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Surgery

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Urology

Question
89 out of 129
 

A patient with complaints of passage of recurrent stones for the past 10 yrs. All is given as advice for diet except (AIPG 2010)



A Protein restriction
B Calcium restriction

C Salt restriction
D High In take of water

Ans. B Calcium restriction (REF. SABISTON SURGERY 18TH ED)

It may include dietary modifications and medication with the goal of reducing excretory load on the kidneys:

a. Drinking enough water to make 2 to 2.5 liters of urine per day.

b. A diet low in protein, nitrogen and sodium intake

c. People with urinary tract infections, kidney disorders such as cystic kidney diseases, and certain rare, inherited metabolic disorders are also more likely to develop kidney stones.

d. Restriction of oxalate-rich foods, or consumption of more calcium

e. Taking drugs such as thiazides, potassium citrate, magnesium citrate and allopurinol, depending on the cause of stone formation.

f. Some fruit juices, such as orange, blackcurrant, and cranberry, may be useful for lowering the risk factors for specific types of stones

g. Limit intake of caffeinated beverages, such as coffee.

h. Avoidance of cola beverages.

i. Avoiding large doses of vitamin C

For those patients interested in optimizing their kidney stone prevention options, a 24 hour urine test can be a useful diagnostic.

Oxalate and calcium balance

a. Since oxalatesform the basis of one type of kidney stone, one prevention strategy is to restrict consumption of oxalate-rich foods such as chocolate, nuts, soybeans, rhubarb,and spinach.

b. Stones are formed when oxalates bind with calcium, but calcium plays a vital role in body chemistry and limiting calcium may be unhealthy.

c. Diet that includes recommended calcium levels prevents kidney stones in men better than a low-calcium diet.

Diuretics

a. One of the recognized medical therapies for prevention of stones is thiazides, a class of drugs usually thought of as diuretics.

b. These drugs prevent calcium stones through an effect independent of their diuretic properties: they reduce urinary calcium excretion.

c. Thiazides work best for renal leak hypercalciuria - a condition in which the high urinary calcium levels are from a primary kidney defect.

Allopurinol

a. Allopurinol (Zyloprim) is another drug with proven benefits in some calcium kidney stone formers.

b. Allopurinol interferes with the liver's production of uric acid.

c. Uric acid stones are more often caused by a combination of high urine uric acid and low urine pH.http://en.wikipedia.org/wiki/Kidney_stone - cite_note-pmid11676906-39

d. Therefore prevention of uric acid stones relies on alkalinization of the urine with citrate(in the form of Shohl's solution (sodium citrate), sodium bicarbonate, potassium citrate, potassium bicarbonate or acetazolamide, a carbonic anhydrase inhibitor).

e. Allopurinol is reserved for patients in whom alkalinization is difficult. For patients with increased uric acid levels and calcium stones, allopurinol is one of the few treatments that has been shown in double-blinded placebo controlled studies to actually reduce kidney stone recurrences.

Decreased-protein diet

a. A high-protein dietmight be partially to blame. Protein from meat and other animal products is broken down into acids, including uric acid.

b. The most available alkaline base to balance the acid from protein is calciumphosphate (hydroxyapatite) from the bones (buffering).

c. High protein intake is therefore associated with decreased bone density as well as stones.

d. The acid load is associated with decreased urinary citrate excretion; citrate competes with oxalate for calcium and can thereby prevent stones.

Other modifications

a. Potassium citrateis also used in kidney stone prevention. This is available as both a tablet and liquid preparation.

b. The medication increases urinary pH (makes it more alkaline), as well as increases the urinary citrate level, which helps reduce calcium oxalate crystal aggregation.

c. Optimal 24 hour urine levels of citrate are thought to be over 320 mg/liter of urine or over 600 mg per day.

Urology Flashcard List

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