Impact of the Four Pillars on Electrolyte Derangements during State-of-the-Art Therapy for Diabetic Kidney Disease

Abstract

The pharmacological management of diabetic kidney disease (DKD) has shifted toward a “four-pillar” approach that offers robust cardiorenal protection. While traditional renin-angiotensin system (RAS) inhibitors carry well-documented electrolyte risks, the distinct electrolyte profiles of novel therapies—sodium-glucose cotransporter-2 (SGLT2) inhibitors, glucagon-like peptide-1 receptor agonists (GLP-1 RAs), and non-steroidal mineralocorticoid receptor antagonists (nsMRAs)—warrant a comprehensive understanding. This review examines these drug-induced electrolyte derangements. SGLT2 inhibitors demonstrate a highly favorable safety profile; despite inducing osmotic diuresis, they are notably associated with a reduced risk of hyperkalemia. Similarly, GLP-1 RAs possess an exceptionally low risk of direct renal electrolyte wasting, with imbalances occurring primarily secondary to severe gastrointestinal intolerance. Conversely, nsMRAs, such as finerenone, introduce a mild risk of hyperkalemia, though their unique receptor selectivity significantly diminishes this risk compared to traditional steroidal mineralocorticoid receptor antagonists. Crucially, combining SGLT2 inhibitors and nsMRAs creates a physiological synergy that attenuates hyperkalemic adverse effects while maximizing antiproteinuric benefits. By integrating these complementary mechanisms alongside routine electrolyte monitoring, clinicians can safely sustain these indispensable combination therapies and optimize clinical outcomes in DKD.

INTRODUCTION

The establishment of the “four-pillar” of pharmacological therapy has reshaped the management of diabetic kidney disease (DKD), rendering a comprehensive understanding of these mechanistically distinct agents essential. In particular, recognizing drug-induced electrolyte imbalances is a critical priority for prescribing clinicians, which, in turn, requires a fundamental grasp of the baseline electrolyte vulnerabilities inherent to the pathophysiology of DKD. The diabetic intrarenal environment is characterized by progressive neurohormonal and structural alterations that predispose patients to severe electrolyte derangements even prior to any pharmacological intervention.

The most prominent pathophysiological hallmark of advanced DKD is hyporeninemic hypoaldosteronism, which clinically manifests as type 4 renal tubular acidosis. Persistent chronic hyperglycemia and microvascular ischemia lead to the hyalinization of the afferent arteriole and subsequent damage to the juxtaglomerular apparatus, impairing renin synthesis and release [1]. Concurrently, autonomic neuropathy and impaired conversion of prorenin to active renin further suppress the renin-angiotensin system (RAS) axis. This deficit in aldosterone-mediated sodium-potassium exchange in the principal cells of the cortical collecting duct directly results in chronic potassium retention [2]. Consequently, DKD patients exhibit a significantly higher propensity for developing hyperkalemia at a much earlier stage of chronic kidney disease (CKD) compared to those with non-diabetic etiologies. This underlying defect drastically narrows the safety margin when introducing standard-of-care cardiorenal therapies.

Advanced DKD accompanied by nephrotic-range proteinuria introduces complex hemodynamic and metabolic shifts that alter electrolyte homeostasis. First, the profound loss of oncotic pressure induces arterial underfilling, triggering secondary hyperaldosteronism and non-osmotic antidiuretic hormone (ADH) release that result in chronic dilutional hyponatremia [3], while acute glycemic spikes concurrently induce transcellular fluid shifts that manifest as hyponatremia. In parallel, massive proteinuria leads to the co-excretion of vitamin D-binding protein, significantly compromising the intrarenal generation of active 1,25(OH)₂D₃ [4,5]. This deficit in active vitamin D, paired with phosphate retention from a declining estimated glomerular filtration rate (eGFR), precipitates hypocalcemia and accelerates secondary hyperparathyroidism. Finally, the combination of heavy proteinuria and osmotic diuresis facilitates substantial urinary magnesium loss, which is worsened by the hyperglycemia-induced downregulation of tubular magnesium transporters [6], thereby establishing a highly vulnerable electrolyte baseline.

