Transcript MNT for Renal Disorders

MNT for Renal Disorders
ND 437/537
Chapter 39
Karen White, MS, RD, LDN
Renal Outline
Functions of the kidneys
 Normal urine output
 Nephrotic syndrome
 Nephritic Syndrome
 Acute renal failure
 ESRD & Characteristics of renal failure
 Dialysis & lab values for assessment with
ESRD
 MNT
 Kidney stones

Functions of the Kidneys
Filtration of blood: remove fluid and wastes
(NH3, urea, Cr, P, Na, K, H+, water)
 maintain blood pressure: secrete renin (in
response to  BV) to stimulate the
angiotensin system (vasocontstriction), 
aldosterone (Na reabsorption)   BP
 secrete erythropoietin - a hormone needed
for rbc production
 Ca-P homeostasis by activating vitamin D &
excreting Ca & P
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Filtration
Filtration:
1. filtration (into tubules)
2. reabsorption
3. secretion
– 125 ml ultrafiltrate made per
minute
– 124 ml reabsorbed
– 1 ml urine per minute x 60 x
24 = 1500 ml urine/d
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kidneys control the
amount of water,
electrolyes, acid, P, &
Nitrogenous wastes
excreted
our 3L of blood is filtered
over & over 500x/d!
Filtration, continued
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Each kidney has ~ 1 million nephrons, which consist
of the glomerulus connected to tubules
Glomerulus = capillary mass surrounded by a
membrane, Bowman’s capsule.
Glomerulus produces 180 L ultrafiltrate/d, which the
remaining tubules modify through reabsorption &
secretion.
Ultrafiltrate  blood – blood cells & proteins
Filtration is passive & relies on perfusion pressure
Tubules reabsorb most of ultrafiltrate, leaving 1.5L
urine/d. Reabsorption is active.
Urine Production - Filtration, cont.
Normal glomerular filtration rate (GFR)
125ml/min
 Urine can be very dilute (50 mOsm) or very
concentrated (1200 mOsm) depending on the
concentration of wastes in the blood and the
amount of water in which to dilute the waste
 Minimum urinary volume to excrete wastes of
a fixed concentration (600 mOsm) is 500 ml!
 Urine output of < 500ml/d = oliguria
 Anuria = no urine output (< 50ml/d)
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Glomerular Diseases
Nephritic Syndrome aka
glomerulonephritis
 Nephrotic syndrome
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Both of the these
conditions are characterized
by an impairment in the
integrity of the glomerulus,
which allows inappropriate
components to pass into
the filtrate & thus the urine.
Renal failure, in contrast, is
a decrease in the ability to
filter blood.
Nephritic Syndrome (glomerulonephritis)
inflammation of capillary loops of glomerulus.
 Characterized by:
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– hematuria - loss of glomerular barrier to blood cells,
– HTN
– mild  renal fxn
Etiology: streptococcal infection is most common.
 usually completely resolve (quickly), but can
progress to nephrotic syndrome or even ESRD.
 MNT: Na restriction with HTN. Otherwise, maintain
good nut'l status & hope it resolves.
NO need to restrict protein or potassium (K).
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Nephrotic Syndrome
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Loss of the glomerular
barrier to protein. (Filter's
holes became too large)
Characterized by
proteinuria,
hypoalbuminemia, edema &
hyperlipidemia.
Dx by proteinuria
Etiology: diabetes, lupus,
amyloidosis, & other
diseases of the kidneys.
Can be chronic, and
occasionally can progress to
CRF.
MNT: goal is to replenish
albumin w/o exacerbating
proteinuria.
 0.8 gm/kg – ¾ HBV
  calories (35cal/kg+)
  Na mildly (2400 - 3000
mg/d) with edema
 normal fluid b/c blood vol 
with  albumin
 if chronic,  saturated fat.
 can give albumin IV.
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Acute Renal Failure (ARF)
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Sudden  in GFR & thus  ability of kidneys to
excrete wastes.
Can occur with oliguria or a normal urine flow!
Duration: few days – several weeks
mortality: varies greatly depending on cause: very
low with drug toxicity, up to 70% with trauma or
sepsis.
causes: see Box 39-1 pg. 967 (severe dehydration,
trauma, sepsis, toxicity from drugs,
glomerularnephritis, obstruction d/t prostate cancer
or hypertrophy, etc.)
ARF – typical progression
1.
2.
Anuria or oliguria
Recovery
1. Increase in urine output, but still not filtering
wastes
2. Gradual recovery in waste filtration & excretion
MNT for ARF
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protein:
– oliguric phase -  (0.5 - 0.8)
– diuretic phase or dialysis - (0.8 - 1.0)
calories: 30-40 cal/kg of dry weight
 fluid, Na, K
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(fluid retention)
mEq = mg  atomic wt x
valence
 fluid: output + 500ml (monitor I/O!) atomic wt of Na = 23
 Na 500mg - 1g (20-40 mEq) -------- atomic wt of K = 39
– oliguric phase 
 K 1200 - 2g (30-50 mEq)
– diuretic phase - replace losses (monitor labs; gradually
progress to normal diet)
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Patients often “fed” parenterally initially when N/V
Progressive Nature of Renal Failure
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Once 2/3 - ¾ of kidney function is lost,
further loss will ensue, and ESRD is
unavoidable.
