Dietary Sodium Intake and Blood Pressure in Living Kidney Donors

This is a pilot study to determine the feasibility of the study design and examine the main outcome whether low dietary sodium intake <2.3 g/day (<100 mmol/day) is superior to high dietary sodium intake ≥4 - <6 g/day (≥174 - <261 mmo/day) in controlling blood pressure (BP) to be within normotensive range, lowering systolic and diastolic blood pressures (SBP and DBP) from the baseline blood pressures, and decreasing the risk of hypertension, worsening kidney function, and proteinuria in living kidney donors between 5 and 12 months after living kidney donation?.

• Dietary sodium (Other): Low sodium diet with sodium of <2.3 g/day (<100 mmol/day) and high sodium diet with sodium of ≥4 - <6 g/day (≥174 - <261 mmo/day)

Primary outcomes

• Change in systolic and diastolic blood pressure from baseline to post-treatment between the two treatment groups [4 weeks after dietary intervention pre-crossover and 4 weeks after dietary intervention post-crossover]: Change in systolic and diastolic blood pressure from baseline to post-treatment between the two treatment groups, adjusting for patients' demographic and clinical differences (age, gender, BMI, and comorbidities) between the two treatment groups

Secondary outcomes

• Hypertension [4 weeks after dietary intervention pre-crossover and 4 weeks after dietary intervention post-crossover]: New-onset hypertension defined as systolic blood pressure >/= 130 or diastolic blood pressure >/=80 mmHg
• Worsening kidney function [4 weeks after dietary intervention pre-crossover and 4 weeks after dietary intervention post-crossover]: Increased estimated glomerular filtration rate (eGFR) >/= 25 ml/min/1.73 m2 or increased serum creatinine >/= 0.3 mg/dL
• Worsening proteinuria [4 weeks after dietary intervention pre-crossover and 4 weeks after dietary intervention post-crossover]: Increase in urinary albumin excretion rate (AER) ≥30 mg/day
• Proteinuria [4 weeks after dietary intervention pre-crossover and 4 weeks after dietary intervention post-crossover]: New-onset urinary albumin excretion rate (AER) ≥30 mg/day

Sex: All, ages: 18 Years to any, accepts healthy volunteers

Inclusion Criteria:

* Living kidney donors who underwent a living kidney donation at least 5 months ago but not more than 12 months
* Age ≥18 years old
* Agree to perform the procedure as per study protocol (Table 1)
* Living kidney donors with an average sitting SBP <160 mmHg at 5-month post-donation measured by automatic office blood pressure (AOBP)
* Able to sign informed consent
* Able to attend all research visits
* Woman using birth control methods other than hormonal contraception

Exclusion Criteria:

* History of previous cardiovascular (CV) events including acute MI, HF, and stroke
* Symptomatic heart failure within 5 months after living kidney donation or left ventricular ejection fraction (by any method) <35%
* CV event or procedure or hospitalization for hypertensive-related disorders within 5 months after living kidney donation
* Diagnosed with HTN or on antihypertensive medication(s) before living kidney donation
* Patients who are supposed to take BP lowering medications for reasons other than BP control but do not take those medications or take them with in appropriate doses
* Arm circumference is too small or large to allow accurate BP measurement with available 24-h ABPM machines.
* An average standing SBP ≥160 mmHg at 5-month post-donation measured by automatic office blood pressure (AOBP)
* Albuminuria that equals or is equivalent to 1 g per day by using spot urinary albumin per urine creatinine ratio (UACR) or 24-hour urinary albumin excretion rate by a 24-hour urine collection within 5 months post-donation
* Advanced kidney function defined by estimated glomerular filtration rate (eGFR) by using Chronic Kidney Disease Epidemiology Collaboration (CKD-EPI) equation22 of <20 ml/min/1.73m2 or requiring dialysis after living kidney donation
* Drink coffee > two 8-ounce (237 mL) cup a day or equivalence
* Drinks alcohol >3 drinks/day or >30 ml/day
* Smoking cigarette ≥10 cigarettes/day
* Take Nonsteroidal anti-inflammatory drugs (NSAIDS)
* Use hormone replacement therapy or oral contraceptives
* Pregnancy, currently trying to become pregnant
* Using birth control pills
* A medical condition likely to limit survival to less than 2 years
* Any factors that are likely to limit adherence to interventions. For example,

  * Living kidney donors who cannot come to follow up regularly per study protocol to logistically collect data from enrolled participants.
  * Active alcohol or substance abuse within the last 5 months of living kidney donation
  * Plans to move outside the clinic catchment area in the next 4 months without the ability to transfer to come to follow up at SPLID study site.
  * Significant history of poor adherences with medications or attendance at clinic visits
  * Significant concerns about participation in the study from spouse, significant other, or family members
  * Lack of support from primary health care provider
  * Residence too far from the study clinic site such that transportation is a barrier including persons who require transportation assistance provided by the SPLID clinic funds for screening or randomization visits
  * Residence in a nursing home or an assisted living
  * Clinical dementia with or without treatment with medications and cognitively unable to follow the protocol
  * Other medical, psychiatric, or behavioral factors that may interfere with study participation or the ability to follow the intervention protocol
  * Inability to obtain informed consent from participant
  * Living in the same household as an already randomized SPLID participant

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• Ekamol Tantisattamo, MD, MPH, Principal investigator, University of California, Irvine