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Low
biological value proteins:
grains & vegetables
-For
vegetarian pts or pts who can’t adhere to this, we give
supplements to
-Recent clinical research indicates that pts with CRF,
regardless of dialysis treatment or pharmacological
treatment, have the same energy expenditure as normal
individuals so can use same formulas given above to
determine energy requirements.
2)
Protein Requirements
-
Most dialysis and kidney transplant pts are diabetics
-
High protein intake increases proteinuria and decreases
Glomerular Filtration Rate in pts with CRF and
proteinuria.
- This has been shown extremely well in
diabetic patients
-
Low protein diet (<1 g/kg/day) supplemented with
essential Amino Acids or keto-analogues of these Amino
Acids has been shown to be beneficial in adult type 1
diabetic pts.
-
The advantage of ketoacid supplements is to reduce urea
production, which will decrease symptoms of uremia
-
This is a very good study. These graphs show the effects
of protein restriction in type 1 diabetic patients on
Glomerular Filtration Rate and proteinura.
-
Low Protein Diet = < 0.8g/kg/day
-
Normal Protein Diet = 1g/kg/day
-
The population was split into 2 groups: one group was
put on a low protein diet and the other group on a
normal protein diet. Quick summary: Low Protein Diet
maintains Glomerular Filtration Rate and proteinuria
-
The first graph shows that Glomerular Filtration Rate
can be maintained for 50 mos (4 years) if pt is on a Low
Protein Diet. Compare that to pts on a Normal Protein
Diet whose Glomerular Filtration Rate approaches zero by
the end of 4 years and these patients needed dialysis.
-
The second graph shows that Low Protein Diet can
maintain baseline proteinuria whereas Normal Protein
Diet will worsen proteinuria. (Note if looking at this
in black and white: darker bars are at the beginning of
study and lighter bars are at the end of either the
Normal Protein Diet OR Low Protein Diet)
-
Low protein diet is beneficial especially in DM1 and
other studies have shown similar in DM2
- Do
these rules apply to all pts or just diabetic pts??
Data is controversial. There is no solid data saying
protein restriction will be helpful in pts without
diabetes.
3)
Electrolyte Requirements
a.
Na+:
i.
Plays a major role in control of extracellular
fluid volume and hypertension.
ii.
Most RF patients have HTN and need a low Na diet
(60-100 mEq/day of Na). Be careful what you write salt
(NaCl) vs. Na. You want about 2g Na diet = 88 mEq.
2 g NaCl = 34 mEq
b.
K+:
i.
K+ restriction isn’t usually required because pts
don’t get hyperkalemic unless: pts have Glomerular
Filtration Rate < 20 ml/min, certain diabetic pts, or
pts with interstitial nephritis. This pts can develop
hyperkalemia even at Glomerular Filtration Rate of 60
ml/min due to a variety of reasons.
ii.
Dialysis patients are on K+ restricted diet
because they have no urine output and will retain all K+
until they are dialyzed and it could build up to toxic
levels
c.
Ca++:
i.
Low protein diets contain low Ca++ so they need
supplements
ii.
Patients with Glomerular Filtration Rate < 40
ml/min or dialysis pts also need supplements (1g/day)
iii.
Active vitamin D3 is 1,25 dihydroxycholeciferol.
a1
hydroxlyase is present in the kidney which converts 25
hydroxycholeciferol
à
1,25 dihydroxycholeciferol. In renal failure, the
kidneys can’t do this so you don’t make any active vit
D3.
iv.
Therefore, we give these pts active vit D3 and
Ca++ supplements
d.
PO4:
i.
Hyperphosphatemia occurs once Glomerular
Filtration Rate < 30ml/min due to retention
ii.
Hyperphosphatemia is a major factor for
hyperparathyroidism (incr PTH levels) which is a uremic
toxin
iii.
PO4 restriction like protein restriction retards
the progression of renal failure
iv.
There is a reciprocal relationship btn PO4 and
Ca++ so if you see low Ca and high PO4 DON’T GIVE Ca++!!