Recognizing these multifaceted baseline disturbances is critical, as they form the precarious pathophysiological backdrop against which modern pharmacotherapies operate. By anticipating adverse effects and implementing rigorous monitoring based on a deeper understanding of these medications, clinicians can successfully overcome these electrolyte-related hurdles. Given that RAS inhibitor-induced electrolyte disturbances have been extensively covered in previous literature, this review will focus on the electrolyte imbalances associated with the remaining three therapeutic pillars: sodium-glucose cotransporter-2 (SGLT2) inhibitors, glucagon-like peptide-1 receptor agonists (GLP-1 RAs), and non-steroidal mineralocorticoid receptor antagonists (nsMRAs). The distinct electrolyte profiles and clinical considerations for each class are summarized in Table 1. Furthermore, we explore how combination therapies involving these agents can mitigate electrolyte derangements, ultimately offering patients optimal treatment strategies.

Table 1. Electrolyte profiles and clinical considerations of novel pharmacotherapies in diabetic kidney disease.

Class	Main electrolyte effects	Primary mechanism	Clinical caveats & monitoring
SGLT2 inhibitors	Potassium: Reduced risk of hyperkalemia	Promotes distal sodium delivery and osmotic diuresis, enhancing K+ secretion; augments renal Mg2+ reabsorption.	Generally safe; monitor for volume depletion.
	Magnesium: Mild increase		Clinical vigilance for hypernatremia in acute illness.
GLP-1 RAs	Potassium: Neutral/mild decrease	Low intrinsic renal effect; electrolyte imbalances are typically secondary to GI side effects.	Monitor electrolytes primarily in patients with severe GI intolerance (nausea, vomiting, diarrhea) to prevent secondary dehydration.
	Sodium: Neutral/hyponatremia
nsMRAs (e.g., finerenone)	Potassium: Mild to moderate increase	Antagonizes MR in the distal tubule, reducing ENaC-mediated Na+ reabsorption and K+ excretion.	Lower risk of hyperkalemia than steroidal MRAs due to unique receptor selectivity; requires routine K+ monitoring.
	Sodium: Potential dilutional hyponatremia
Synergistic combination (SGLT2 inhibitors + nsMRA)	Potassium: Attenuated hyperkalemia risk	Physiological Synergy: SGLT2 inhibitors-induced distal Na+ delivery and flow offset the K+-retaining effect of nsMRAs.	The “Ideal Synergy”: Maximizes cardiorenal and antiproteinuric benefits while neutralizing the primary limiting adverse effect (K+).

ENaC, epithelial sodium channel; GI, gastrointestinal; GLP-1 RA, glucagon-like peptide-1 receptor agonist; MR, mineralocorticoid receptor; nsMRA, non-steroidal mineralocorticoid receptor antagonist; SGLT2, sodium-glucose cotransporter-2.

RAS INHIBITORS

Among the four pillars, RAS inhibition serve as the cornerstone of DKD treatment. Agents such as angiotensin-converting enzyme inhibitors (ACEi) and angiotensin II receptor blockers (ARBs) directly confer renoprotection by reducing intraglomerular pressure and proteinuria, addressing specific intrarenal hemodynamic pathways [7,8]. Notably, the landmark Irbesartan Diabetic Nephropathy Trial demonstrated that the renoprotective benefits of irbesartan extend far beyond blood pressure control. Historically, the dual blockade of ACEi and ARBs has not been recommended due to an increased risk of adverse events, primarily hyperkalemia [8]. Today, however, the fear of hyperkalemia rarely deters clinicians from optimizing RAS inhibitor therapy.

Recent meta-analyses have shown that the concurrent use of novel potassium binders, such as patiromer and sodium zirconium cyclosilicate, increases the achievement rate of optimal RAS inhibitor doses by approximately 14% and significantly lowers the risk of hyperkalemia compared to placebo in patients with heart failure and CKD [9]. Furthermore, real-world data indicate that maintaining RAS inhibitor therapy with the strategic aid of these potassium-lowering agents is associated with reduced all-cause mortality and lower hospitalization rates [10,11].

SGLT2 INHIBITORS

SGLT2 inhibitors reduce hyperfiltration and improve metabolic control, exerting renoprotective effects through mechanisms beyond glucose reduction. Clinical studies have demonstrated that SGLT2 inhibitors improve cardiac and renal outcomes in diabetic [12,13,14] and non-diabetic conditions, including CKD [15] and heart failure [16]. Based on these findings, SGLT2 inhibitors have emerged as an important pillar in preventing kidney function decline in patients with DKD. SGLT2 inhibitors block glucose and sodium reabsorption in the kidneys, promote natriuresis, and restore tubuloglomerular feedback, which consequently results in a decrease in glomerular hyperfiltration and albuminuria. Through their unique mechanism of blocking renal tubular channels, SGLT2 inhibitors exert diverse effects beyond reducing blood glucose levels, conferring renal and cardiovascular protective benefits.

