Protein Intake, Nutrition and Cardiovascular Diseases in Stage V CKD

Even though the National Kidney Foundation guidelines recommend a dietary protein intake of
1.2 g/kg/d in hemodialysis patients, it remains unclear whether high protein intake has
beneficial or harmful nutritional and cardiovascular effects in this population.

We hypothesize that in the dialysis population overall: (1) Protein intake is a major
determinant of muscle mass while inflammation, oxidative stress and metabolic acidosis play
a lesser role; (2) Malnutrition is not an uremic cardiovascular risk factor hence low
protein intake does not cause cardiovascular disease; and (3) In the other extreme, high
protein intake is also not a major cause of cardiovascular disease since high serum
phosphorus associated with high protein intake can usually be controlled by the use of
phosphorus binders in routine clinical practice.

The specific aims of this proposal are to examine in a prospective cohort of hemodialysis
patients the longitudinal associations of absolute total protein intake (TPI in g/day) or
dietary protein intake normalized to body weight (DPI in g/kg/day) with

1. Nutritional status (mid-thigh muscle mass as measured by Magnetic Resonance Imaging )
and functional status (6-min walk) and

2. Arterial stiffness (aortic pulse wave velocity) Understanding the relationship between
protein intake with body composition (muscle mass) and intermediate CV outcomes
(arterial stiffness) in stage V CKD patients in hemodialysis is of great scientific and
practical significance

Inclusion Criteria:

- The study will be comprised of adult (≥18 years) chronic hemodialysis patients.

- Appetite often change with initiation of dialysis and kidney function recover
sometimes from acute renal failure; hence only patients on dialysis at least for
three months will be included.

- As urinary losses of urea could affect the estimation of protein intake from the urea
kinetic modeling, we initially planned to exclude patients with urine output > 200
ml/day. However, this might exclude many potential participants. Therefore, we plan
to include those participants with UPO > 200 ml/day but willing to collect 44-hr
urine collection between dialysis treatments for measurement of urinary urea.

Exclusion Criteria:

- Patients with persistent volume overload (substantial pedal edema) despite attempts
at achieving dry weight will be excluded as hydration status might affect estimation
of muscle mass. -

- patients with inability to walk or those who use wheel-chair might have reduced
mid-thigh muscle mass despite good protein intake because of disuse, and hence these
patients will be excluded.

- Persons with pacemakers and cochlear implants are excluded because of the magnetic
field of MRI. Certain types of materials used in breast augmentation could be
affected by the strong magnetic field and hence breast augmentation is an exclusion
criteria. Artificial hips could interfere with mid-thigh muscle mass measurements
whereas lumbar spine hardware could interfere with visceral fat measurements and
hence, individuals with these will be excluded.-

- Persons > 300 lbs will be excluded because of the weight limit of the MRI table.
Atrial fibrillation could interfere with measurement of PWV.

- Patients who are unlikely or unable (in the opinion of the nephrologists, nurses or
dieticians taking care of the patient) to comply with research protocol will be
excluded.

- Patients with symptomatic heart failure, current active malignancy (excluding
squamous and basal cell skin cancers), active AIDS, chronic lung disease requiring
supplemental oxygen therapy and cirrhosis will be excluded.

- Patients enrolled in interventional trials will be excluded.