Pilot Trial of Oral Sodium Bicarbonate Versus Higher Dialysate Bicarbonate in Hemodialysis Patients With Metabolic Acidosis

NCT07688434 | Not Yet Recruiting

• 1 other identifier: BICARDIS-2026-01
• Study Type: interventional
• Target: 37
• Locations: 1 country
• Sites: 1

Brief Summary

Metabolic acidosis is frequent in chronic hemodialysis patients and is associated with adverse clinical outcomes. Two commonly used strategies to correct acidosis are oral sodium bicarbonate supplementation and increasing the bicarbonate concentration of the dialysate, but their comparative effectiveness and tolerance in routine care remain uncertain. This pilot, prospective, randomized, open-label, single-center trial will compare oral sodium bicarbonate versus higher dialysate bicarbonate in chronic hemodialysis patients with metabolic acidosis, using predialysis plasma bicarbonate concentrations, so-called "reserves alcalines" or "alkaline reserves" in local laboratory reports, as a pragmatic marker of acid-base status. Approximately 30 acidotic patients (serum bicarbonate \< 22 mmol/L) will be randomized 1:1 to receive either oral sodium bicarbonate or an increase in dialysate bicarbonate for 6 weeks. An additional non-acidotic observational group will provide descriptive reference data. The primary outcome is the change in predialysis serum bicarbonate from baseline (Day 0) to Day 42 between the two randomized arms. Secondary outcomes include the proportion of patients reaching target serum bicarbonate levels, the weekly kinetics of correction, dialysis adequacy (Kt/V and online clearance monitoring), intradialytic tolerance (blood pressure, cramps, hypotension, symptoms), sodium-related safety (natremia, interdialytic weight gain), and the effects of acidosis correction on nutritional and bone-mineral metabolism, including changes in serum albumin, calcium, phosphorus, and parathyroid hormone (PTH). Feasibility indicators such as recruitment, retention, adherence to treatment and dialysate adjustment, and data completeness will also be described to inform the design of a larger definitive trial.

Conditions

End-stage Renal Disease (ESRD); Metabolic Acidosis; Chronic Hemodialysis

Keywords

Hemodialysis; End-Stage Renal Disease; Metabolic Acidosis; Oral sodium Bicarbonate; Dialysate Bicarbonate; Pilot Trial; Bicarbonate Supplementation

Outcome Measures

Primary Outcomes (1)

• Change in Predialysis Serum Bicarbonate ("Reserves Alcalines") Between Day 0 and Day 42

  Predialysis serum (or plasma) bicarbonate concentrations, so-called "reserves alcalines" or "alkaline reserves" in local laboratory reports, will be measured at baseline (Day 0) and after 6 weeks (Day 42) in chronic hemodialysis patients with metabolic acidosis. The primary outcome is the change in predialysis serum bicarbonate between Day 0 and Day 42 (Δ serum bicarbonate), comparing the oral sodium bicarbonate arm and the higher dialysate bicarbonate arm. Serum bicarbonate will be expressed in mmol/L, and metabolic acidosis at inclusion is defined as predialysis serum bicarbonate \< 22 mmol/L.

  From baseline (Day 0) to Day 42

Secondary Outcomes (11)

• Proportion of Patients Achieving Target Serum Bicarbonate at Day 42

  Day 42

• Weekly Kinetics of Predialysis Serum Bicarbonate

  Day 0, Day 7, Day 14, Day 21, Day 28, Day 35, Day 42.

• Intradialytic hypotension episodes

  From baseline (Day 0) to Day 42

• Dialysis Adequacy

  From baseline (Day 0) to Day 42

• Predialysis Serum Sodium

  From baseline (Day 0) to Day 42

Other Outcomes (1)

• Feasibility of the Pilot Trial

  From study start (screening and inclusion) to Day 42

Study Arms (3)

Oral Sodium Bicarbonate Arm

EXPERIMENTAL

Adult chronic hemodialysis patients with metabolic acidosis (serum/plasma bicarbonate \< 22 mmol/L) randomized to receive oral sodium bicarbonate supplementation according to a stepwise dosing algorithm based on weekly predialysis serum bicarbonate ("reserves alcalines").