Initially, SGLT2 inhibitors were considered to have a relatively neutral profile regarding electrolyte homeostasis. However, as real-world clinical experience has accumulated, distinct electrolyte shifts have become evident. On one hand, the profound glycosuria-induced osmotic diuresis has been reported to cause hypernatremia in certain vulnerable clinical scenarios. On the other hand, early theoretical concerns regarding the potential for SGLT2 inhibitors to induce hyperkalemia have been largely alleviated. In fact, clinical evidence indicates a lower incidence of hyperkalemia and occasionally even the occurrence of mild hypokalemia associated with their use. This unexpected potassium-lowering tendency has proven to be a significant clinical advantage; it effectively offsets the hyperkalemic risks associated with RAS inhibitors, thereby permitting the safe and sustained concurrent use of these foundational therapies in clinical practice.

Water-sodium balance

Hypernatremia primarily arises from glucosuria-induced osmotic diuresis, which promotes renal free-water clearance. Although SGLT2 inhibitors initially acutely induce osmotic diuresis and mild volume contraction, they rarely lead to hypernatremia due to robust physiological compensatory mechanism. The initial volume depletion activates the body’s water conservation system, leading to a significant accumulation of urea in the renal medulla [17]. The resulting elevation in medullary osmolality establishes a potent osmotic gradient that facilitates free-water reabsorption into the systemic circulation. Owing to this urea-driven renal water conservation, the baseline risk of hypernatremia remains inherently low during SGLT2 inhibitor therapy. Nevertheless, clinicians must remain vigilant during intercurrent illnesses (often termed ‘sick days’) characterized by acute gastrointestinal fluid losses or when voluntary water intake is severely restricted. In such vulnerable states, these compensatory mechanisms can be easily overwhelmed, predisposing patients to profound volume depletion and subsequent electrolyte derangements.

Recently, SGLT2 inhibitors have emerged as a promising and safe off-label treatment modality for the syndrome of inappropriate antidiuresis (SIAD). By inducing glycosuria and subsequent osmotic diuresis, these agents promote aquaresis—the excretion of solute-free water—thereby effectively elevating serum sodium levels. Consequently, they are increasingly considered a viable pharmacological alternative or adjunct to traditional fluid restriction.

The current evidence base, though limited to two small-scale randomized controlled trials (RCTs), supports their therapeutic potential. These agents have demonstrated significant efficacy in raising serum sodium concentrations compared to placebo in both acute hospitalized settings [18] and chronic outpatient scenarios [19]. Furthermore, they proved effective when combined with varying degrees of fluid restriction, ranging from standard limitation (< 1,000 mL/day) to more liberal regimens (1,500–1,600 mL/day). Importantly, SGLT2 inhibitors were well-tolerated in these SIAD cohorts, with no reported incidences of hypoglycemia or clinically significant hypotension.

Despite these promising preliminary data, several limitations warrant caution. The current evidence is restricted by small sample sizes, short study durations, and modest absolute efficacy, yielding placebo-subtracted sodium increases of only 3.0–4.1 mmol/L. Additionally, the safety of combining SGLT2 inhibitors with strict fluid restriction (< 500 mL/day) remains unknown, and their use in acute settings carries a potential risk of overly rapid sodium correction and transient renal impairment [18].

Beyond these clinical concerns, a critical practical caveat limits their immediate translation into real-world clinical practice. Both aforementioned RCTs utilized empagliflozin at a dose of 25 mg daily to treat SIAD. In contrast, the standard approved dosage for primary indications such as DKD and heart failure in real-world practice is typically 10 mg. Given this significant dosage discrepancy, extrapolating the safety and efficacy profiles of the 25 mg trial dose to routine clinical care warrants careful consideration. Until large-scale investigations validate the efficacy of the standard 10 mg dose in this context, the off-label prescription of SGLT2 inhibitors for SIAD should be approached with caution.

