Advances in Peritoneal Dialysis, Vol. 30, 2014
Berna Yelken,1 Numan Gorgulu,1 Meltem Gursu,2 Halil
Yazici,1 Yasar Caliskan,1 Aysegul Telci,3 Savas Ozturk,2
Rumeyza Kazancioglu,4 Tevfik Ecder,1 Semra Bozfakioglu1
There is increasing evidence that long-term peritoneal dialysis (PD) is associated with structural
changes in the peritoneal membrane. Inhibition of the
renin–angiotensin system has been demonstrated to
lessen peritoneal injury and to slow the decline in residual renal function. Whether spironolactone affects
residual renal function in addition to the peritoneal
membrane is unknown.
We evaluated 23 patients (13 women) with a
glomerular filtration rate of 2 mL/min/1.73 m2 or
more who were receiving PD. Patients with an active infection or peritonitis episode were excluded.
Baseline measurements were obtained for serum
high-sensitivity C-reactive protein (hs-CRP), vascular endothelial growth factor (VEGF), transforming growth factor β (TGF-β), and connective tissue
growth factor (CTGF); for daily ultrafiltration (in
milliliters); for end-to-initial dialysate concentration of glucose (D4/D0 glucose), Kt/V, and peritoneal
transport status; and for dialysate cancer antigen 125
(CA125). Spironolactone therapy (25 mg) was given
daily for 6 months, after which all measurements
were repeated.
Mean age of the patients was 46 ± 13 years. Duration of PD was 15 ± 21 months (range: 2 – 88 months).
After spironolactone therapy, mean dialysate CA125
was significantly increased compared with baseline
(20.52 ± 12.06 U/mL vs. 24.44 ± 13.97 U/mL, p =
0.028). Serum hs-CRP, VEGF, TGF-β, CTGF, daily
ultrafiltration, D4/D0 glucose, Kt/V, and peritoneal
From: 1Division of Nephrology, Department of Internal
Medicine, Istanbul Faculty of Medicine; 2Division of Nephrology, Department of Internal Medicine, Haseki Education and Research Hospital; 3Department of Biochemistry,
Faculty of Medicine, Istanbul University; and 4Division of
Nephrology, Faculty of Medicine, Bezmialem Vakif University, Istanbul, Turkey.
Effects of Spironolactone
on Residual Renal Function
and Peritoneal Function in
Peritoneal Dialysis Patients
transport status were similar at both times. At the
end of the study period, residual glomerular filtration
rate in the patients was lower.
In PD patients, treatment with spironolactone
seems to slow the decline of peritoneal function,
suppress the elevation of profibrotic markers, and
increase mesothelial cell mass.
Key words
Spironolactone, residual renal function, peritoneal
function
Introduction
Long-term peritoneal dialysis (PD) is accompanied
by alterations in the peritoneal membrane (1–3)
because of continuous exposure to bioincompatible components of dialysis solution and repeated
episodes of peritonitis (4). The characteristic feature
of peritoneal damage in PD is declining ultrafiltration (UF) capacity, associated with submesothelial
fibrosis, accumulation of extracellular matrix, and
neoangiogenesis (5).
Activation of the renin–angiotensin–aldosterone
system (RAAS) initiates a process mediated by the
cytokine transforming growth factor β (TGF-β),
which ends with tissue repair (6–8). Angiotensin converting-enzyme inhibitors (ACEIs) and angiotensin II
receptor blockers (ARBs) have been shown to prevent
peritoneal membrane damage (9–11). Clinical and
experimental data support the hypothesis that mineralocorticoid receptor antagonists might improve the
prognosis of patients with kidney injury (12,13). In an
experimental study, irbesartan, spironolactone, and
irbesartan plus spironolactone were found to moderate peritoneal fibrosis in rats with bacterial peritonitis
compared with uninfected control rats (14). However,
whether aldosterone blockade is useful in preventing
peritoneal fibrosis and preserving peritoneal function
in patients on PD is not yet completely understood.
6
Spironolactone, RRF, and Peritoneal Function in PD
Residual renal function (RRF) is the major
determinant of morbidity and mortality in patients
on PD (15,16). It contributes to measures of dialysis
adequacy and creatinine clearance (17,18) and accounts for most of the variability in the requirement
for dialysis (19). Although ACEIs and ARBs have
been shown to slow the decline in RRF (20,21), the
usefulness of aldosterone blockade in preserving RRF
in patients on PD is unknown.
