Risk factors for postoperative renal function decline after laparoscopic adrenalectomy in patients with primary aldosteronism: a retrospective cohort study

Introduction

Primary aldosteronism (PA) is a condition in which the adrenal cortex secretes excessive amounts of aldosterone from certain adrenal lesions. Aldosterone stimulates sodium reabsorption, contributing to secondary hypertension in 6–11% of patients, increasing renal perfusion pressure, inducing glomerular hyperfiltration, and, with prolonged exposure, leading to decreased kidney function (1). Moreover, prolonged exposure to elevated aldosterone levels contributes to endothelial dysfunction and heightened vascular resistance, ultimately resulting in a decline in estimated glomerular filtration rate (eGFR) (2). Plasma aldosterone concentration (PAC) was strongly correlated with lower eGFR and higher early kidney damage biomarker in PA patients (3).

Previous research has shown that patients with PA experience a significant decrease in eGFR, which is subsequently followed by a reduction in serum aldosterone levels after undergoing unilateral adrenalectomy (1,2,4). Furthermore, some studies suggest that chronic elevation of aldosterone levels before surgery leads to glomerular hyperfiltration, potentially masking underlying kidney dysfunction (5). In addition, hypertension and hypokalemia commonly improve after surgery in patients with PA; however, renal function often remains unchanged and, in some cases, deteriorates (6).

Accurately assessing renal function in patients with PA is challenging, as mild renal impairment may be masked by glomerular hyperfiltration and aldosterone escape (1,7). Following adrenalectomy, serum aldosterone levels decrease, eliminating both glomerular hyperfiltration and aldosterone escape (7). Consequently, a decline in eGFR may occur (1) and reduced eGFR has been associated with an increased risk of mortality, cardiovascular events, and hospitalization (8).

Although several studies have examined renal function changes following adrenalectomy, knowledge gaps remain regarding the risk factors for postoperative renal function decline. One study identified several factors associated with postoperative eGFR reduction in patients with PA, including older age, longer duration of hypertension, lower preoperative serum potassium levels, higher preoperative eGFR, and elevated serum uric acid levels (9). Additionally, Stahl et al. reported that older age, 1-month eGFR decline <60 mL/min/1.73 m², and lateralization index >30 from adrenal vein sampling test were associated with eGFR decline <60 mL/min/1.73 m² at 12 months after PA surgery (10).

Despite these findings, predicting which patients will experience renal function decline after adrenalectomy remains challenging. Variability in study populations, definitions of renal impairment, and follow-up durations contributes to inconsistencies in identifying universal risk factors. Moreover, the complex interplay of factors such as preoperative blood pressure control or individual patient comorbidities makes it difficult to establish a standardized predictive model.

Therefore, this study aims to compare preoperative and postoperative eGFR at 6 months after adrenalectomy and to identify key factors contributing to renal function decline. Understanding these factors may help refine preoperative risk stratification and optimize postoperative monitoring strategies, ultimately improving long-term renal outcomes in patients with PA. We present this article in accordance with the STROBE reporting checklist (available at https://gs.amegroups.com/article/view/10.21037/gs-2026-1-0054/rc) (11).

Methods

Study design and setting

A retrospective cohort study was conducted by reviewing the medical records of patients diagnosed with PA who underwent laparoscopic adrenalectomy at King Chulalongkorn Memorial Hospital between July 2003 and January 2025.

Inclusion and exclusion criteria

All patients diagnosed with PA who underwent laparoscopic adrenalectomy, regardless of age limit. Patients with end-stage renal disease (ESRD), those undergoing bilateral adrenalectomy, individuals with contraindications to laparoscopic surgery, and those with incomplete baseline or follow-up data were excluded. Our surgical techniques have been described previously (12).

Renal function decline (eGFR decline) was defined as a ≥25% reduction in eGFR at 6 months postoperative compared with preoperative.

Sample size

We aimed to include all patients who met the inclusion criteria during the study period. A total of 394 patients underwent laparoscopic adrenalectomy. After excluding 47 patients with missing or incomplete data on postoperative renal function in the earlier years of the study, 347 patients were included in the final analysis.

Diagnosis of PA

PA was diagnosed using the aldosterone-to-renin ratio (ARR): an ARR >30 with PAC >20 ng/dL, or ARR >20 with PAC >15 ng/dL. Confirmatory tests for PA were performed using a saline loading test, where intravenous saline infusion was used to assess aldosterone suppression (13). The location of adrenal tumors was determined by computed tomography (CT) or magnetic resonance imaging (MRI). The adrenal vein sampling test was performed in patients with equivocal imaging results. Pathological confirmation was obtained for all cases.