Sometimes progression to ESRD is rapid
Other times progression can take months –
years, with persons in pre-end-stage renal
disease for a long time.
90% of ESRD is caused by:
1. DM
2. Glomerulonephritis
3. HTN
Characteristics of Chronic Renal
Failure (CRF)
fluid retention (edema)
 Na, K (irregular
heartbeat)
  H - acidosis
  BP
  Hct (anemia)
  vit D conversion
 renal osteodystrophy:
Calcium pulled from bones
(b/c  Ca abs & to P
balance with  P excretion),
 Ca & P precipitate and are
deposited on blood vessels!
  BUN, Cr, NH3
- build up
of N2 wastes = azotemia 
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uremia:
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Malaise, weak
N/V
muscle cramps, itching
anorexia, dysguesia
neurologic/cognitive
impairment.
– Happens when BUN > 100, Cr
10-20.
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Cr > 8 qualifies for dialysis
(6 if DM)
Correlates with GFR < 10
ml/min.
Medical Treatment for ESRD
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Transplant
 Hemodialysis
– blood passes through semiDialysis: separating substances
in a solution by selective
diffusion using semi-permeable
membrane.
– Hemodialysis
– Peritoneal dialysis
 CAPD
 CCPD – multiple exchnages
at night by a machine; one
exchange during the day
permeable membrane of
artificial kidney & waste
produces are removed by
diffusion. 3-5 hours 3x/wk
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Peritoneal dialysis
– diffusion carries wastes from
the blood through the semipermeable peritoneal membrane
and into dialysate solution that
is infused into the peritoneal
cavity. The dialysate = sugar
water. CAPD - exchange
solution 4-5x/d everyday. More
efficient but less common
Hemodialysis vs. Peritoneal dialysis
MNT for Pre-ESRD,
Hemodialysis, Peritoneal Dialysis
Pre-ESRD
Hemodialysis
CAPD or CCPD
Energy
(kcal/kg IBW)
Phosphorus
(mg/kg IBW)
Sodium
(mg/d)
Potassium
(mg/kg IBW)
Fluid
(ml/d)
35-40
30-35
25+
8-12
<17
<17
1000-3000
2000-3000
2000-4000
Unrestricted
~ 40
Unrestricted
Unrestricted
500-750 +
urine output
(1000 if anuric)
2000 +
Calcium
(mg/d)
1200-1600
based on serum
level
based on serum
level
In General
most strict
Protein (g/kg)
0.6-0.8
1.0-1.2
1.2-1.5
most liberal
Monitor Patient Status
1. BP >140/90
2. Edema
3. Weight changes
4. Urine output
5. Urine analysis:
—Albumin
—Protein
Monitor Patient Status—
cont’d
6. Kidney function
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creatinine clearance
Glomerular filtration rate (GFR)
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BUN 10 to 20 mg/dl (<100 mg/dl)
Creatinine 0.7 to 1.5 mg/dl (10-15 mg/dl)
Potassium 3.5 to 5.5 mEq/L
Phosphorus 3.0 to 4.5 mg/dl
Albumin 3.5-5.5 g/dl
Calcium 9-11 mg/dl
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See table 39-5 p 977-979 for more info on lab values
7. Blood values
Kidney Transplant
1. Types: related donor or cadaver
2. Posttransplant management:
Corticosteroids
Cyclosporine
3. Diet while on high-dose steroids:
1.3 to 2 g/kg BW protein
30 to 35 kcal/kg BW energy
80 to 100 mEq Na
4. Diet after steroids:
1 g/kg BW protein
Kcal to achieve IBW
Individualize Na level
Kidney Stones - Nephrolithiasis
1.
2.
3.
Ca salts (Ca oxalate or Ca phosphate)
Uric acid
Cystine
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Ca salts —Rx: high fluid; evaluate calcium
from diet; may need more!
Calcium intake & kidney stones inversely
related!
low-oxalate diet may be needed (avoid
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rhubarb, spinach, strawberries, chocolate,
wheat bran, nuts, beets & tea) Apndx 45
acid-ash diet is sometimes useful but not
proven totally effective
Kidney Stones—cont’d
4. Uric acid stones
Alter pH of urine to more alkaline
Use high-alkaline-ash diet
5. Cystine stones (rare)
Acid-Ash Diet
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Increases acidity of urine (contains chloride,
phosphorus, and sulfur)
Meats, cheese, grains emphasized
Fruits and vegetables limited (exceptions are
corn, lentils, cranberries, plums, prunes)
Alkaline-Ash Diet
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Increases alkalinity of urine (contains
sodium, potassium, calcium, and
magnesium)
Fruits and vegetables emphasized
(exceptions are corn, lentils, cranberries,
plums, prunes)
Meats and grains limited
Pyelonephritis (UTI)
High fluid intake
 Cranberry juice can decrease bacteria
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Foods high in potassium
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Fruits and vegetables
– potatoes, legumes, greens, oranges, banana,
watermelon, dry fruits, cantaloupe, avocado