Potassium derangement

A core renoprotective mechanism of SGLT2 inhibitors involves afferent arteriolar vasoconstriction, which effectively mitigates glomerular hyperfiltration. This hemodynamic adjustment typically results in a transient reduction in the eGFR within the first 2 to 4 weeks of treatment initiation—a clinical phenomenon widely recognized as the “initial dip.” Historically, this acute decline prompted significant concern regarding a potential impairment in renal potassium excretory capacity. Given that many patients with DKD already exhibit compromised potassium homeostasis and are frequently prescribed concurrent RAS inhibitors, there was a rational clinical suspicion that this initial dip might precipitate life-threatening hyperkalemia.

These early apprehensions were reinforced by initial data, particularly from trials involving canagliflozin, which reported a modest increase in hyperkalemic episodes among patients with moderate-to-severe renal impairment or those on concomitant RAS inhibitors [20]. This observation even led to an official Food and Drug Administration label warning. However, these concerns were effectively dispelled with the publication of the CANVAS program and subsequent trials. Comprehensive analyses demonstrated no clinically meaningful differences in serum potassium levels between the canagliflozin and placebo groups, regardless of dose, baseline eGFR, or concomitant RAS inhibitor use [21]. Furthermore, recent meta-analyses have shown that SGLT2 inhibitors are associated with a lower risk of hyperkalemia [22], particularly in patients with DKD who concurrently receive RAS inhibitors or mineralocorticoid receptor antagonists (MRAs) [23].

Several mechanisms have been proposed to explain how SGLT2 inhibitors mitigate hyperkalemia risk despite the initial dip in eGFR. As detailed in a recent physiological review [24], these agents promote potassium excretion through multiple interconnected tubular pathways. By inhibiting proximal glucose reabsorption, they induce a persistent osmotic diuresis that significantly increases distal tubular flow and sodium delivery. This high-flow state creates a potent, continuous stimulus for electrogenic potassium secretion. Concurrently, SGLT2 inhibitors suppress the sodium-hydrogen exchanger 3 (NHE3) in the proximal tubule, resulting in luminal alkalinization. This alkaline shift provides an additional defense mechanism by allosterically activating renal outer medullary potassium (ROMK) channels, further promoting renal potassium excretion.

Beyond direct tubular effects, systemic neurohormonal shifts also play a crucial role in maintaining potassium homeostasis [25]. The mild natriuresis and subsequent plasma volume reduction induced by SGLT2 inhibitors can activate the renin-angiotensin-aldosterone system. When this increased mineralocorticoid activity is coupled with enhanced distal sodium delivery, it strongly augments potassium secretion, particularly during the initial phase of therapy. Furthermore, the forced glycosuria alters systemic energy metabolism, leading to a reduction in insulin and an elevation in circulating glucagon levels. Glucagon acts directly on receptors along the distal nephron, exerting a rapid stimulatory effect on potassium secretion and completing a robust physiological defense against hyperkalemia.

Despite this theoretical propensity for potassium loss, SGLT2 inhibitors rarely induce hypokalemia due to the concurrent activation of sophisticated intrarenal compensatory mechanisms that restrict excessive excretion [25]. First, by increasing sodium delivery to the macula densa and decreasing sympathetic tone, SGLT2 inhibitors attenuate the overactivation of the renin-angiotensin-aldosterone system, thereby limiting aldosterone-driven potassium secretion. Second, the increased delivery of glucose to the distal nephron allosterically sensitizes the calcium-sensing receptor, which consequently upregulates the activity of the sodium-chloride cotransporter (NCC). Third, the enhanced distal delivery of α-ketoglutarate functions as an intrarenal paracrine signal that inhibits the epithelial sodium channel (ENaC) while promoting electroneutral sodium reabsorption. Ultimately, these coordinated tubular adaptations facilitate sodium reabsorption without provoking electrogenic potassium loss, effectively limiting the diuretic impact of the therapy while providing a robust physiological defense against the development of hypokalemia.

Ultimately, the dynamic interplay of these interconnected and compensatory mechanisms provides a compelling theoretical rationale for the generally favorable electrolyte safety profile of SGLT2 inhibitors. By balancing appropriate potassium excretion with safeguards against excessive loss, these agents help maintain potassium homeostasis. Consequently, this physiological balance substantially alleviates historical concerns regarding hyperkalemia, providing reassurance for their use even in vulnerable populations, such as patients with DKD. Nevertheless, while the absolute risk of severe dyskalemia is substantially attenuated, maintaining appropriate clinical vigilance and routine electrolyte monitoring remains a prudent standard of care in these high-risk cohorts.