Data collection

Medical records were independently reviewed by two researchers. Any discrepancies were resolved through consensus or by consultation with a third researcher. The following preoperative data were collected:

• Demographic data: age, sex, and body mass index (BMI).
• Comorbidities: hypertension, diabetes mellitus (DM), chronic kidney disease (CKD), and coronary heart disease (CHD).
• Hypertension characteristics: duration of hypertension, number of antihypertensive medications.
• Clinical laboratory data: serum potassium, blood urea nitrogen (BUN), serum creatinine, eGFR, PAC, plasma renin activity (PRA), and ARR.
• eGFR values: Modification of Diet in Renal Disease Thai (MDRD-Thai) was used to calculate eGFR values.
• Post-operative data at 6 months: serum creatinine levels were measured and used to calculate postoperative eGFR.

Ethical statement

The study was conducted in accordance with the Declaration of Helsinki and its subsequent amendments. The study was approved by the Ethics Committee of the Faculty of Medicine, Chulalongkorn University (IRB No. 238/62). Informed consent was waived in this retrospective study.

Statistical analysis

Descriptive statistics were used to summarize demographic and clinical characteristics. Categorical variables were reported as frequencies and percentages. Continuous data were reported as means with standard deviations (SDs).

The Wilcoxon signed-rank test was used to compare preoperative and postoperative eGFR values. Spearman’s rho was used to assess correlations between various factors and changes in eGFR.

Factors with a P value ≤0.05 in univariate analysis were included in the multivariate logistic regression model to identify independent predictors of postoperative renal function decline.

A P value of ≤0.05 was considered statistically significant for all analyses. All statistical analyses were conducted using SPSS version 23.

Results

Overall renal function changes

A total of 347 patients were included in the study. Following adrenalectomy, 251 patients (72.3%) experienced a decline in eGFR ≥25% (eGFR decline group). The mean eGFR significantly decreased from 87.7 (26.8) mL/min/1.73 m² preoperatively to 79 (26.6) mL/min/1.73 m² at 6 months postoperatively (P<0.001). Similarly, serum creatinine levels increased from 0.96 (0.7) mg/dL preoperatively to 1.1 (0.6) mg/dL at 6 months postoperatively (P<0.001, Table 1, Figure 1).

Figure 1 Compare renal function between pre- and post-operation using box plot. eGFR, estimated glomerular filtration rate.

Comparison between eGFR decline and non-decline groups

Patients were categorized into two groups: those with preserved renal function (n=96, 27.7%) and those with postoperative eGFR decline ≥25% (n=251, 72.3%) (Table 2). Regarding demographic data, both groups had similar mean ages (50.6 vs. 51.9 years) and BMI levels (26.1 vs. 26.6 kg/m²). A slightly higher proportion of females was in the non-decline group (61.5% vs. 56.6%).

About comorbidities, the prevalence of CHD was higher in the decline group (10% vs. 3.1%), while DM and CKD were comparable between groups. In terms of hypertension characteristics, the eGFR decline group had a higher number of antihypertensive medications (mean: 2.3 vs. 2), and almost all patients had hypertension (92.4% vs. 90.6%).

For laboratory data, patients with eGFR decline group had a higher mean preoperative eGFR (89.5 vs. 82.9 mL/min/1.73 m²) and lower potassium levels (3.2 vs. 3.5 mmol/L). In addition, the eGFR decline group had a higher mean ARR (405.9 vs. 247.6) and PAC (52.1 vs. 35.7 ng/dL; Table 2, Figure 2).

Figure 2 Compare renal function after adrenalectomy between non-decline and decline groups using box plot. eGFR, estimated glomerular filtration rate.

