Nephrolithiasis Flashcards
What is Nephrolithiasis?
Nephrolithiasis specifically refers to calculi in the kidneys, The majority of renal calculi contain calcium. The pain generated by renal colic is primarily caused by dilation, stretching, and spasm because of the acute ureteral obstruction.
What are the classic urinary tract symptoms of Nephrolithiasis?
- Pain
- classic colicky “loin to groin pain or renal pain”
- gross or microscopic Haematuria
- Dysuria and strangury
What are the systemic symptoms of Nephrolithiasis?
- Restless patient often writhing in distress
- Nausea, vomiting, or both (shared innervation between renal capsule and intestines)
- Fever and Chills (if associated with infection)
Which gender is most likely to suffer with kidney stones?
Men 2X more than women.
During what season is the incidence of kidney stones greater and why?
Summer/dehydration or insufficient fluid intake
Which stones are the most hazardous?
Because they pass into the ureters, producing pain referred to as colic as well as ureteral obstruction
What are the 3 most likely points of kidney stone impaction?
- Ureteropelvic Junction
- Crossing of the Illiac vessels
- Entrance to the bladder
What is the supportive test for kidney stone?
Urine analysis
- Hypercalciuria in the absence of hypercalcemia
- Crystals in the urine are also supportive of a diagnosis of kidney stones
What is another diagnostic tool for kidney stones?
A KUB
What is a KUB?
A plain film radiograph focused on kidneys ureter and bladder.
What type of kidney stones would NOT show up on KUB?
Uric acid stones; are Radio lucent.
What is the best diagnostic tool for kidney stones?
Unenhanced spiral (helical) CT
What would you use ultrasound to diagnose in terms of Nephrolithiasis?
Hydronephrosis
What drug is known to cause kidney stones?
Idinovir - Protease inhibitor
What kind of stone does Idinovir cause?
Radiolucent stones
What is the most common type of stone?
Calcium oxalate usually with calcium phosphate.
What are the remain stones and their frequencies?
- Calcium Phosphate
- Magnesium ammonium phosphate (struvite)
- Uric Acid
- Cystine
What is the most common metabolic abnormality causing calcium stones?
Hypercalciuria
What are other factors important in stone formation?
- Decreased urine volume (conc the urine)
- Reduced urine citrate (citrate chelates Ca2+)
- Primary HPTH
- Diets high in diary products
- Urinary infections due to urease producers (Proteus)
In what sub populations would one expect to see an increased incidence of Calcium stones?
1.Pure Vegans and those with Crohn’s disease
What type of stones are most common in children?
Calcium Phosphate
What are calcium phosphate stones associated with?
- Diary products
2. Distal renal tubular acidosis
What are Staghorn calculus or Struvite stones made of?
MAP Magnesium ammonium phosphate
What are MAP stones associated with?
- Urease producers such as proteus
2. Very alkaline urine which smells like Ammonia
What size stone is most likely to be spontaneously passed?
<5mm
What size stones are unlikely to pass?
between 5->7mm
What medications increase the chances of passing stones?
- Alpha 1 adrenergic antagonists
2. Calcium channel blockers
What are the common complications of kidney stones?
1.Obstruction
2.Infections
1+2=Medical emergency
What are the determinants of crystallization of stones?
- Supersaturation
- Concentration of solute
- Solubility of Solute
- pH 5.Inhibitors i.e citrate
- Nidus: another crystal from nanobacteria
What is the most common metabolic reason for hypercalciuria?
Increased absorption
What are the specific risk factors for Calcium Oxalate stones.
- Hypercalciuria
- Hyperoxaluria
- pH Alkaline Urine
- Insufficient Urinary citrate stemming from Systemic acidosis
- Uric Acid / Gout
What are the metabolic risks factors for Calcareous stones?
- Hypercalciuria
- Hyperuricosuria
- Hyperoxaluria
- Hypocitriuria
- Other (Vitamin A deficiency, hot climates, immobilization, urinary tract anomalies)
What are the Bacteria responsible for Struvite stones?
- Proteus
- Serratia
- Klebsilla
- Mycoplasma
What is the composition of Struvite stones?
Lamellated stones composed of layers of Bacterial products and mineral
How would you get rid of Struvite stones?
- Physical removal
- Antibiotics against causative agents
- Acetohydroxamic acid a urease inhibitor but its rarely used
What are the Risk factor for Uric acid stones?
- Hypercosuria
- gout
- dietary purine intake (animal protein) Tumor lysis
- Acidic urine
Why do animal proteins more likely cause stones than plant proteins?
Sulhydryl groups
What are the causes of Cystine stones?
- Cystine poorly soluble
2. Cystinuria due to rare autosomal recessive disorder of dicarboxylic acid transport
How can one increase the solubility of cystine in urine?
- Solubility increases with Alkaline urine pH
2. Penicillamine increase solubility but poor side effect profile
What are a few drugs known to cause stones?
- Triamtere
- Protease inhibitors (Indinavir;atazanavir)
- Guaifenesin
- Silicate (overuse of antacids containing magnesium silicate)
- Sulfa drugs
What is the standard treatment for Calcium stones?
1.Hydrochlorothiazide
-increases renal tubule absorption of Ca2+
2.Cellulose Phosphate
Binds calcium in the intestine
What is the single most important factor to correct as to avoid recurrence of Kidney stones?
Low urine volume. MUST INCREASE URINE OUTPUT TO ABOUT 2 LITRES A DAY
What are treatments for Uric Acid stones?
- Allopurinol
2. Increase urinary pH (make alkaline)
What do you not advice patients with calcium stones to do?
Reduce calcium intake
-Calcium intake must remain normal
What are some recommendatio to reduce risk of recurrent stones?
- Increase fluid intake
- Decrease animal protein intake
- Reduce dietary salt intake
- Decrease dietary oxalate (Chocolate, nuts,etc)
- Cranberry juice decreases oxalate and phosphate excretion