Magnesium

Evidence from multiple randomized controlled trials demonstrates that SGLT2 inhibitors induce a modest yet significant increase in serum magnesium levels (approximately 0.08–0.2 mEq/L) [24], with canagliflozin exhibiting a distinct dose-dependent effect that is further amplified in patients with reduced renal function [26]. Notably, these agents have been shown to effectively normalize magnesium concentrations in patients with type 2 diabetes (T2D) who often present with hypomagnesemia [27]. From a clinical perspective, this mild elevation in serum magnesium—often accompanied by slight increases in serum potassium—is hypothesized to exert antiarrhythmic effects. Consequently, these favorable electrolyte shifts may partially underpin the remarkable cardiovascular benefits and reduced arrhythmia risks observed in landmark cardiovascular outcome trials, such as EMPA-REG OUTCOME [28] and CANVAS [12,29].

The elevation of serum magnesium concentrations induced by SGLT2 inhibitors is mediated by a complex interplay of several physiological mechanisms. Primarily, these agents mitigate the renal magnesium wasting characteristic of diabetes by improving insulin resistance, which subsequently restores the activity of transient receptor potential melastatin 6 (TRPM6) channels in the distal convoluted tubules [30]. This restorative effect is further supported by favorable hormonal shifts; Specifically, SGLT2 inhibitors elevate circulating glucagon levels, which directly enhances distal tubular magnesium reabsorption, and decrease insulin levels, which prevents the intracellular sequestration of magnesium and promotes its redistribution to the extracellular space [31,32,33]. Additionally, the mild extracellular volume depletion resulting from osmotic diuresis and natriuresis contributes to a relative increase in serum magnesium through hemoconcentration [24].

Interestingly, these magnesium-conserving mechanisms operate in opposition to inherent counter-regulatory forces. The same diuretic-induced hypovolemia that causes hemoconcentration also stimulates aldosterone secretion, which typically promotes renal magnesium excretion [34]. Nevertheless, the combined effects of TRPM6 restoration, favorable hormonal redistribution, and hemoconcentration robustly counterbalance the magnesiuric influence of aldosterone. Ultimately, this dynamic physiological interplay results in the net modest elevation of serum magnesium levels characteristically observed in clinical practice.

Phosphate

Regarding phosphate homeostasis, although SGLT2 inhibitors induce a mild elevation in serum phosphate—driven by a compensatory increase in proximal tubular Na⁺-3PO₄ ³⁻ cotransport following decreased sodium reabsorption [35]—this physiological shift does not universally increase bone fracture risk. Theoretically, this subtle hyperphosphatemia triggers a compensatory hormonal cascade involving elevated parathyroid hormone and fibroblast growth factor 23, which subsequently suppresses vitamin D synthesis and intestinal calcium absorption, hypothetically threatening bone mineral density. However, while initial data from the CANVAS trial linked canagliflozin to increased fractures [36,37], robust subsequent evidence from the EMPA-REG OUTCOME trial [29] and comprehensive meta-analyses [38,39] clarified that this is likely a drug-specific phenomenon rather than a class effect. Ultimately, clinical data demonstrate that these theoretical pathways of bone resorption do not translate into actual skeletal fragility for the majority of SGLT2 inhibitors.

GLP-1 RAs

Alongside their established cardiorenal benefits [40,41,42], GLP-1 RAs induce mild natriuresis similar to SGLT2 inhibitors [43]. By inhibiting proximal NHE3, they increase distal sodium delivery and elevate urinary pH, collectively promoting renal potassium excretion [44]. Consequently, clinical evidence shows a significantly lower incidence of hyperkalemia with GLP-1 RAs compared to dipeptidyl peptidase-4 inhibitors [45].