In the present study, we aimed to evaluate the
protective effects of spironolactone on peritoneal
function and RRF in PD patients.
of glucose, blood urea nitrogen, creatinine, sodium,
potassium, calcium, phosphorus, total protein, albumin, triglycerides, total cholesterol, and low-density
and very-low-density lipoprotein cholesterol were
measured by standard enzymatic methods. Highsensitivity C-reactive protein (hs-CRP) was measured by the nephelometric method (Dade Behring,
Deerfield, IL, U.S.A.). For measurements of serum
vascular endothelial growth factor (VEGF), TGF-β,
and connective tissue growth factor (CTGF), blood
samples were centrifuged at 4000 cycles per second for
5 minutes. The supernatant was stored at –80°C until
determinations were made by enzyme-linked immunosorbent assay using a commercial kit (Invitrogen,
Camarillo, CA, U.S.A.). Renal and peritoneal urea and
creatinine clearances were measured in 24-hour urine
and dialysate collections. Simultaneous serum urea
and creatinine determinations were obtained during
the collection period. Residual GFR was defined as
the average of the 24-hour urinary urea and creatinine
clearances (18). Weekly Kt/V was used to estimate the
dialysis dose. Peritoneal function—including daily UF
(in milliliters) and glucose transport [(4-hour) end-toinitial dialysate ratio of glucose (D4/D0 glucose)]—
were examined in a standard peritoneal equilibration
test using dialysate containing 2.5% glucose.
The cancer antigen 125 (CA125) concentration
in the 24-hour peritoneal effluent collection was
measured by electrochemiluminescence assay (Elecys CA125 II kit with an Elecsys 2010 immunoassay
analyzer: Roche Diagnostics, Mannheim, Germany).
After 6 months, all measurements were repeated.
Patient examinations conformed to good medical and
laboratory practices and to the recommendations of
the Declaration of Helsinki on biomedical research
involving human subjects. The Istanbul School of
Medicine Clinical Studies Board approved the study.
Methods
Patients
Our study enrolled 30 adult patients between 18 and
70 years of age who had been on PD for at least 3
months, who had a glomerular filtration rate (GFR) of
2 mL/min/1.73 m2 or more, and who had no history of
taking an ACEI or ARB for at least 6 months. Patients
were excluded from the study if they had an underlying medical condition (such as congestive heart
failure) that mandates therapy with an ACEI or ARB,
hyperpotassemia (serum potassium > 5.5 mmol/L),
or an active infection or a peritonitis episode within
the preceding month.
Information on age, sex, body mass index, blood
pressure, cause of end-stage renal failure, and time
spent on PD were gathered from patient records.
Spironolactone therapy (25 mg) was given daily for
6 months. Patients were evaluated in the outpatient
PD clinic every month. During the study, no major
alterations were made in medications (for example,
phosphate binders, erythropoietin, vitamin D preparations) or dialysis modalities of the patients—except
that patients who required antihypertensive medication were allowed to take agents other than ACEIs
and ARBs. Doses were adjusted appropriately to
achieve and maintain the target blood pressure of
135/85 mmHg or to avoid symptomatic hypotension.
A regular diet containing 1 – 1.2 g/kg protein daily
and limited sodium was recommended throughout
the follow-up period.
Laboratory data
Fasting serum samples for biochemical analysis were
obtained between 0800 h and 0900 h. A complete
blood cell count was performed, and serum levels
Statistical analysis
The statistical analysis was carried out using the
Statistical Package for Social Sciences (version 15.0
for Windows: SPSS, Chicago, IL, U.S.A.). Numerical
variables are presented as mean ± standard deviation.
Variables were compared using the paired-samples
t-test, and p < 0.05 was accepted as significant.
