Chapter 9
Renal Disease
Functions of Kidneys
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Help maintain proper metabolism and
hormonal balance
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Converts the inactive form of vitamin D2 into
the active
form D3
Produces the enzyme renin, which affects
blood pressure
Produces erythropoietin, which stimulates red
blood cell production in the bone marrow
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Other Functions
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Reabsorbing important body constituents,
such as electrolytes
Excreting toxins and waste material
through the 1 million nephrons
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Diagnosis of Renal Disease
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High creatinine clearance, as indicated with a
24-hour urine collection, is one of the first
indicators of renal stress; low creatinine clearance
reflects diminishing capacity of the kidneys to filter
waste and toxins
Proteinuria is another early indicator of renal
disease
Elevated blood urea nitrogen (BUN)
Elevated serum creatinine—a normal compound
found in muscle that the kidneys regulate
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Main Types of Renal Diseases
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Glomerulonephritis, nephritis: an inflammatory state of the
glomeruli; can develop into nephrotic syndrome; can be
caused by autoimmune disorders, creatine supplements as
used by athletes (Thorsteindottir et al., 2006). Symptoms
include HTN, edema, changes in urine color, nausea and
vomiting, headaches
Nephrotic syndrome: involves the loss of the glomerular
barrier to protein with resulting loss of protein into the urine
(microalbuminuria: loss of albumin in the urine between 20
and 200 mcg/min). Up to 0.15 g PRO excretion daily is
normal
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ACE inhibitors (blood pressure Rx) helps preserve renal
function
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Types of Renal Diseases
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Glomerulosclerosis, nephrosclerosis—related to
scarring of the glomeruli found within the
nephrons
End-stage renal disease (ESRD)—associated
with macroalbuminuria (>200 mcg albumin in the
urine)
Renal stones, or nephrolithiasis
Nephropathy or diabetic nephropathy—involves
correlates of the metabolic syndrome; screening
for microalbuminuria at onset of type 2 diabetes
advised and every 5 years thereafter for either
form of diabetes
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Factors Related to Increased
Risk of Nephropathy
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Genetics
HTN—goal to maintain BP <120/80
Hyperglycemia—goal to maintain A1c <7%
Smoking
Older age
Male gender
High-protein diet (Ayodele et al., 2004)
UTIs—found with high BG; include cranberry juice in
moderation
Orlistat with associated fat malabsorption (Singh et al., 2007)
Contrast dyes (Iyisoy et al., 2008)
Iga nephropathy—may be due to untreated celiac (La Villa et al.,
2003)
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Acute Renal Failure
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Occurs with a sudden decrease in
glomerular filtration rate (GFR)
May be short-lived with symptoms
treated—low potassium diet, low protein
May occur due to rhabdomyolysis from
statin medications or undue muscular
stress (trauma from excessive weight
lifting), infection, severe dehydration,
hypotension
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Signs and Symptoms
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Albumin <3.0 mg/dL found with:
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Peripheral edema
Ascites (abnormal fluid accumulation in the
abdominal cavity)
Anasarca (generalized massive edema)
*Edema caused by fluid leakage into the
interstitial space, resulting in low blood volume
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Effects of Loss of Protein
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Reduced vitamin D-binding proteins, leading to depletion of
active vitamin D and osteomalacia (soft bones)
Renal osteodystrophy is a complex metabolic disorder that
causes
poor bone development in children and osteoporosis in
adults; due
to high serum phosphorus, hypocalcemia, altered
parathyroid (PTH) function
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Newer term: Chronic kidney disease–mineral and bone
disorder (CKD-MBD); also related to impaired vitamin D
metabolism and includes calcification of the vascular
system/soft tissues (Moe et al., 2007)
Hyperlipidemia resulting from loss of lipid-carrying proteins
Increased risk of thrombosis because of decreased
anticlotting factors
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Treatment of Nephritis
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Reduce protein intake as needed per
serum lab values
Mild potassium restriction may be
appropriate
Mild sodium restriction (food label
guideline of 2400 mg/day is appropriate)
Inclusion of omega-3 fats may be helpful
to reduce inflammation
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Treatment of Nephrotic Syndrome
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Improve poor protein status resulting from the loss of protein
in the urine (need increased PRO and kilocalories); increase
PRO as tolerated with lab assessment
Slow weight loss is indicated with HTN and obesity, or for
individuals with the metabolic syndrome
Edema associated with low serum albumin levels should
NOT be treated with excess restriction of sodium intake; aim
for food label guideline of 2400 up to 3000 mg/day
Aim for positive nitrogen balance with emphasis on highbiologic protein (meat, eggs, milk) and adequate kilocalories
to prevent weight loss
Inclusion of omega-3 fats may reduce inflammation
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Treatment of Nephrosclerosis
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Decrease homocysteine levels with
increased B vitamins: B2, B6, B12, and
folate
Avoidance of toxic substances:
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Certain medications and painkillers
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Treatment of Diabetic Nephropathy
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Aim for normalized blood glucose levels to extend
renal function (HgbA1c <7.2% associated with
50% reduced risk of kidney disease progression)
Follow TLC diet with type 2 diabetes along with
inclusion of omega-3 fats and increased exercise;
increased fiber intake helps promote nitrogen
excretion through the feces
Sodium restriction with HTN: BP goal <125/75
with chronic renal failure (CRF) and proteinuria
Restrict protein to maximum of 0.8 g/kg BW with
macroalbuminuria
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Signs and Symptoms of CKD
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Creatinine clearance <70 mL/min
Hyperkalemia (high serum potassium) and
hypernatremia (high serum sodium)
Fluid retention with edema
Imbalances of serum calcium (low) and serum
phosphate (high)
Anemia—verify form; may be reduced
erythropoietin or actual iron deficiency or other
cause such as anemia of chronic disease (related
to inflammation), treat accordingly
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Treatment of CKD
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Low-phosphate diet to control serum
phosphate level
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Milk restriction (1 to 2 cups/day) because of
high phosphate content
Provide calcium supplements after serum
phosphate level normal; up to 2 g Ca++
(including Ca++ content of phosphate binders)
2-g sodium diet if albumin normal
Maximum 0.8 g PRO/kg BW
High-fiber diet helps bind and excrete
excess nitrogen with fecal loss
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Role of Exercise
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Helps lower insulin resistance and control
BG and BP
Helps reduce cardiovascular disease
associated with CKD
Helps maintain quality of life
Improves variety of health outcomes
associated with CKD (Chan et al., 2007)
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End-Stage Renal Disease (ESRD)
or Chronic Renal Failure
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Associated with severe loss in the
glomerular filtration rate and may be
associated with oliguria (severe reduction
in urine production) or anuria (no urine
output)
Fluid restriction required with reduced
urine output
Dialysis or renal transplant is warranted at
this stage of renal disease
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Dialysis Issues
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PRO goal ≥1.2 g/kg BW
Aim for dry weight stabilization (weight after
dialysis when BP normal), between dialysis
sessions (interdialytic weight gain) with fluid
restriction as needed
Supplement with water-soluble vitamins
Supplement with Ca++ (when phosphate normal)
and active form of vitamin D (D3)
Consider zinc and magnesium supplements
Undertake iron studies to rule out need for FeSo4
Consider carnitine and branched-chain amino
acid supplementation (Cano et al., 2006; Savica et al., 2004; Tanner et al.,
2008)
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Renal Transplantation
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Decreased kilocalories because of steroidinduced weight gain
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But adequate kilocalories to maintain PRO anabolism
Moderate sodium restriction and adherence to
DASH diet to control HTN
Consider supplementation with thiamin, especially
with delayed graft function (Klooster et al., 2007)
Consider supplementation with other B vitamins to
reduce hyperhomocysteinemia and CVD (Biselli et al.,
2007)
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Nephrolithiasis (Kidney Stones)
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Increasing in frequency, believed due to
rise in obesity rates
Increase in fluid intake (water) is most
useful to keep urine dilute
Dietary restrictions must be based on the
type of kidney stone; referral to a
registered dietitian is essential to ensure
adequate nutritional status is maintained
with food restrictions
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Calcium Oxalate Stones
(Most Common Form)
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Increased frequency found among persons with
Roux-en-Y bariatric weight loss procedure
Increased frequency found with use of Orlistat
and fat malabsorption
Increase fluid intake
Decrease oxalate intake
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Avoid excess vitamin C because it results in oxalate
formation; increase magnesium (milk; fatty fish also
beneficial and rich in magnesium)
Legumes, nuts, dark-green leafy vegetables, berries,
citrus fruits
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Calcium Oxalate Stones
(Most Common Form) (continued)
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800 to 1200 mg calcium (2.5 to 4 cups milk or
equivalent milk products)
Mild sodium restriction
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Uric Acid Stones
(Second Most Common Form)
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Often found with type 2 diabetes
Goal to reduce urine acidity
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Moderate PRO intake
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With potassium citrate or calcium carbonate
Decrease intake of meat, eggs, legumes,
grains
Increase intake of milk and milk products
Increase fruit intake
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Except cranberries and plums/prunes
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Renal Disease and Dietary Guidelines
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Goal to maintain weight or achieve slow weight
loss
May need to increase intake of fats and sugars
for kilocalories while meeting PRO goals
Emphasize monounsaturated and omega-3
fats to manage hyperlipidemia
Emphasize fruits and vegetables low in
potassium
Regular exercise advised
Moderate Na+ intake; DRI: 2300 mg Na+
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