However, the renal physiology of GLP-1 RAs differs fundamentally from that of SGLT2 inhibitors. While GLP-1 RAs modulate tubular function via the gut-kidney axis, they do not drive profound osmotic diuresis or direct tubular electrolyte wasting. Instead, their renoprotection is predominantly mediated by pleiotropic effects, such as eGFR stabilization and albuminuria reduction. Thus, severe electrolyte derangements under GLP-1 RA therapy are typically secondary systemic phenomena rather than primary renal mechanisms. For instance, recent reports of severe hypokalemia (2.5–2.7 mmol/L) following semaglutide use were explicitly attributed to severe reductions in oral intake and gastrointestinal losses from severe nausea and vomiting [46]. Similarly, GLP-1 RA-induced hyponatremia is primarily driven by the syndrome of inappropriate antidiuretic hormone secretion—triggered by severe nausea and delayed gastric emptying—rather than mild diuresis [47]. Given their exceptionally low risk of hyperkalemia, GLP-1 RAs may be considered a favorable foundational therapy for susceptible populations, potentially facilitating safer concurrent treatment with RAS inhibitors or MRAs.

nsMRAs

nsMRAs represent a critical advancement in DKD pharmacotherapy, designed to overcome the limitations of traditional steroidal agents by providing potent anti-inflammatory and anti-fibrotic benefits. By utilizing a distinct, bulky non-steroidal structure, agents like finerenone achieve high receptor selectivity and offer a theoretically improved safety margin. Nevertheless, because they fundamentally antagonize aldosterone action, precise understanding and management of their impact on electrolyte derangements remain essential.

Hyperkalemia

MRAs effectively overcome the “aldosterone breakthrough” of standard RAS inhibition, offering additive anti-inflammatory and antifibrotic benefits [48]. However, the substantial hyperkalemia risk associated with traditional steroidal MRAs severely limits their clinical use—especially in patients with impaired eGFR—underscoring the critical need for safer alternatives. To address this, finerenone has been emerged as a promising nsMRA. Compared to traditional steroidal MRAs, finerenone exhibits greater mineralocorticoid receptor selectivity and binding affinity, affording higher therapeutic potency with a theoretically lower risk of hyperkalemia. The cardiorenal efficacy of finerenone in patients with T2D on a background of maximal RAS inhibition has been robustly demonstrated in 2 large RCTs. The FIDELIO-DKD study [49] demonstrated significant benefits in patients with advanced CKD (urine albumin-to-creatinine ratio [UACR] 30 to < 300 mg/g with eGFR 25 to < 60 mL/min/1.73 m², or UACR 300 to 5,000 mg/g with eGFR 25 to < 75 mL/min/1.73 m²) over a median follow-up of 2.6 years. Subsequently, the FIGARO-DKD [50] study expanded these findings to patients with T2D and less advanced CKD. Results showed a 29% risk reduction in heart failure hospitalizations and a 23% relative risk reduction in the kidney composite outcome (2.9% vs. 3.8%). While initial reports from these individual trials suggested that overall adverse events were comparable to placebo and severe hyperkalemia was uncommon, the FIDELITY pooled analysis [51] clarified that hyperkalemia events were indeed more frequent in the finerenone group than in the placebo group, particularly among patients with a low baseline eGFR.

Despite this increased risk relative to placebo, finerenone demonstrates a remarkably superior potassium safety profile when directly compared to traditional steroidal MRAs. In the phase 2 ARTS study [52], which evaluated finerenone (5–10 mg/day) versus spironolactone (25–50 mg/day) in patients with concurrent heart failure with reduced ejection fraction and CKD (eGFR 30–60 mL/min/1.73 m²), finerenone was associated with significantly smaller mean increases in serum potassium (0.04–0.30 vs. 0.45 mmol/L, p < 0.0001–0.0107) and a substantially lower incidence of hyperkalemia (5.3% vs. 12.7%, p = 0.048). This favorable safety profile was further corroborated by a comparative post hoc analysis [53] matching data from the FIDELITY program with the AMBER trial [54]. In populations with treatment-resistant hypertension and moderate-to-advanced CKD, the incidence of hyperkalemia was markedly lower in the finerenone cohort compared to the spironolactone cohort (12% vs. 64%). Furthermore, treatment discontinuation due to hyperkalemia was nearly negligible for finerenone compared to spironolactone (0.3% vs. 23%).