Dietary Supplement: Oral sodium bicarbonate

Increased Dialysate Bicarbonate Arm

ACTIVE COMPARATOR

Adult chronic hemodialysis patients with metabolic acidosis (serum/plasma bicarbonate \< 22 mmol/L) randomized to receive an increased dialysate bicarbonate concentration according to a predefined stepwise algorithm based on weekly predialysis serum bicarbonate ("reserves alcalines" or "alkaline reserves" in local laboratory reports).

Other: Increased Dialysate Bicarbonate

Non-Acidotic Hemodialysis Control Group

NO INTERVENTION

Adult chronic hemodialysis patients with stable, adequate predialysis serum (or plasma) bicarbonate concentrations (so-called "reserves alcalines" or "alkaline reserves" in local laboratory reports), who are not acidotic according to the study definition, will be included as a non-randomized observational control group. These patients will continue their usual dialysis prescription and routine care without any specific study-mandated change in oral bicarbonate or dialysate bicarbonate. They will be followed over the same 6-week period with collection of serum bicarbonate, sodium, potassium, dialysis adequacy (Kt/V and online clearance monitoring), blood pressure, interdialytic weight gain, and intradialytic symptoms, to provide descriptive reference data on acid-base status, dialysis adequacy, and tolerance in non-acidotic hemodialysis patients

Interventions

Oral sodium bicarbonate DIETARY_SUPPLEMENT

Oral sodium bicarbonate given as Bicardis 500 mg capsules, used as a dietary supplement in Tunisia, administered according to a standardized algorithm based on predialysis serum bicarbonate concentrations, so-called "reserves alcalines" in local laboratory reports. At baseline, an initial dose is prescribed according to the severity of metabolic acidosis: 1 capsule/day if 20-21.9, 2 capsules/day if 18-19.9, 3 capsules/day if 16-17.9, 4 capsules/day if \<16 mmol/L. At each weekly visit, the same dose is maintained if reserves alcalines remain below the target range and the weekly increase is ≤ 3 mmol/L; the dose is reduced to the previous lower level if the weekly increase is \> 3 mmol/L or if predialysis bicarbonate enters the predefined target range (22-24 mmol/L); oral bicarbonate is reduced or stopped if predialysis bicarbonate exceeds the upper limit of the target range (\> 24 mmol/L) to avoid alkalosis, and the dose is increased if reserves alcalines do not improve or decrease.

Also known as: Bicardis

Oral Sodium Bicarbonate Arm

Increased Dialysate Bicarbonate OTHER

Adjustment of the dialysate bicarbonate concentration will be performed according to a standardized titration strategy based on predialysis serum bicarbonate concentrations ("reserves alcalines" in local laboratory reports). At baseline, an initial increase in dialysate bicarbonate is prescribed according to the severity of metabolic acidosis: +1 mmol/L if serum bicarbonate is 20-21.9 mmol/L, +2 mmol/L if 18-19.9 mmol/L, +3 mmol/L if 16-17.9 mmol/L, and a larger or individualized increase if \< 16 mmol/L. At each weekly visit, dialysate bicarbonate is then adjusted as follows: it is maintained if reserves alcalines remain below the target range and the weekly increase is ≤ 3 mmol/L; it is reduced to the previous lower level if the weekly increase is \> 3 mmol/L or if predialysis bicarbonate enters the predefined target range (22-24 mmol/L); and it is reduced or returned to the standard level if predialysis bicarbonate exceeds the upper limit of the target range (\> 24 mmol/L).

Increased Dialysate Bicarbonate Arm

Eligibility Criteria

• Age: 18 Years+
• Sex: all
• Healthy Volunteers: No
• Age Groups: Adult (18-64), Older Adult (65+)

You may qualify if:

• Age ≥ 18 years.
• Chronic hemodialysis for at least 3 months.
• Stable hemodialysis prescription: 3 times a week, high-flux dialyzers, no major change in dialysis prescription in the previous weeks.
• Predialysis low "alkaline reserves" (serum bicarbonate concentration) according to the operational threshold used in the unit (e.g., "alkaline reserves" \< 22 mmol/L), consistent with KDIGO 2017 definition of metabolic acidosis.
• Ability to give written informed consent.
• For the observational group:
• Age ≥ 18 years.
• Chronic hemodialysis for at least 3 months.
• Hemodialysis 3 times a week, high-flux dialyzers.
• Predialysis "alkaline reserves" considered stable and within the locally defined normal range (≥ 22mmol/L).
• Ability to give written informed consent.

