Revision - Renal Stones & Renal Flashcards
What are 2 key complications of renal stones?
1) Infection –> pyelonephritis
2) AKI due to obstruction
Anatomically, what nerve does the ureter lie close to?
Genitofemoral nerve
This causes ‘loin to groin’ pain (i.e. referred testicular pain in men).
What are the 5 different types of kidney stoines?
1) Calcium oxalate (most common)
2) Calcium phosphate
3) Cystine
4) Struvite
5) Uric acid
What is the major risk factor for calcium oxalate stones?
Hypercalciuria
Causes of hypercalciuria?
Note - any cause of hypercalcemia is likely to result in secondary hypercalciuria.
1) Hyperthyroidism
2) Renal tubular acidosis
3) Sarcoidosis
4) Vitamin D intoxication
5) Glucocorticoid excess
6) Paget disease
7) Paraneoplastic syndromes e.g. lung squamous cell carcinoma
Why is hypocitraturia a risk factor for calcium oxalate stones?
Because citrate forms complexes with calcium, making it more soluble.
What is the key risk factor for cystine stones?
Cystinuria –> Inherited recessive disorder of transmembrane cystine transport leading to DECREASED ABSORPTION of cystine from intestine and renal tubule.
Risk factors for uric acid stones?
1) low urinary pH
2) high protein diet
3) loss of fluid due to chronic diarrhea or malabsorption
4) diabetes or metabolic syndrome
Which type of kidney stones are not visible on xray?
Uric acid stones (radiolucent)
What are struvite stones formed from?
Magnesium, phosphate & ammonium
What do struvite stones occur as a result of?
Urease producing bacteria
They are associated with chronic infections
What is typical urine pH?
Variation from 5-7
pH of urine after eating?
Post-prandial drop in pH due to purine metabolism producing uric acid
Describe typical urine acidity in uric acid stones
Acidic (around 5)
Describe typical urine acidity in struvate stones
Alkaline (>7)
Which diuretics can cause renal stones?
Loop diuretics –> cause urinary excretion of calcium
Do thiazide diuretics cause renal stones?
No - they do not cause urinary excretion of calcium
Which medications may increase the risk of renal stones?
1) aspirin
2) antacids
3) diuretics
4) antiretrovirals
5) Abx e.g. ciprofloxacin
What is the most important differential for renal colic?
Ruptured AAA
Always consider in older men w/ risk factors
Presentation of portal vein thrombosis?
Severe RUQ pain, often with jaundice
What is there often a preceding history of in diverticulitis?
Constipation
Gold standard imaging in renal stones?
Non-contrast CT KUB
When may an US be indicated over a CT KUB?
In younger or pregnant patients
What is the most effective analgesia for renal colic?
NSAIDs
Typical NSAID used in renal colic?
IM diclofenac
What size renal stone may indicate a ‘watching and waiting’ approach’?
<5mm
review again in 4 weeks