The improved potassium safety profile of finerenone relative to spironolactone is driven by distinct pharmacokinetic and pharmacodynamic mechanisms. First, unlike spironolactone, which accumulates in the kidneys and consequently drives excessive potassium retention, finerenone exhibits a balanced 1:1 tissue distribution between the heart and kidneys [55,56]. Second, finerenone has a short half-life of 2–3 hours and lacks active metabolites, preventing the unpredictable drug accumulation commonly seen with the long-acting active metabolites of spironolactone in patients with CKD [57]. Lastly, the bulky non-steroidal structure of finerenone induces a distinct conformational change in the mineralocorticoid receptor. This unique binding confers superior selectivity, potently inhibiting pro-inflammatory and pro-fibrotic pathways with minimal disruption to normal electrolyte handling [58].

nsMRA in combination with SGLT2 inhibitors

The implementation of a “four-pillar” therapeutic strategy in DKD has proven highly effective in reducing both CKD progression and all-cause mortality [59], establishing combination therapy as an indispensable standard of care. Ideally, such combination regimens should capitalize on complementary safety profiles to mutually offset specific adverse events.

The physiological rationale for combining SGLT2 inhibitors and nsMRAs lies in their complementary effects on distal potassium handling (Fig. 1). While nsMRAs carry an inherent risk of hyperkalemia by inhibiting potassium secretion mediated by the ROMK channel, SGLT2 inhibitors provide robust compensatory shunt. Crucially, the mineralocorticoid receptor-antagonistic effect of finerenone exerts a dominant transcriptional suppression on ROMK channels [60] that overrides any potential up-regulation induced by SGLT2 inhibitor-mediated luminal alkalinization [25]. Consequently, even though SGLT2 inhibitors significantly increase distal sodium delivery and urinary flow by blocking proximal reabsorption, ROMK activity remains pharmacologically suppressed under combination therapy. This high-flow state, however, serves as a potent mechanical stimulus that activates flow-sensitive Big Potassium (BK) channels in the distal nephron [61], thereby facilitating ‘flow-dependent potassium secretion’ to bypass the blocked ROMK pathway.

Fig. 1. Potential complementary effects of SGLT2i and nsMRA combination on distal potassium (K⁺) secretion via ROMK and BK channels.

(A) nsMRA monotherapy: nsMRAs, such as finerenone, potently block aldosterone action in the DCT & CD. This blockade potentially leads to the transcriptional and functional suppression of the ROMK channel. Because the downstream luminal delivery of Na⁺ and urinary flow rate remain low under monotherapy, the flow-sensitive BK channel cannot be mechanically activated. Consequently, overall distal K⁺ secretion is blocked, shifting the clinical balance toward an increased risk of hyperkalemia. (B) SGLT2 inhibitor monotherapy: SGLT2 inhibitors block proximal tubular reabsorption, resulting in a high-flow state and increased delivery of Na⁺ and fluid to the distal nephron. This process also induces luminal alkalinization. The luminal alkalinization provides a chemical stimulus that upregulates ROMK channel activity. Simultaneously, the pronounced increase in delivered flow acts as a potent mechanical stimulus that activates the flow-sensitive, high-conductance BK channels. This dual activation may accelerate distal K⁺ wasting, driving a clinical trend toward hypokalemia. (C) Combination therapy (SGLT2 inhibitor + nsMRA): When an SGLT2 inhibitor is co-administered with an nsMRA, their distinct physiological pathways intersect. Crucially, the MR-antagonistic effect of finerenone potentially exerts a dominant transcriptional suppression on ROMK channels that may override the potential upregulation induced by SGLT2 inhibitor-mediated luminal alkalinization; thus, the ROMK pathway remains pharmacologically blocked. However, the persistent high distal Na⁺ delivery and delivered flow generated by the SGLT2 inhibitor serve as a robust, continuous mechanical stimulus that can activate the flow-dependent BK channels. This proposed compensatory BK-mediated shunt appears to bypass the blocked ROMK pathway, facilitating sufficient K⁺ secretion and effectively mitigating the baseline hyperkalemia risk associated with nsMRA monotherapy.

BK, big potassium channel; CD, collecting duct; DCT, distal convoluted tubule; K⁺, potassium; MR, mineralocorticoid receptor; Na⁺, sodium; nsMRA, non-steroidal mineralocorticoid receptor antagonist; ROMK, renal outer medullary potassium; SGLT2i, sodium-glucose cotransporter-2 inhibitor.

