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36 Cards in this Set
- Front
- Back
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Stones are more common in adult men or women?
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Men:Women :: 2-3:1
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What is the transit time of urine through the nephron?
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5-7 minutes
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What are the natural stone inhibitors found in urine?
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Magnesium, citrate, Tamms Horsfall protein, nephrocalcin, uropontin, bikunin
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List four ways that citrate prevents calcium oxalate and phosphate stone formation.
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1. Complexes with calcium to reduce its availability to oxalate or phosphate. 2. Directly inhibits spontaneous precipitation of calcium oxalate and agglomeration of crystals. 3. More potent activity in reducing calcium phosphate growth. 4. Prevents heterogeneous nucleation of Ca oxalate by monosodium urate.
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What are 2 ways that magnesium prevents stone formation?
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1. Reduces ionic oxalate concentration by complexing with oxalate. 2. Reduces rate of calcium oxalate crystal growth.
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What is the most abundant protein found in urine?
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Tamms Horsfall protein
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How does Tamms Horsfall protein prevent stones?
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Potent inhibitor of calcium oxalate monohydrate crystal aggregation but NOT growth.
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What is the most potent stimulator for intestinal calcium absorption?
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Active Vitamin D (1,25 (OH)D)
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How does a decrease in serum calcium stimulate calcium absorption?
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This stimulates PTH secretion which directly stimulates 1alpha-hydroxylase and then 1, 25 OH Vitamin D binds to Vitamin D receptor which enhances calcium absorption
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What are the three types of hypercalciuria?
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1. Absorptive (Types 1 and 2) 2. Resorptive 3. Renal leak
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What are the differences in types 1 and 2 absorptive hypercalciuria?
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Type 1 is when hypercalciuria is still high despite low calcium diet. Type 2 is when hypercalciuria goes away in a calcium reduced diet.
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What are three types of hyperoxaluria?
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1. Dietary (Vitamin C) 2. Enteric hyperoxaluria 3. Primary hyperoxaluria
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What enzyme is messed up in primary hyperoxaluria?
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AGT (alanineglyoxylate aminotransferase) - glyoxylate to glycine is prevented and glyoxylate --> oxalate
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How is primary hyperoxaluria inherited?
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AR
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What are the two types of primary hyperoxaluria?
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Type 1 is mutation in the AGT gene. Type 2 is a mutation of the glyoxylate reductase gene (less aggressive course)
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What is the treatment for primary hyperoxaluria?
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Combined liver-kidney transplant (ESRD by age 15). Kidney function remains stable after transplant.
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What are the main factors causing stones in chronic IBD?
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Dehydration, hypomagnesuria, hypocitraturia, hypokalemia, low urine pH
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What dietary substance increases urinary oxalate levels?
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Vitamin C
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How does uric acid cause stones?
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1. At pH < 5.5, uric acid crystallizes. 2. Uric acid increases urinary levels of monosodium urate which promotes calcium oxalate heterologous nucleation. 3. Uric acid crystals bind urinary GAGs like heparin that inhibit crystallization of calcium oxalate
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How does body pH determine citrate excretion?
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Metabolic acidosis reduces urinary citrate secondary to enhanced renal tubular reabsorption and decreased synthesis of citrate in peritubular cells
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What is "gouty diathesis"?
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Stone-forming propensity with low urine pH of unknown etiology
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What are the three types of RTA?
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Type 1 (distal), Type 2 (proximal), Type 4 (distal)
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What is Type 1 RTA?
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Distal RTA is the inability to acidify urine in presence of systemic acidosis. Hypokalemia, high urine pH >6.0, and nephrocalcinosis.
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What is the most common stone associated with distal (type 1) RTA?
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Calcium phosphate (from hypercalciuria, hypocitraturia, and increased urinary pH)
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What is Type 2 (Proximal) RTA?
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Defect in HCO3- reabsorption with initial high urine pH that normalizes as plasma HCO3- decreases and amount of filtered HCO3- falls
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What is Type 4 (Distal) RTA?
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Associated with chronic renal damage, hyperkalemia, hyperchloremic metabolic acidosis
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Which chromosomes are associated with cystine stone formation?
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Chromosomes 2 (Type A) and 19 (Type B) and Type AB, genes SLC3A1, SLC7A9
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Name urea-splitting bacteria.
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Proteus, H. influenzae, Bordetella pertussis, Bacteriodes, Yersinia, Brucella, Staph aureus, Corynebacterium, Cryptococcus, Candida, Sporobolomyces, Trichosporon, Rhodotorula, Occasionally Klebsiella, Serratia, Pseudomonas, Pasteurella, Staph epidermidis, Bacillus, Clostridium, Mycobacterium
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What is the most common organism associated with infection stones?
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Proteus
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Name the 4 most common species that are urease-producing?
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Proteus, Staph, Klebsiella, and Pseudomonas
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What predisposes to ammonium acid urate crystallization?
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Laxative abuse, recurrent UTIs, recurrent uric acid stone formation, and IBD
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How may thiazides cause stones?
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They cause intracellular acidosis and therefore hypocitraturia
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Why is the right ureter more affected in hydro of pregnancy?
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Due to the more engorged right uterine vein and derotation of the enlarged uterus
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How is diabetes related to uric acid stone formation?
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Diabetes and insulin resistance causes altered ammonium managmeent and acidic urine with predisposition to uric acid and calcium oxalate stones
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How much creatinine is expected in a normal 24-hour urine collection?
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Males = 15-20mg creatinine/kg. Females = 10-15 mg creatinine/ kg
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What blood tests are initially used to test stone-formers?
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SMA, PTH, Calcium, Uric Acid
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