Results
Of the 30 enrolled patients, 7 were eventually excluded (1 because of sterile peritonitis, 1 because of
Yelken et al.
dialysis inadequacy leading to a switch to hemodialysis, and 5 because they stopped spironolactone
treatment). The final study group included 13 women
and 10 men, with a mean age of 46 ± 13 years (range:
21 – 69 years) and a PD duration of 15 ± 21 months
(range: 3 – 88 months). Table I shows the causes of
end-stage renal disease in the patients. The PD modality was continuous ambulatory PD in 20 patients
and continuous cycling PD in 3. Mean blood pressure
was 141 ± 27 mmHg systolic and 89 ± 15 mmHg
diastolic. Table II shows the demographic features of
the patients and the results of their peritoneal functional tests at the end of the study period. Body mass
index and systolic and diastolic blood pressure were
all similar in both periods (Table II). No decline in
peritoneal membrane function (UF, D4/D0 glucose,
Kt/V urea) was observed at the end of the 6 months.
Peritoneal transport characteristics at the baseline and
final (after 6 months of spironolactone therapy) evaluations were divided as follows: high, 2 at baseline,
3 at 6 months; high average, 11 at baseline, 12 at 6
months; low average, 8 at baseline, 6 at 6 months; and
low, 2 at baseline, 2 at 6 months. Residual GFR had
significantly declined by the end of the study period
compared with baseline (5.20 ± 3.10 mL/min vs. 3.90
± 3.22 mL/min, p = 0.006).
Table II shows biochemical results such as glucose, blood urea nitrogen, creatinine, sodium, potassium, calcium, phosphorus, albumin, cholesterol
readings, hs-CRP, and hemoglobin at both evaluations. We observed no statistically significant differences in the values at the end of 6 months compared
with baseline values.
At 6 months, mean dialysate CA125 had significantly increased compared with baseline (20.52
± 12.06 U/mL vs. 24.44 ± 13.97 U/mL, p = 0.028).
Serum profibrotic markers such as VEGF, TGF-β, and
CTGF were similar in the two evaluations (Table III).
Discussion
Long-term PD is associated with structural changes
in the peritoneal membrane. The importance of local
angiotensinogen II in the loss of peritoneal function and of RAAS blockage leading to regression of
that loss has previously been established (10). In an
experimental study, treatment with ACEI reduced
peritoneal thickness and increased UF volume in rats
(9). In human studies, ARB not only preserved RRF,
but also increased peritoneal creatinine clearance 1
7
table i
Causes of end-stage renal disease in the study patients
Cause
Patients [n (%)]
Glomerulonephritis
ADPKD
Pyelonephritis
Primary nephrosclerosis
Unknown or others
TOTAL
5 (21.7)
4 (17.4)
2 (8.7)
2 (8.7)
10 (43.5)
23
ADPKD = autosomal-dominant polycystic kidney disease.
table ii
Patient parameters at baseline and 6 months
Valuea
Parameter
p Value
Baseline
6 Months
Systolic
141±27
136±29
0.232
Diastolic
89±15
86±12
0.165
Blood pressure (mmHg)
Body mass index
(kg/m2)
27±5.1
27±4.9
0.340
Glucose (mg/dL)
111±42
125±62
0.152
BUN (mg/dL)
55±16
65±22
0.148
Creatinine (mg/dL)
7.1±3.3
7.4±2.8
0.457
Sodium (mmol/L)
138±3
136±3
0.130
Potassium (mmol/L)
4.3±0.5
4.4±0.6
0.488
Ca×P
40.2±11.0
43.2±11.9
0.262
Albumin (g/dL)
3.75±0.48
3.69±0.39
0.539
155±80
162±76
0.485
Total
194±37
192±29
0.788
LDL
121±39
115±25
0.567
hs-CRP (mg/L)
10.2±4.0
8.0±3.13
0.176
Hemoglobin (g/dL)
11.1±1.0
10.1±1.2
0.468
0.198
Triglycerides (mg/dL)
Cholesterol (mg/dL)
Total Kt/Vurea
2.7±0.9
2.5±0.7
Ultrafiltration (mL/day)
689±150
710±152
0.539
D4/D0 glucose
0.46±0.29
0.38±0.12
0.207
Residual GFR (mL/min)
5.2±3.10
3.90±3.22
0.006
a Mean ± standard error of the mean.
