Kidney Transplant; Complications, Metabolic Acidosis, Vascular Diseases
Conditions
Brief summary
Lower serum bicarbonate levels, even within the normal laboratory range, in kidney transplant recipients (KTRs) are associated with an increased risk of graft loss, cardiovascular events and mortality. Because acid retention is common in KTRs, it is plausible that alkali therapy in KTRs may also result in improved vascular and graft function. The investigators will perform a randomized, double-blinded, placebo-controlled, 12 month study in 120 KTRs to examine the effect of sodium bicarbonate therapy on surrogate markers of CVD and graft function. The overall hypothesis is that treatment with bicarbonate will improve indicators of vascular and graft function in KTRs by decreasing complement activation.
Interventions
DRUGSodium bicarbonate
Oral sodium bicarbonate at 0.5 mEq/kg-lean body weight/day
DRUGPlacebo
Placebo at 0.5 mEq/kg-lean body weight/day
Sponsors
National Institute of Diabetes and Digestive and Kidney Diseases (NIDDK)
University of Colorado, Denver
Study design
Allocation
RANDOMIZED
Intervention model
PARALLEL
Primary purpose
TREATMENT
Masking
QUADRUPLE (Subject, Caregiver, Investigator, Outcomes Assessor)
Eligibility
Sex/Gender
ALL
Age
18 Years to 80 Years
Healthy volunteers
No
Inclusion criteria
* Age 18-80 years * Serum bicarbonate 16-24 mEq/L on 2 separate measurements (at least 1 day apart) * Kidney transplant received 1 year prior to randomization * eGFR ≥ 45 ml/min/1.73m2 by CKD-EPI equation * Blood pressure \<130/80 mm Hg prior to randomization * BMI \< 40 kg/m2 (FMD measurements can be inaccurate in severely obese patients). * Able to provide consent * Immunosuppression regimen consisting of tacrolimus, mycophenolate mofetil and prednisone (95% of patients at University of Colorado are on this regimen) * Stable immunosuppression regimen for at least three months prior to randomization * Stable anti-hypertensive regimen for at least one month prior to randomization * Not taking medications that interact with agents administered during experimental sessions (e.g. sildenafil interacts with nitroglycerin).
Exclusion criteria
* Significant comorbid conditions that lead the investigator to conclude that life expectancy is less than 1 year * Use of chronic daily oral alkali within the last 3 months (including sodium bicarbonate, calcium carbonate or baking soda) * Uncontrolled hypertension * Serum potassium \< 3.3 or ≥ 5.5 mEq/L at screening * New York Heart Association Class 3 or 4 heart failure symptoms, known EF ≤30%, or hospital admission for heart failure within the past 3 months * Nephrotic range proteinuria (urine complement activation fragment measurements may not be accurate with severe proteinuria) * Factors judged to limit adherence to interventions * Current participation in another research study * Pregnancy or planning to become pregnant or currently breastfeeding * Chronic use of supplemental oxygen * Use of anticoagulants
Design outcomes
Primary
| Measure | Time frame | Description |
|---|---|---|
| Change in Brachial artery flow mediated dilation at 12 months | Baseline and 12 months | Brachial artery FMD will be determined using high-resolution ultrasonographyECG-gated end-diastolic ultrasound images and Doppler flow of the brachial artery will be acquired during baseline and FMD conditions. For FMD, reactive hyperemia will be produced by inflating a pediatric BP cuff around the forearm to 250 mmHg for 5 minutes followed by rapid deflation. |
Secondary
| Measure | Time frame | Description |
|---|---|---|
| Change in Large elastic artery stiffness and compliance at 12 months | Baseline and 12 months | transcutaneous custom tonometers (Noninvasive hemodynamics Workstation, Cardiovascular Engineering Inc., Norwood, MA) will be positioned at the aorta and femoral artery to measure aortic pulse wave velocity. |
| Change in Tubular atrophy at 12 months | Baseline and 12 months | Kidney transplant biopsies will be performed. Morphometric analysis will be performed using trichrome and Sirius Red to determine tubular atrophy. All imaging will be done using an Aperio scanner. |
| Change in participant plasma and urine complement activation fragment levels at 12 months | Baseline and 12 months | Complement activation fragments (Ba, C4a, C3a, C5a, sC5b-9) will be measured at the University of Colorado Exsera Biolab located on the Anschutz Medical Campus. |
| Change in interstitial fibrosis at 12 months | Baseline and 12 months. | Kidney transplant biopsies will be performed. Morphometric analysis will be performed using trichrome and Sirius Red to determine interstitial fibrosis. |
Countries
United States
Contacts
Primary ContactJessica Kendrick, MD MPH
Outcome results
None listed