Kidney Stones - NACE Flashcards
What is the lifetime risk of getting a kidney stone?
10% of people will get a kidney stone in their lifetime
T or F: by the age of 70 women are twice as likely as men to get a kidney stone.
False, women are HALF as likely as men to get kidney stones
After getting a kidney stone, what is the recurrence risk of it coming back?
- 5% per year recurrence risk (1/20 ppl who have had a kidney stone will get another one within the next year)
- This is a high rate of Recurrence
What factors effect the concentration of solutes that may precipitate in the urine causing stones?
Amt of Solute:
• Filtered Load
• Tubular Secretion
• Tubular Reabsorption
Vol. of Solvent:
• Salt and Water Balance
What are the 4 types of solute that account for the majority of stones?
- Calcium Salts (75%)
- Stuvite (15%)
- Uric Acid (10%)
- Cysteine
What causes Cystinuria?
• how common is this?
• Epidemiology?
• Why must we catch this?
Cystinuria = GENETIC disorder of reabsorption in the Tubules
How Common/Epidemiology?
• Found in 1-2% of ADULT stones
• 5% of stones in CHILDREN
Why worry?
• Can cause LOSS of kidney function if left untreated
T or F: urine pH can provide a major clue to the type of stone that is likely to form in someone’s urine
True, pH is a MAJOR TARGET for INTERVENTIONS to prevent recurrent stones
Why are natural inhibitors so important?
Because the urine is typically supersaturated with solutes that comprise stones
Where is Tamm-Horsfall mucoprotein located and what would happen if you inhibited its formation?
Tamm-Horsfall is made in the THICK ASCENDING LOOP OF HENLE.
• it BINDS solutes, so preventing its formation would LEAD SO STONE FORMATION
T or F: presence of a foreign body in the kidney of ANY type will increase the propensity to form stones.
TRUE, calcium stone may from around Uric Acid or even Nanobacteria
*This is just seeding a cystalization
What is the utility of looking at crystals in the urine of a normal person?
• what about someone with a stone?
- NO utility in looking at stones in a normal person who doesn’t have stone
- IN someone WITH a stone, the crystals in the urine may tell you about COMPOSITION of the stone
Where are stones most likely to form?
• why is this?
Stones = most likely to form in the LOW URINE FLOW areas
- CALYCES and PELVIS are therefore the most common places to see stone formation
- stasis and stone formation is also the reason you can see bladder stones
T or F: stones are more likely to form in areas of obstruction.
True
What are the 2 subtypes of Calcium stones formed?
• which is more common?
• How does urine pH affect each of these?
2 types:
• Calcium Oxalate (60%) - INDEPENEDENT of pH
• Calcium Phosphate (15%) - FORMS STONES IN ALKALINE ENVIRONMENT
What are some drugs known to cause kidney stones?
- Indinavir
- Triamterene
- Acyclovir
- Sulfadiazine
Explain the ways that Ca2+ may increase in concentration leading to stone formation?
Increased Filtered Load:
=> Exogenous - inc. intake
=> Endogenous - inc. PTH, Vit. D. Sarcoid, Ideopathic
Decreased Renal Reabsorption:
• EXCESS DIETARY Na+
• Pharmacologic => LOOP diuretics
Decreased Urine Volume
Besides Ca2+, the concentration of what other substance is important to the formation of Ca2+ stones?
Oxalate, remember this forms stones indepedently of pH
Oxalate
• how is its concentration increased?
INCREASE filtered Load (ONLY): Exogenous: • Dietary XS • Low Ca2+ diet • bowel pathology
Endogenous:
• Increased Production
How can you treat Calcium Oxalate Crystals that are caused by too much Ca2+?
Reduce Ca2+:
• avoid Ca2+ supplement BUT DO NOT RESTRICT DIETARY Ca2+
• Potassium Citrate +/- allopurinol
Reduce Na+:
• THIAZIDE DIURETICS
• SODIUM RESTICTION
Dilute:
• Adequate Fluids
• Less Animal Protein, and Salt
also look for any underlying causes of hypercalcemia
What type of stones do you have a fairly high risk of getting with type I RTA?
• CaP, because this type of RTA PREVENTS ACIDIFICATION in the DISTAL TUBULE
= More Basic Environment and Decreases Citrate concentration
What is the more common cause of Uric Acid Kidney Stone formation: underexcretion or overproduction?
• exceptions?
Underexcretion = most common cause
• Ppl. with GOUT tend to OVERPRODUCE uric acid so both factors contribute to stone formation
Contrast the formation of CaP, Uric Acid, and Struvite stones.
CaP stones - form in a BASIC environment
Stuvite stones - form in a BASIC environment
Cysteine Stone - from in ACIDIC environment
Uric Acid stones - form in ACIDIC environment
What recommendations and prescriptions should be written to prevent Uric Acid crystal formation in patients.
Dietary Modifications:
• Increase Fluids
• Less Animal Protein
• Less EtOH
Drug Treatments:
• Allopurinol
• Potassium Citrate
When is the ONLY time you see Stuvite Stones forming?
