Impact of CRRT on Serum Carnitine and Micronutrient Levels

March 12, 2026 updated by: Mete Erdemir, Gulhane Training and Research Hospital

The Carnitine Dichotomy in CRRT: Dialytic Depletion of Short-Chain Fractions Versus Retention of Long-Chain Mitochondrial Biomarkers.

This study aims to investigate the changes in blood levels of micronutrients and carnitine in critically ill patients with Acute Kidney Injury (AKI) who are undergoing Continuous Renal Replacement Therapy (CRRT). While CRRT is a life-saving intervention for managing metabolic disturbances and fluid overload in patients with Stage 2-3 AKI, it may also lead to the inadvertent removal of essential micronutrients (vitamins, trace elements, and amino acids) through the extracorporeal circuit.

The research will prospectively compare 100 adult patients across two groups: those receiving CRRT and those managed without CRRT. Researchers will analyze blood samples and effluent fluid to determine the clearance rates and total losses of various substances, including carnitine, selenium, zinc, and various amino acids. By comparing levels at the first hour and 24th hour of intensive care admission, the study seeks to determine if CRRT significantly contributes to micronutrient deficiencies in this vulnerable population.

Study Overview

Status

Completed

Conditions

Intervention / Treatment

Detailed Description

Background and Rationale:

Acute Kidney Injury (AKI) is characterized by a sudden loss of glomerular filtration rate and is a major factor increasing mortality and morbidity in hospitalized patients. In critically ill patients, Continuous Renal Replacement Therapy (CRRT) is frequently used to manage metabolic disturbances and fluid overload due to its advantages in hemodynamic stability. However, exposure to the extracorporeal circuit may lead to significant losses of micronutrients, including trace elements (e.g., selenium, zinc, copper) and water-soluble vitamins, which play crucial roles in cellular function and metabolism.

Study Objective:

The primary objective of this prospective study is to investigate the changes in serum and effluent (waste fluid) micronutrient levels in patients undergoing CRRT and to compare these levels with patients who have Stage 2-3 AKI but do not require CRRT.

Methodology and Procedures:

Study Setting and Design This prospective study was conducted in a 36-bed general Intensive Care Unit (ICU) at a tertiary education and research hospital. Patients diagnosed with Acute Kidney Injury (AKI) Stage 2 or 3 according to the KDIGO guidelines were included. Within the first hour of ICU admission, patients were evaluated for Continuous Renal Replacement Therapy (CRRT) requirement and divided into two groups: those receiving CRRT and those not receiving CRRT. The decision to initiate CRRT was made by the attending clinician independent of the study team.

Eligibility Criteria Inclusion criteria were:

Patients aged 18-90 years,Diagnosis of AKI Stage 2 or 3 according to KDIGO,Evaluation for CRRT requirement within the first hour of ICU admission.

Exclusion criteria included:End-stage renal disease or history of chronic RRT., AKI due to dialyzable toxins,Child-Pugh C liver cirrhosis,Terminal malignancy,AKI secondary to cardiac arrest,High risk of mortality within the first 24 hours,Prior RRT for the current AKI episode,History of kidney transplantation,Prior inclusion in this study,Pregnancy or breastfeeding,Lack of informed consent from the patient or legal representative.

Clinical Data and Sample Collection Demographic data (age, sex), APACHE-II and SOFA scores, BMI, and admission diagnoses were recorded. Routine laboratory parameters including serum albumin, total protein, creatinine, urea, electrolytes, CRP, and blood gas values (pH, bicarbonate, lactate) were measured at the 1st and 24th hours.For micronutrient analysis, blood samples were collected at the 1st hour of ICU admission for all patients. Subsequent sampling was performed at the 24th hour of CRRT for the treatment group and at the 24th hour of ICU stay for the non-CRRT group. Samples were centrifuged at 4000 rpm for 5 minutes and stored at -80°C. Analyzed parameters included:Trace elements: Selenium, zinc, copper, iron.Vitamins: Vitamin B12, Vitamin C, folate.Amino acids: 22 subforms including leucine, isoleucine, valine, and others.Carnitine: Various subforms.CRRT Procedure and Effluent Analysis All CRRT procedures were performed in Continuous Veno-venous Hemodialysis (CVVHD) mode at a dose of 30 mL/kg/hour. An Ultraflux AV1000S polysulfone filter (1.8 m2) was used. Anticoagulation was achieved with unfractionated heparin, and no ultrafiltration was applied during the study period. Dialysate flow rate (Qd) was maintained at 30% of the blood flow rate (Qb) to ensure ideal dialysate saturation, with Qb fixed between 100-140 mL/min.To calculate extracorporeal losses, 20 mL samples were collected from each effluent bag during the 24-hour CRRT period and stored at -80°C. Total loss was calculated by multiplying the concentration in each bag by its total volume. Due to instability under light and room temperature, vitamins (C and B12) were excluded from effluent analysis to avoid confounding results.

Study Type

Observational

Enrollment (Actual)

43

Contacts and Locations

This section provides the contact details for those conducting the study, and information on where this study is being conducted.

Study Locations

  • Turkey (Türkiye)
    • keçiören
      • Ankara, keçiören, Turkey (Türkiye), 06010
        • Gulhane Training and Research Hospital, Intensive Care Clinic

Participation Criteria

Researchers look for people who fit a certain description, called eligibility criteria. Some examples of these criteria are a person's general health condition or prior treatments.