Predictors of postoperative renal function decline

Univariate analysis identified the number of antihypertensive medications (P=0.007), CHD (P=0.04), preoperative potassium levels (P=0.001), and baseline eGFR (P=0.01) as significant factors associated with eGFR decline (Table 3). The final multivariate logistic regression model demonstrated a classification accuracy of 72.5%. The Hosmer-Lemeshow goodness-of-fit test results of χ²=9.58 (P=0.30). The multicollinearity diagnostics showed all variables entered into the model had a variance inflation factor <10. The following factors independently predicted postoperative renal function decline: number of antihypertensive drugs [odds ratio (OR) =1.32, 95% confidence interval (CI): 1.03–1.69, P=0.03]; CHD (OR =4.27, 95% CI: 1.21–15.1, P=0.02); lower preoperative potassium levels (OR =0.65, 95% CI: 0.44–0.96, P=0.03); higher baseline eGFR (OR =1.02, 95% CI: 1–1.03, P=0.01).

In addition, the probability equation, presenting probability of patients to be classified into declined group compared to not declined group of renal function loss by using factors from univariate test, was as follows:

Probability=exp(1.567+0.279∗NumberofantiHTdrug−1.452CHD−0.429potassium+0.02PreopeGFR)1+exp(1.567+0.279∗NumberofantiHTdrug−1.452CHD−0.429potassium+0.02PreopeGFR)[1]

Discussion

Previous research on renal impairment in patients with PA suggests that excessive aldosterone secretion induces glomerular hyperfiltration and the aldosterone escape phenomenon, which help maintain eGFR while masking underlying renal function decline and structural damage (7,8). Kuo et al. reported that untreated PA patients exhibit greater relative glomerular hyperfiltration than those with essential hypertension (13). Following adrenalectomy, serum aldosterone levels normalize; however, renal function decline may still occur and persist. Identifying patients at risk for postoperative renal impairment is therefore crucial for optimizing long-term renal outcomes.

In this study, eGFR significantly decreased from 87.7 mL/min/1.73 m² preoperatively to 79 mL/min/1.73 m² postoperatively, which is consistent with previous studies (14-16). According to Kim et al., 32.6% patients developed CKD (new onset eGFR <60 mL/min/1.73 m²) after adrenalectomy (9). Similarly, Utsumi et al. reported that 13% of patients with PA developed new-onset eGFR <45 mL/min/1.73 m² (stages 3b and 4) after surgery, although no patients progressed to ESRD (16). More recently, Stahl et al. found a median eGFR declined 18.2% and 20% at 1 and 12 months, respectively, after surgery (10). These findings highlight the importance of preoperative risk stratification to identify patients at higher risk of renal function decline. Given that a substantial proportion of patients experience postoperative eGFR reduction, routine preoperative renal function assessment should be considered, especially for individuals with preexisting comorbidities such as hypertension, CHD, or baseline kidney dysfunction.

Meta-analysis from He et al. showed old age, high systolic blood pressure, baseline hypokalemia, and low preoperative eGFR were increased risk of eGFR decrease after adrenalectomy in PA patients (17). Our study identifies key risk factors for postoperative renal function decline, eGFR reduction ≥25% at 6 months postoperatively, including the number of antihypertensive medications, CHD, lower preoperative potassium levels, and higher preoperative eGFR. While our findings are aligned with previous studies, some variations exist, which are explored below.

First, we found that the number of antihypertensive medications increases the risk of postoperative renal function declining. Previous studies have suggested that patients requiring multiple antihypertensive drugs often have more advanced hypertension and vascular remodeling, which may contribute to renal function decline (18). The higher burden of antihypertensive therapy may indicate greater preexisting renal damage, making these patients more susceptible to postoperative eGFR reduction (18,19). Kim et al. also reported that long-standing hypertension was a significant predictor of renal function decline after adrenalectomy (9). Our findings suggest that patients on multiple antihypertensive agents should be considered at higher risk for postoperative renal impairment, necessitating closer renal function monitoring.

Second, our study identified CHD as an independent risk factor for postoperative renal function decline, reinforcing the strong link between cardiovascular and renal dysfunction. A previous study found that hospitalization for cardiac diseases, including CHD, was associated with accelerated eGFR decline, while clinical atherosclerosis and subclinical cardiovascular disease contributed to kidney function deterioration, likely due to renal atherosclerosis (20). These findings suggest that preexisting cardiovascular disease may predispose patients to postoperative renal impairment, emphasizing the need for closer renal monitoring, cardiovascular risk optimization, and nephroprotective strategies in patients with CHD undergoing adrenalectomy.