- Presence of Increased Urinary NH4+ concentration and Alkaline pH
- this ONLY occurs with UTI with urease-producing organism (proteus, Serratia, Klebsiella, Mycoplasma)
What reaction is catalyzed by Urease?
• what common bacteria cause UTIs and carry urease?
• what is unique about the urine in this scenario?
Rxn:
• Urea => 2NH3 + CO2, NH3 takes a proton and becomes NH4+
Bugs: • Proteus • Serratia • Klebsiela • Mycoplasma
UNIQUE URINE:
• Patients have BASIC urine with INCREASED NH4+ (this is the opposite of what happens in acidosis)
T or F: symptoms in people who get Struvite stones are more related to Infections than presence of stones.
TRUE
What Therapies are given to people with Struvite Stones?
ANTIBIOTICS
INCREASE FLUID INTAKE
• stone removal
Urease inhibitors are not a great idea - lots of side effects
What Therapeutic Agent is effect at treating Cystine, Calcium, and Uric Acid stones but not struvite stones?
Potassium Citrate
Where does the defect take place that leads to cystinuria?
• what therapies can we give these pts?
• PROXIMAL tubular reabsorption defect
Therapies:
• make urine basic
• PENICILLAMINE
• potassium citrate
T or F: Cystinuria should be suspected in children who present with kidney stones
True, most commonly they present around age 12
How much should you increase fluid consumption to prevent kidney stones?
• Increase Fluid Intake to greater than 2L per day
Hypercalciuria
• Lifestyle Modifications
• Pharmological Treatment
Lifesytle:
• Sodium Moderation (less than 200 mmol/L per day)
• Protein Moderation
Pharmological:
• Hydrochlorothiazide
• Indapamide + Potassium Alkali
HypOcitraturia
• Lifestyle Modifications
• Pharmological Treatment
Lifestyle:
• Protein Moderation
Pharomological:
• Potassium Citrate
Hyperoxaluria
• Lifestyle Modifications
• Pharmological Treatment
Lifestyle:
• Oxalate Restriction
• Avoidance of Ca2+ restriction
Pharmological:
• Pyridoxine for Pirmary Hyeroxaluria
Hyperuricosuria
• Lifestyle Modifications
• Pharmological Treatment
Lifestyle:
• Purine Restriction
Pharm:
• Allopurinol
Low Urinary pH
• Lifestyle Modifications
• Pharmological Treatment
Lifestyle:
• Protein Restriction
Pharm:
• Potassium Citrate
Cystinuria
• Lifestyle Modifications
• Pharmological Treatment
Lifestyle:
• High Fluid Intake (Greater than 3L per day)
Pharm:
• Potassium Citrate
• D-penicillamine
• Beta-mercaptopropionyl-glycine
UTI treamtent
Abx.
What makes patients who have kidney stones symptomatic?
• Patients become symptomatic when the stone Moves
**Where is the stone going to get caught?
- Angulations
- Urteropelvic Junction
- Iliac Vessel Crossing
- Bladder entry or Outlet
What should be in your differential of someone who has pain from kidney stone?
- Diverticulitis, Appendicitis, Hernia
- Acute Cholecystitis, Acute Appendicitis, Pyelonephritis
- AAA (BE SURE to exclude this one)
What are you looking for in Urinanalysis to confirm Kidney stone?
- Crystals
- Microscopic Hematuria
- Urine Concentration
- pH
- Evidence of Infection
T or F: you will get evidence about elevated Ca, Cysteine, etc from UA.
FALSE, these values come from 24 hour collection, NOT from UA
What stones are radiolucent (translucent on x-ray)?
Uric Acid Stones - all other stone types are radiopaque
What would be your 1st choice technique to look for a kidney stone?
• what would be the most sensitive?
Ultrasound would be 1st choice because of Low Radiation and Fair Accuracy
• Problem is you can’t see ureteral stones
Helical CT - most sensitive, but exposes the pt. to radiation
What are the size limitations on passage of kidney stones?
Less than 5mm will usually pass
Greater than 7mm probably won’t
What do you do if kidney stones don’t pass?
Can be fragmented using Lithotripsy
How should you control pain associated with kidney stones?
• what should you do if a patient brings you the stone back?
NSAIDs (they are safer than opiates)
Note: Try to control their vomitting and send them home with a strainer
SEND STONES OFF TO ANALYSIS ALWAYS
What is the most common metabolic abnormality in Calcium Stone formers?
• HypercalenURIA, not hypercalcemia
IMPORTANT How do you determine if a 24 hour urine collection is complete?
The AMOUNT of Creatinine
MALES:
• should excrete 10mg/lb of lean body wt. per day
FEMALES:
• excrete 15% less
What is the most common abnormality causing kidney stones?
LOW URINE VOLUME
ABSOLUTELY DO NOT LOWER DIETARY Ca2+ to Prevent CaOx stones why?
• You will just absorb more oxalate
Note: you can use allopuriol to treat b/c Urate typically goes with it
What is the best advice to give a patient so that they keep their urine diluted?
• Tell them to keep their urine looking clear
Where does dietary oxalate come from?
• Chocolate and Nuts
T or F: urine protein concentration determines stone risk.
FALSE, dietary protein determines this