Eligibility Criteria

Ages Eligible for Study

  • Adult
  • Older Adult

Accepts Healthy Volunteers

No

Sampling Method

Non-Probability Sample

Study Population

The study population consists of adult patients (aged 18-90 years) admitted to a 36-bed general Intensive Care Unit (ICU) in a tertiary education and research hospital. The population focuses on patients diagnosed with Acute Kidney Injury (AKI) Stage 2 or 3 according to the KDIGO clinical practice guidelines. Participants are selected from patients who require an evaluation for Continuous Renal Replacement Therapy (CRRT) within the first hour of their ICU admission. The cohort includes a diverse range of critically ill patients, excluding those with end-stage chronic conditions or specific comorbidities that could confound the analysis of micronutrient clearance

Description

Inclusion Criteria:

  • Patients aged 18-90 years
  • Diagnosis of AKI Stage 2 or 3 according to KDIGO
  • Evaluation for CRRT requirement within the first hour of ICU admission.

Exclusion Criteria:

  • End-stage renal disease or history of chronic RRT
  • AKI due to dialyzable toxins,Child-Pugh C liver cirrhosis
  • Terminal malignancy,AKI secondary to cardiac arrest
  • High risk of mortality within the first 24 hours
  • Prior RRT for the current AKI episode,History of kidney transplantation
  • Prior inclusion in this study
  • Pregnancy or breastfeeding
  • Lack of informed consent from the patient or legal representative.

Study Plan

This section provides details of the study plan, including how the study is designed and what the study is measuring.

How is the study designed?

Design Details

What is the study measuring?

Primary Outcome Measures

Outcome Measure
Measure Description
Time Frame
Extracorporeal Clearance of Micronutrients and Carnitine
Time Frame: At the 24th hour of Continuous Renal Replacement Therapy (CRRT)
Calculation of the clearance rates for trace elements (selenium, zinc, copper, iron), carnitine subforms, and 22 different amino acids by analyzing their concentrations in the blood and effluent (waste fluid) during the 24-hour Continuous Renal Replacement Therapy (CRRT) period.
At the 24th hour of Continuous Renal Replacement Therapy (CRRT)

Secondary Outcome Measures

Outcome Measure
Measure Description
Time Frame
The difference in micronutrient status between patients receiving and not receiving CRRT.
Time Frame: 24 hours after hospital admission/start of treatment.
Comparison of serum micronutrient, vitamin, and amino acid concentrations between the group receiving Continuous Renal Replacement Therapy (CRRT) at a dose of 30 mL/kg/hour and the control group (non-CRRT ICU patients). This aims to isolate the effect of the CRRT filter on nutritional loss compared to standard ICU metabolic changes.
24 hours after hospital admission/start of treatment.
Clinical Correlation
Time Frame: Through study completion (up to 24 hours)
Assessment of the relationship between micronutrient losses and clinical severity scores (APACHE-II, SOFA) and inflammatory markers (CRP).
Through study completion (up to 24 hours)
Changes in Serum Carnitine Concentrations
Time Frame: Baseline (1st hour of admission) and 24 hours
Comparison of serum levels of carnitine between the 1st hour of ICU admission and the 24th hour.
Baseline (1st hour of admission) and 24 hours
comparison of serum amino acid concentration
Time Frame: first hour of intensive care unite admission and the 24th hour
comparison of serum amino acid concentration between first hour of intensive care unite admission and the 24th hour
first hour of intensive care unite admission and the 24th hour
comparison of serum vitamins(B12,folat) concentrations
Time Frame: first hour of intensive care admission and the 24 th hour
comparison of serum vitamins(B12,folat) concentration between first hour of intensive care admission and the 24 th hour
first hour of intensive care admission and the 24 th hour

Collaborators and Investigators

This is where you will find people and organizations involved with this study.

Sponsor

Gulhane Training and Research Hospital

Publications and helpful links

The person responsible for entering information about the study voluntarily provides these publications. These may be about anything related to the study.

General Publications

Study record dates

These dates track the progress of study record and summary results submissions to ClinicalTrials.gov. Study records and reported results are reviewed by the National Library of Medicine (NLM) to make sure they meet specific quality control standards before being posted on the public website.

Study Major Dates

Study Start (Actual)

January 1, 2023

Primary Completion (Actual)

March 15, 2025

Study Completion (Actual)

December 15, 2025

Study Registration Dates

First Submitted

February 20, 2026

First Submitted That Met QC Criteria

March 8, 2026

First Posted (Actual)

March 12, 2026

Study Record Updates

Last Update Posted (Actual)

March 16, 2026

Last Update Submitted That Met QC Criteria

March 12, 2026

Last Verified

February 1, 2023

More Information

Terms related to this study

Keywords

Additional Relevant MeSH Terms

Other Study ID Numbers

  • 2022/24

Plan for Individual participant data (IPD)

Plan to Share Individual Participant Data (IPD)?

UNDECIDED

This information was retrieved directly from the website clinicaltrials.gov without any changes. If you have any requests to change, remove or update your study details, please contact register@clinicaltrials.gov. As soon as a change is implemented on clinicaltrials.gov, this will be updated automatically on our website as well.

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