In line with these biological mechanisms, early post-hoc analyses from the FIDELITY program generated optimism, demonstrating that baseline SGLT2 inhibitor use significantly lowered the incidence of finerenone-induced hyperkalemia. This premise was prospectively evaluated in the CONFIDENCE trial, which confirmed that combining empagliflozin and finerenone achieves a profound, synergistic reduction in albuminuria compared to either monotherapy. While initial reports sparked hopes of superior potassium safety, a recent 180-day secondary analysis of the CONFIDENCE trial [62] provided a more complex clinical picture. Although the incidence of hyperkalemia remained numerically lower in the combination arm (15.1%) than in the finerenone monotherapy arm (18.8%), this reduction did not reach statistical significance. Ultimately, while SGLT2 inhibitors do not completely neutralize the hyperkalemia risk associated with nsMRAs, severe events necessitating treatment discontinuation are exceedingly rare. Given the overwhelming antiproteinuric benefits, the concurrent use of SGLT2 inhibitors and nsMRAs remains a highly recommended therapeutic strategy, provided it is accompanied by routine potassium monitoring.

Hyponatremia

Finerenone is associated with a marginally higher incidence of hyponatremia compared to placebo across eGFR subgroups (approx. 1.1–1.2% vs. 0.5–0.8%), although it rarely necessitates treatment discontinuation [63]. Although finerenone possesses a distinct non-steroidal structure, its fundamental mineralocorticoid antagonism can still contribute to the development of hyponatremia through two primary renal mechanisms. First, by blocking aldosterone action in the distal tubule and collecting duct, finerenone inhibits the synthesis of ENaC [64]. This disruption of Na⁺/K⁺ exchange promotes direct renal sodium wasting. Second, it impairs the kidney’s urinary diluting capacity, which can precipitate dilutional hyponatremia even in the absence of pronounced hypovolemia [65]. Notably, these dose-dependent effects are clinically more evident in patients with mild-to-moderate, rather than severe, CKD [66].

CLINICAL CONSIDERATIONS FOR ELECTROLYTE MONITORING

Ultimately, translating the clinical benefits of these state-of-the-art therapeutic classes into safe clinical practice requires structured and individualized electrolyte monitoring. To optimize patient safety, post-prescription electrolyte monitoring intervals must be clearly defined and individualized based on the patient’s baseline renal function. For standard-risk patients initiating either nsMRA monotherapy or combination therapy, the first electrolyte follow-up should be scheduled within a specific 2- to 4-week window following initiation or dose escalation. Crucially, for high-risk individuals—particularly those with advanced CKD and a baseline eGFR below 30 mL/min/1.73 m²—this monitoring interval for serum potassium and renal function must be significantly shortened to 1 to 2 weeks following the initiation or dose escalation of either nsMRAs or combination therapy. This closer clinical oversight provides a critical safety window to proactively detect and manage potential electrolyte derangements as patients approach end-stage renal disease.

Beyond these routine clinical checks, implementing “sick day rules” during acute, dehydrating illnesses (such as severe vomiting or diarrhea) is widely recommended to protect patients during intercurrent events [67]. In these acute scenarios, the temporary suspension of SGLT2 inhibitors, RAS inhibitors, or nsMRAs should be considered a prudent and effective approach to proactively prevent acute kidney injury.

CONCLUSION

The pharmacological management of DKD has been revolutionized by the “four-pillar” approach, shifting the paradigm beyond traditional RAS inhibition. While these novel therapeutic classes offer robust cardiorenal protection, understanding their distinct impacts on electrolyte homeostasis is essential for safe clinical practice. SGLT2 inhibitors present a highly favorable electrolyte profile; their unique mechanisms of osmotic diuresis and tubular transport modulation are notably associated with a reduced risk of hyperkalemia. Similarly, GLP-1 receptor agonists carry an exceptionally low intrinsic risk of direct renal electrolyte wasting, with rare derangements such as hypokalemia occurring primarily as secondary systemic consequences of severe gastrointestinal intolerance.

Despite these reassuring safety profiles, the integration of nsMRAs introduces a mild risk of hyperkalemia and dilutional hyponatremia. However, their distinct pharmacokinetic properties and unique receptor selectivity significantly diminish these risks compared to traditional steroidal MRAs. Crucially, harnessing the complementary physiological mechanisms of these pillars—particularly the concurrent administration of SGLT2 inhibitors and nsMRAs—creates a highly synergistic strategy that attenuates this hyperkalemic adverse effect while maximizing antiproteinuric benefits.