Transcript Document

Lecture 8b 24 February 2014
Renal Disease
Kidney stones
Affect about 50,000 Canadians each year
Mostly males over the age of 20 years
Kidney stones occur because of urinary
concentration of components making up the stones
is right to form the stones. The components are:
-calcium, oxalate and phosphate
-oxalate is the salt of oxalic acid (eg
calcium oxalate)
-oxalic acid comes from vitamin C
metabolism
-most common stones are calcium oxalate and
calcium oxalate combined with phosphate
-less common stones are comprised of :
-uric acid (from purine metabolism (purine is
part of the nucleotide bases)),
-the amino acid cystine
-or magnesium ammonium phosphate
Get excess calcium, uric acid and cystine in the
urine due to:
-excess urinary calcium caused by overly efficient
calcium absorption in the intestine or overly efficient
calcium excretion in the urine
-uric acid stones caused by gout –gout causes build up
of uric acid in the blood and urine
-cystine buildup in the urine caused by an inherited
disorder called cystinuria in which renal tubules are
unable to reabsorb amino acid cystine-get abnormally
high concentrations of cystine in the urine-then get
crystallisation followed by stone formation
Magnesium ammonium phosphate stones
-magnesium ammonium phosphate stones
(struvite) caused by repeated urinary tract
infections
-bacterial enzymes cause struvite formation
-cranberry juice may limit struvite formation
in females ( limited number of studies done)
Nutritional prevention of kidney stones
- to prevent in the first place drink lots of fluid
- to prevent a recurrence-consume 3-4 litres of fluid
(mostly water) each day (possibly more in warm
climates) to produce 2-2.5 litres of urine daily-why
?
-people with fevers, diarrhea or vomiting need
more fluid why?
Nutritional prevention of calcium oxalate kidney
stones
-for people who have never had a stone, an
intake of calcium(800 mg male, 1200 mg
female/day) may lower risk but not if high
oxalate foods are taken with calcium
Nutritional prevention of kidney stones (table 28-9)
-high oxalate foods include:
-beans- green and wax
-beets*
-celery
-leeks
-legumes
-blackberries
-blueberries
-raspberries
-spinach*
Nutritional prevention of kidney stones
-rhubarb*
-strawberries*
-chocolate and chocolate beverages*
-nuts, nut butters*
-tea*
-wheat bran*
-cocoa
-coffee
-nuts
* documented to raise urinary oxalate- avoid if at
risk of oxalate stones
Nutritional prevention of kidney stones
- people with hypercalcuria should avoid
excessive calcium intakes
-but not below recommended
intakes or get calcium removed
from bone
- avoid excessive vitamin C intakes ( in excess
of recommended intakes)- why?
Nutritional prevention of kidney stones
-to prevent uric acid stones -diets restricted in
purines
eg red meats
in particular- organ meats,
anchovies,sardines and meat
products)- this is unproven
but suggested
- prevent cystinuria by limiting methionine intake
–why?
Nutritional treatment once a stone has formed
- once a stone has formed drinking plenty of
fluid may help it pass
- people with calcium oxalate stones should
avoid high oxalate foods
Nephrotic syndrome
-not a disease but a distinct cluster of
symptoms caused by damage to the
glomerular capillaries
-damage due to diabetes, hypertension,
infections (kidneys and elsewhere),
immunological and hereditary disorders,
chemicals (medications, illicit drugs or
contaminants) and some cancers –there are
others; this is only a partial list
Nephrotic syndrome
-consequences
-loss of blood proteins to urine
-edema-retention of sodium
-altered blood lipids-elevated cholesterol,
triglycerides, LDL, VLDL, Lp(a)
-platelets clot more easily
Nephrotic syndrome
Treatment via diet:
-ensure adequate energy intake- (35 kcal/kg body
weight/d) as this sustains weight and spares
proteins
-if have accompanying weight loss or infections
then one needs more energy to fight the weight loss
and the infections
-if obese, lose weight to control lipids and blood
glucose as elevated blood lipids and blood glucose
will exacerbate nephrotic syndrome
Nephrotic syndrome
Treatments via diet
-watch protein intake ( about 0.8 g/kg body
weight/day –no more than 1.00 g/kg body
weight/day)- protein must be from high
quality protein sources
-dietary fat- TLC diet first then antilipemic
drugs
Nephrotic syndrome
Treatment via diet
-sodium-restricted due to sodium retention as
the kidney is not clearing sodium as well
compared to the healthy person (sodium
restriction depends on response to diuretics
but generally 1-2 g of sodium per day)
Table 28-1