Salt substitute to protect kidney function after kidney tumor surgery

Kidney-protective Intervention With Salt Substitute After Kidney Tumor Surgery: a Single-center Randomized Controlled Study(KISS Study)

This randomized study will test whether using a potassium-enriched salt substitute instead of regular salt helps protect kidney function in adults after kidney tumor surgery.

Quick facts

• Phase: NA
• Study type: Interventional
• Enrollment: 200 (estimated)
• Ages: 18 Years and up
• Sex: All
• Sponsor: Jinling Hospital, China (other)
• Drugs / interventions: immunotherapy
• Locations: 1 site (Nanjing, Jiangsu)
• Trial ID: NCT07062952 on ClinicalTrials.gov

What this trial studies

This open-label randomized controlled trial at Jinling Hospital will assign adults who have undergone radical or partial nephrectomy to either a potassium-enriched low-sodium salt substitute diet or a regular salt diet and follow them over time. The primary outcome is change in estimated glomerular filtration rate (eGFR); secondary outcomes include safety (particularly serum potassium), adherence, and feasibility of the dietary intervention. Eligible participants must have preoperative eGFR >60 ml/min/1.73m², normal contralateral renal function, serum potassium <4.8 mmol/L, and predominantly home-prepared meals. Investigators will monitor labs and adverse events and compare renal function trajectories between groups to see if the salt substitute slows postoperative kidney function decline.

Who should consider this trial

Good fit: Adults (≥18) who had radical or partial nephrectomy, had preoperative eGFR >60 ml/min/1.73m², normal contralateral kidney function, serum potassium <4.8 mmol/L, predominantly eat home-prepared meals, and can provide informed consent are ideal candidates.

Not a fit: Patients with reduced baseline kidney function, impaired contralateral kidney, current use of potassium-sparing diuretics or potassium supplements, or other risks for hyperkalemia are unlikely to benefit or may be excluded for safety reasons.

Why it matters

Potential benefit: If successful, switching to a low-sodium, potassium-enriched salt could slow postoperative loss of kidney function and lower long-term CKD risk with a simple dietary change.

How similar studies have performed: Large population trials of salt substitutes have shown reductions in blood pressure and cardiovascular events, but direct evidence that salt substitutes protect kidney function after nephrectomy is limited.

Eligibility criteria

Inclusion Criteria:

* Participants must meet all of the following criteria:

  1. Voluntary participation with signed informed consent from both the primary participant and all cohabiting family members, with commitment to study procedures and follow-up;
  2. Age ≥18 years at enrollment (when signing informed consent), any gender;
  3. Diagnosed kidney tumor patients who underwent radical nephrectomy or partial nephrectomy (no restrictions on surgical approach);
  4. Preoperative eGFR \>60 ml/min/1.73m² (calculated by CKD-EPI equation);
  5. Serum potassium \<4.8 mmol/L;
  6. Predominantly home-based dietary habits (\>90% meals prepared at home, assessed via self-report);
  7. Normal contralateral renal function at screening;
  8. Normal cardiopulmonary and hepatic function:

Exclusion Criteria:

* Participants will be excluded if they meet any of the following:

  1. Participant or cohabiting family members currently using potassium-sparing diuretics or potassium supplements, or prior use of salt substitutes;
  2. Post-discharge eGFR \<45 ml/min/1.73m² without significant fluctuation;
  3. Comorbid chronic kidney diseases (e.g., diabetic nephropathy, lupus nephritis);
  4. Preoperative history of urinary tract obstruction;
  5. Cohabiting family member(s) with CKD (eGFR \<45 ml/min/1.73m²);
  6. Planned postoperative nephrotoxic medications (e.g., anti-neoplastic agents, immunotherapy);
  7. Uncontrolled diabetes (HbA1c ≥12%);
  8. Uncontrolled hypertension (seated SBP ≥180 mmHg or DBP ≥110 mmHg), symptomatic hypotension (SBP \<90 mmHg), or clinically evident hypovolemia;
  9. Preoperative proteinuria (≥1+ on dipstick);
  10. Severe cardiovascular disease (NYHA Class III-IV), gastrointestinal obstruction, or hyperkalemia history;
  11. BMI \<18.5 kg/m² or \>30 kg/m²;
  12. Participation in another clinical trial ≤30 days before randomization or concurrently;
  13. Communication barriers or anticipated non-adherence;
  14. Structural/functional urological abnormalities (e.g., duplicated kidneys, polycystic kidneys, renal artery stenosis, stones, BPH) or indwelling catheters;
  15. Prior radiotherapy/ablation/surgery on the contralateral kidney;
  16. Life expectancy \<6 months (e.g., metastatic renal carcinoma).

Where this trial is running

Nanjing, Jiangsu

• Jinling Hospital, Affiliated Hospital of Medical School, Nanjing University, Nanjing — Nanjing, Jiangsu, China (RECRUITING)

Study contacts

• Study coordinator: Qu Le M.D

Conditions: Kidney Tumors, CKD, Salt Substitute, Nephrectomy, eGFR, kidney tumor, Salt substitute, nephrectomy