(unless there is a long QT interval which suggests true
hypocalcemia). You must lower phosphorous to normalize
Ca++
2)
Vitamin Requirements
a.
Dialysis removes all water soluble vitamins, but
not fat soluble ones (ADEK)
b.
Vit deficiencies can result from reduced food
intake and decreased production of Vit D3 (already
discussed)
c.
Common def – pyridoxine (B6), folic acid, and Vit
D3
d.
Supplement these pts with only water-soluble
vitamins NOT multivitamin because they contain fat
soluble vitamins
3)
Trace Elements
a.
Zinc and selenium deficiencies may occur in
dialysis pts
b.
Zinc deficiencies can occur in pts on low protein
diet or with nephrotic syndrome
c.
Zinc deficiencies tend to cause a metallic taste,
disturbed smell and altered growth; but other uremic
toxins can give metallic taste as well
d.
In males, zinc def. can = impotence and
supplement (15 mg/day) is recommended
e.
Se def. can increase oxidative stress so Se
supplements may be needed
f.
Iron
def is very common and most important
in RF patients due to loss of bld in gut, repeated bld
tests, bld left behind in dialyzer/tubing, and poor
nutrition. Give IV iron because most pts don’t tolerate
ferrous sulfate orally.
4)
Fluid Management
a.
Fluid restriction is indicated in pts with
Glomerular Filtration Rate < 20 ml/min and edema since
they can’t excrete fluid
b.
In dialysis pts, fluid intake restricted to 1000
ml/day.
c.
If pts also have CHF or liver failure in addition
to RF, we’d restrict fluids because CHF and liver
failure cause fluid retention.
Back to our case...
His
Glomerular Filtration Rate is about 25 ml/min!! This
needs to be improved!
Based on his calculated daily protein intake, what would
you do next?
A.
Advise pt to have an A-V access for dialysis in 6
mos
B.
Refer pt to dietician for further instruction on
dietary protein intake
C.
Increase dietary protein intake to compensate for
worsening proteinuria
D.
No adjustment in dietary intake at this time
E.
Increase ACE- Inhibitor dosage
Let’s say a few words about each of the options:
A.
He’s only 25 y/o! You should prevent dialysis as long
as possible. Eventually he will need it but not yet.
You need to maintain or reduce proteinuria and maintain
Glomerular Filtration Rate
C. Incr
protein used to be common practice a few years ago, but
now we know this will only increase proteinuria and
decrease overall kidney function. So instead you’d want
to decrease protein to 0.6 g/kg/d + grams lost in urine
each day. Quick calculation: say he weighed 70 kg – 70
* 0.6 = 42 g Then add the 4.8 g he loses in his urine
each day = 46.8 g/day protein for our pt
D.
Wrong answer unless you want a malpractice suit
E.
You can increase ACE-I dose but this won’t prevent the
progression of RF at this time.
B
is the correct answer! Get the dietician involved.
You can calculate his protein intake based on his urea
excretion – his protein intake was 0.9 g/kg/day
instead of 0.6. So he needs to the advised further on
how to reduce protein in diet.
Glomerular Filtration Rate can actually be increased
if patients are very strict with themselves and
control their BP, blood glucose levels, and protein in
the diet.
Kidney Stones
* Calcium oxalate or calcium
phosphate stones are the most common!
*
Struvite – triple phosphate or infection stones
Treatment for Calcium oxalate/phosphate stones
(these treatments work for all stones usually)
-
Water intake: increase to >2-3 L/day to
prevent precipitation of stones
-
Ca intake: normal to high levels of Ca. The
treatment used to be to restrict Ca, but we now know
that Ca binds to oxalate in GI tract so there is little
oxalate taken up by kidney. High calcium isn’t
necessary if you can restrict oxalate. This may be a
board question he said.
-
Na intake: Restrict to < 100 mEq/L per day
because decreased Na = decreased urinary Ca excretion
because Na and Ca are reabsorbed together. Low protein
also reduces Ca excretion.
-Purine
and vit C intake: reduced intake of both lowers
oxalate formation.
Back to the Excretory System Index
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