BUN = blood urea nitrogen; Ca×P = calcium–phosphorus product; LDL = low-density lipoprotein; hs-CRP = high-sensitivity
C-reactive protein; D4/D0 = 4-hour–to–initial dialysate concentration ratio; GFR = glomerular filtration rate.
year after PD initiation (21). The foregoing studies
indicate that the RAAS plays a role in the progression of peritoneal fibrosis, deterioration of UF, and
maintenance of RRF. However, little is known about
the role of mineralocorticoid receptor antagonists in
8
Spironolactone, RRF, and Peritoneal Function in PD
table iii Levels of profibrotic markers and cancer antigen 125
(CA125)
profibrotic markers (VEGF, TGF-β, CTGF) after 6
months of spironolactone treatment, although such
profibrotic markers are usually expected to increase
during the 6-month period after PD start. Note that all
markers were examined in serum; the results might
have been different had the analyses been made in
effluent and tissue samples.
Long-term PD is known to cause alterations in
the peritoneal membrane. Loss of mesothelial cells
is one of those alterations. Dialysate CA125 is a useful marker indicating loss of mesothelial cell mass,
at least with respect to the effect of the cell mass on
mesothelium (25–27). Peritoneal mesothelial cells are
the most likely source for local CA125 release within
the peritoneum because CA125 is almost undetectable in lymphocytes, monocytes, granulocytes, and
fibroblasts (28). Three different studies have found
a relationship between the number of mesothelial
cells in peritoneal effluent from PD patients and effluent CA125 concentration. In addition, a decline in
the appearance rate of CA125 has been established
during longitudinal analysis (29–31), and low CA125
values have been found in patients with peritoneal
sclerosis (32,33). A significant elevation in effluent
CA125 was observed after 6 months of spironolactone
treatment in the present study. Hence, spironolactone
treatment seems to be associated with an increase in
mesothelial cell mass.
Our study has some limitations. First, no control
group was used, and the number of participating
patients was small. We used 25 mg of spironolactone
daily in the study, but higher doses might produce
different results with respect to RRF and profibrotic markers.
Parameter
Valuea
Baseline
In serum
VEGF (pg/mL)
TGF-β (pg/mL)
CTGF (pg/mL)
In dialysate
CA125 (U/mL)
6 Months
325±48
365±60
10047±688 10528±1022
3583±458 3708±685
20.5±2.8
p Value
24.4±3.3
0.535
0.598
0.761
0.028
a Mean ± standard error of the mean.
VEGF = vascular endothelial growth factor; TGF-β = transforming growth factor β; CTGF = connective tissue growth factor.
preventing peritoneal fibrosis and maintaining peritoneal function in PD patients.
To our knowledge, the present trial is the first in
humans on PD to examine the effect of spironolactone
on peritoneal function and RRF. After 6 months of
spironolactone treatment, no significant difference
was observed in profibrotic markers or in parameters
of peritoneal membrane function (UF, Kt/V, D4/D0
glucose), and dialysate levels of CA125, a useful
marker of mesothelial cell mass, increased. In a study
conducted in rats, peritoneal functions including UF,
glucose transport, albumin leakage, and peritoneal
thickening were significantly improved by spironolactone in 14 days of administration (22).
Although our study detected no improvement in
parameters of peritoneal function such as UF, Kt/V,
and D4/D0 glucose, no significant decline in those
parameters occurred after 6 months of spironolactone
treatment either. Spironolactone treatment did not
prevent decline in residual GFR. Because no control
group was used in our study, it is difficult to evaluate
the effect of spironolactone on residual GFR and its
clinical consequences.
An in vitro study that exposed a mesothelial cell
culture to high concentrations of glucose determined
that increased RAAS activation and angiotensinogen II led to an elevation in TGF-β. Evidence from
more than one study has suggested that TGF-β is the
key mediator in the development of fibrosis (6,23).
Our analysis of molecules that might be involved in
peritoneal damage found that spironolactone suppressed inflammatory and fibrotic processes (24). No
significant difference was found in the levels of serum
Conclusions
Spironolactone treatment seems to slow the loss of
peritoneal function, suppress the expected elevation
in profibrotic markers, and increase mesothelial cell
mass in PD patients. However, we were unable to
show a positive effect of spironolactone on RRF.
Disclosures
No financial conflict of interest exists.
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Corresponding author:
Savas Ozturk, md, Haseki Training and Research
Hospital, Department of Nephrology, Istanbul,
Turkey.
E-mail:
savasozturkdr@yahoo.com