Third, similar to Kim et al., we found that low serum potassium levels increase the risk of renal function decline (9). This finding is further supported by previous studies that have demonstrated a correlation between baseline potassium levels and postoperative eGFR changes (7,15). Recently, Qin et al. found that the PA patient with hypokalemia had a significantly higher level of 24-hour urine microalbumin and albumin-to-creatinine ratio than the normokalemia group (21). Clinically, this underscores the importance of preoperative potassium correction, as optimizing potassium levels may help mitigate renal function decline following adrenalectomy. Also, this finding suggests that close monitoring and early potassium supplementation should be considered for high-risk patients to improve postoperative renal outcomes.

Fourth, our findings are consistent with Catena et al., who reported a direct correlation between eGFR and PAC and an inverse correlation with PRA (22). This suggests that aldosterone-induced hyperfiltration may mask underlying kidney dysfunction, which becomes apparent after surgery. Furthermore, Lu et al. found the patient with high preoperative eGFR ≥90 mL/min/1.73 m² were increased risk of eGFR decline at 12 months after adrenalectomy (23). However, our study couldn’t demonstrate the association between PAC and the eGFR decline group. The preoperative and postoperative 6-month PAC weren’t significant difference between groups (P=0.09 and 0.35, respectively). Clinically, this reinforces the need for careful interpretation of preoperative eGFR values, as a seemingly normal eGFR may not reflect true renal reserve. Patients with high PAC and suppressed PRA may require more intensive renal monitoring after adrenalectomy to detect and manage potential kidney function decline early.

Lastly, unlike the previous literatures, we did not find a significant association between age and renal function decline, which may be due to differences in population characteristics (9,10). However, our finding was comparable with the study from Ma et al. that long term eGFR decline was not different among the age groups (24). This discrepancy highlights the importance of individualized risk assessment, as the impact of age on renal outcomes may vary across different patient cohorts.

This study had some limitations. Firstly, this is a retrospective descriptive study that may introduce selection bias. Moreover, proteinuria was assessed using a dipstick test, and urine albumin excretion was not measured, which may have limited our ability to comprehensively evaluate renal damage. Additional factors that may impact postoperative renal function, for example, types of antihypertensive medication, perioperative hemodynamic, and postoperative blood pressure control, weren’t included in the study. Due to our long study period, the management of hypertension in different eras may impact the number and type of antihypertensive medications. Despite these limitations, our findings highlight the importance of postoperative renal function monitoring in patients with PA undergoing adrenalectomy. Future studies with prospective designs and more comprehensive data collection are needed to validate these results and improve clinical management strategies.

Conclusions

This study identifies key risk factors for postoperative renal function decline, including the number of antihypertensive medications, CHD, lower preoperative potassium levels, and higher preoperative eGFR. These findings underscore the need for comprehensive preoperative risk assessment and close postoperative renal monitoring, particularly in patients with multiple antihypertensive medications or cardiovascular comorbidities. Optimizing potassium levels before surgery and recognizing the potential masking effect of hyperfiltration on renal function are crucial for early intervention. Integrating these considerations into clinical practice may help mitigate renal impairment and improve long-term kidney outcomes following adrenalectomy.

Acknowledgments

None.

Footnote

Reporting Checklist: The authors have completed the STROBE reporting checklist. Available at https://gs.amegroups.com/article/view/10.21037/gs-2026-1-0054/rc

Data Sharing Statement: Available at https://gs.amegroups.com/article/view/10.21037/gs-2026-1-0054/dss

Peer Review File: Available at https://gs.amegroups.com/article/view/10.21037/gs-2026-1-0054/prf

Funding: None.

Conflicts of Interest: All authors have completed the ICMJE uniform disclosure form (available at https://gs.amegroups.com/article/view/10.21037/gs-2026-1-0054/coif). The authors have no conflicts of interest to declare.

Ethical Statement: The authors are accountable for all aspects of the work in ensuring that questions related to the accuracy or integrity of any part of the work are appropriately investigated and resolved. The study was conducted in accordance with the Declaration of Helsinki and its subsequent amendments. The study was approved by the Ethics Committee of the Faculty of Medicine, Chulalongkorn University (IRB No. 238/62). Informed consent was waived in this retrospective study.

Open Access Statement: This is an Open Access article distributed in accordance with the Creative Commons Attribution-NonCommercial-NoDerivs 4.0 International License (CC BY-NC-ND 4.0), which permits the non-commercial replication and distribution of the article with the strict proviso that no changes or edits are made and the original work is properly cited (including links to both the formal publication through the relevant DOI and the license). See: https://creativecommons.org/licenses/by-nc-nd/4.0/.

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