BP after aspiration of cysts. Location and number of cysts were not
related to BP.
Acknowledgement
There are no conflicts of interest.
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