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44 Cards in this Set
- Front
- Back
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What is a kidney stone?
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a solid concretion or crystal aggregation formed in the kidneys from dietary minerals in the urine
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What are some lifestyle factors that contribute to stone incidence?
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High protein intake
Obseity Diabetes and metabolic syndrome |
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What is the number one clinical feature of a kidney stone?
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PAIIIN!!!
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Fever implies what wrt to a stone?
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Concomitant infection and risk of sepsis (Not a good thing!!!!)
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How are most kidney stones passed?
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Spontaneously
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What are the 4 types of stones?
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1. Calcium oxalate and calcium phosphate (75%)
2. Uric Acid 3, Infection stones 4. Cystine |
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What do calcium oxalate crystals look like?
Uric acid crystals |
Calcium Oxalate: "back of an envelope"
Uric Acid: Ugly: rhomboid, football shaped |
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What do struvite crytals look like?
Cystine crystals? |
Struvite: prisms or coffin lids
Cystine: hexoganal plates |
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How do stones get started?
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They must be adherent somewhere in the kidney or they would simply was away
One possibility is Randall's plaques which are attached to the papilla Or perhaps crystals adhere to the luminalsurface of injured renal tubular cells |
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The activity of crystals is roughly proportional to what?
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Concentration
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The activity product must exceed what for stone formation to begin?
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Saturation
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What is the upper limit of metastability?
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Formation product - above this and you start forming stones
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What is the most important small molecule inhibitor of stones and how does it work?
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Citrate - forms soluble complex with calcium and so keeps calcium ions from participating in nucleation and crystal growth
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What 3 items is a risk factor for calcium stone formation?
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- hypercalciuria
- hyperoxaluria - low urine volume |
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What are 3 promoters, that when increased are a risk factor for stone formation?
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1. Hyperuricosuria (excess uric acid in the urine)
2. alkaline urine pH (calcium phosphate) 3. Acid urine pH (uric acid stones) |
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If what inhibitor is low can cause a stone?
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Citrate (hypocitraturia)
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What level of urine volume is a risk factor for crytalloid formation?
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low urine volume - increases crystalloid concentrations
Happens in warm environment |
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Hypercalcuria is what type of risk factor?
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A GRADED risk factor - the lower the calcium the lower the risk of stone formation
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What is the main causes of hypercalciuria?
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Idopathic
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What 2 items are increased in the pathogenesis of idiopathic hypercalciuria?
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Vitamin D activation
Post prandial fractional excretion of calcium |
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Increased Vitamin D could mediate calciuria how?
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By stimulating intestinal calcium absorption and stimulating bone resorption
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A diet high in what can cause hypercalcuria?
How? |
High salt diet inhibits PT Na and (thus) Ca absorption
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What type of diuretic enhance PT Ca absorption and thus ameliorate hypercacluria?
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Thiazide diuretics
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How does dietary calcium intake affect stone risk?
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INCREASING CA actually decreases risk
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What compoun is a metabolic end product without physiologic function that has equivocal role in idiopathic calcium stone formation?
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Oxalate
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Enteric hyperoxaluria occurs in patients with what?
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Fat malapsorption
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How does enteric hyperoxualuria get created?
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Intestinal malabsorption increases FF in intestinal lumen and FFA binds Ca in insoluble "soaps"
When Ca is unavailable to bind oxalate, it is hyperabsorbed in the colon |
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What is the treatment of hyperoxaluria?
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Paradoxically, increased Ca intake
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Hypocitraturia is due to what?
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Due to acidosis, which increases renal citrate catabolism
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What are 5 causes of hypocitraturia?
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1. High protein diet
2. dRTA - carbonic anhydrase inhibitors 3. K depletion 4. Renal insufficiency 5. Diarrhea (loss of alkali) |
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What are the 2 main risk factors for uric acid stones?
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1. Persistently acidic urine - often due to defect in urinary ammonia production (insulin resistance, gout, diarrhea/ileostomy) (80%)
2. Hyperuricosuria (20%) |
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What is the main treatment of uric acid stones?
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Alkalize the urine BROOO!!!
K citrate (alkali) is the most effective treatment |
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What is the most severe form of nephrolithiasis?
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Infection stones: associated with sepsis and renal failure
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What is the mechanism for infection stone?
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Organism creates urease which breaks down into ammonia --> makes urine alkali --> leads to struvitie stone formation
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What causes cystine stones?
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Inherited defect of renal tubular AA reabsorption
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What test is positive is cystine stones?
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Nitroprusside test
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What is the treatment for cystine stones?
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High fluids (4L/d!!)
Alkali --> K citrate Penicillamine, tiopronin |
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What is a good diet for someone with nephrolithiasis?
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High fluids
Moderate calcium Low oxalate low salt and animal protein for hypercalcuria |
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What is one of the main pharmacologic treatments for calcium nephrolithiasis?
How do they work? |
Thiazide diuretics - anticalciuric action in the PT
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What must be done concomitantly with thiazides?
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Na restriction
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What are the indications for a thiazide?
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Hypercalcuria
Hypertension |
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What are adverse events with a thiazide?
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K depletion
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What else can be used to treat nephrolithiasis?
What is its MOA? |
Potassium citrate
MOA is to increase urine citrate (alkali effect) Increase urine pH (uric acid stones) Reduce urine calcium |
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What is potassium citrate ideal for?
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Mixed calcium and uric acid stones
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