You may not qualify if:

• Recent hemodynamic instability (e.g., repeated intradialytic hypotension or unstable blood pressure in the previous weeks).
• Recent hospitalization for an acute condition.
• Acute infection or major intercurrent acute event at the time of screening.
• Severe digestive disorders limiting oral intake (e.g., persistent vomiting, severe malabsorption, or any condition preventing safe oral Bicardis administration).
• Known hypernatremia or high risk of uncontrolled sodium and fluid overload (as judged by the investigator).
• Severe uncontrolled hypercalcemia or hypocalcemia.
• Any condition that, in the investigator's judgment, would preclude safe participation or interfere with study procedures (e.g., very limited life expectancy, inability to attend scheduled visits).
• Refusal to participate or inability to provide written informed consent.

Sponsors & Collaborators

• University of Sfax: lead

Study Sites (1)

Social security fund polyclinic

Sfax, 3080, Tunisia

Location

MeSH Terms

Conditions

Kidney Failure, Chronic; Acidosis

Interventions

Sodium Bicarbonate

Condition Hierarchy (Ancestors)

Renal Insufficiency, Chronic; Renal Insufficiency; Kidney Diseases; Urologic Diseases; Female Urogenital Diseases; Female Urogenital Diseases and Pregnancy Complications; Urogenital Diseases; Male Urogenital Diseases; Chronic Disease; Disease Attributes; Pathologic Processes; Pathological Conditions, Signs and Symptoms; Acid-Base Imbalance; Metabolic Diseases; Nutritional and Metabolic Diseases

Intervention Hierarchy (Ancestors)

Bicarbonates; Carbonates; Carbonic Acid; Carbon Compounds, Inorganic; Inorganic Chemicals; Sodium Compounds

Study Officials

• Lobna Ben Mahmoud, MD, PhD, Professor

  University of Sfax, Faculty of medecine of Sfax

  STUDY DIRECTOR

• Ahmed Hakim, MD, Professor

  University of Sfax, Faculty of medecine of Sfax

  STUDY CHAIR

Central Study Contacts

Azza KHEDHIRI, MD

CONTACT

+21623146019; ik4m23@gmail.com

Lobna Ben Mahmoud, MD, PhD, Professor

CONTACT

+21696365092; benmahmoud_lobna@medecinesfax.org

Study Design

• Study Type: interventional
• Phase: not applicable
• Allocation: RANDOMIZED
• Masking: NONE
• Purpose: TREATMENT
• Intervention Model: PARALLEL
• Sponsor Type: OTHER
• Responsible Party: PRINCIPAL INVESTIGATOR
• PI Title: Principal investigator, Head of the Hemodialysis Department of the Sfax Social Security fund polyclinic

Model Details: This is a pilot, prospective, randomized, open-label, single-center trial with three parallel groups. Two active arms include chronic hemodialysis patients with metabolic acidosis (serum/plasma bicarbonate \< 22 mmol/L) randomized 1:1 to oral sodium bicarbonate supplementation or increased dialysate bicarbonate concentration. Randomization among acidotic patients is performed in matched pairs according to baseline serum bicarbonate (so-called "reserves alcalines" in local laboratory reports) and age, using a computer-generated random number within each pair (block size 2) to ensure balanced acidosis severity between arms. A third non-acidotic group with stable serum bicarbonate levels is followed as an observational control and does not undergo randomization.

Study Record Dates

• First Submitted: June 21, 2026
• First Posted: July 7, 2026
• Study Start: July 1, 2026
• Primary Completion (Estimated): September 1, 2026
• Study Completion (Estimated): September 1, 2026
• Last Updated: July 21, 2026

Record last verified: 2026-07

Locations

TU (1)