Renal: Renal Colic Flashcards
What is renal colic?
Describes an intense wave-like pain related to the passage of ureteric stones.
Are renal stones more common in males or females?
Males 3x
When do renal stones cause pain?
Renal calculi do not ordinarily cause pain when they remain in the kidney. However, when those kidney stones drop into the ureters, it can be excruciating.
What are the 2 key complications of renal stones?
1) Obstruction: leading to AKI
2) Infection: with obstructive pyelonephritis
How can obstruction of a ureter be fatal?
The stasis of urine in a blocked kidney can lead to superimposed infection, which can cause rapid-onset sepsis.
What are the 3 anatomical points that renal calculi often obstruct the ureters?
1) Pelvic ureteric junction (PUJ): the junction between the renal pelvis and ureter
2) Pelvic brim: where the ureter crosses above the common iliac vessels into the pelvis
3) Vesicoureteric junction (VUJ): the junction between the ureter and bladder
What causes the colicky pain in ureteric calculi?
This is from reflex spasms of the ureter as the stone passes through.
Anatomically, what nerve does the ureter lie close to?
Genitofemoral nerve (a branch of the lumbar plexus)
What referred pain may be seen in renal stones in men?
Referred testicular pain (hence the characteristic description of ‘loin to groin’ pain) –> due to the ureter lying close to the genitofemoral nerve.
Broad risk factors for the formation of kidney stones?
1) Dehydration
2) Previous stones or FH
3) Metabolic conditions (e.g. cystinuria, primary hyperparathyroidism, gout etc.)
4) Medications including diuretics, antiretrovirals and antacids predispose to stone formation
5) Obesity
6) Bowel conditions (e.g. inflammatory bowel disease)
7) Idiopathic (most stones)
What are the 5 different types of kidney stones?
1) Calcium oxalate
2) Calcium phosphate
Note - calcium stones may be mixed (oxalate & phosphate).
3) Uric acid
4) Struvite
5) Cystine
What is the most common type of kidney stone?
Calcium oxalate
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
Hyperoxaluria can increase the risk of calcium oxalate stones.
What is hyperoxaluria? Causes?
A state of disordered metabolism characterised by an increased urinary excretion of oxalate.
Causes:
- genetic defect
- eating too many foods high in oxalate e.g. green leafy veg, soy etc
What foods are high in oxalate?
Green leafy veg, soy, almonds, potatoes etc
Why is hypocitraturia a risk factor for calcium oxalate stones?
Because citrate forms complexes with calcium, making it more soluble.
Appearance of calcium oxalate stones on xray?
Radio-opaque (though less than calcium phosphate stones)
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.
Appearance of cystine stones on xray?
Relatively radiodense because they contain sulphur
What is uric acid a product of?
Purine metabolism
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
Appearance of uric acid stones on xray?
Not visible on xray - radiolucent.
Risk factors for calcium phosphate stones?
1) May occur in renal tubular acidosis –> high urinary pH increases supersaturation of urine with calcium and phosphate
2) Renal tubular acidosis types 1 and 3 increase risk of stone formation (types 2 and 4 do not)
Appearance of calcium phosphate stones on xray?
Radio-opaque
What are struvite stones formed from?
Magnesium, ammonium and phosphate
What do struvite stones occur as a result of?
Urease producing bacteria
What are struvite stones associated with?
Chronic infections
What is typical urine pH?
individual variation from pH 5-7
How does eating affect urine pH? Why?
Post prandially the pH falls as purine metabolism will produce uric acid.
When a renal stone is not available for analysis, what may help to determine which stone was present?
Urine pH
Describe typical urine acidity in calcium phosphate stones
Normal- alkaline (pH >5.5)
Describe typical urine acidity in calcium oxalate stones
Variable (typically around 6)
Describe typical urine acidity in uric acid stones
Acidic (5.5.)
Describe typical urine acidity in struvate stones
Alkaline (>7.2)
Describe typical urine acidity in cystine stones
Normal (around 6.5)
Clinical features of renal colic?
Symptoms:
- sudden onset, severe unilateral loin-groin pain (‘worse than childbirth’)
- nausea & vomiting
- pain on urination (dysuria)
- systemic symptoms (e.g. fever): suggests an infected, obstructed system
- hypercalcaemia symptoms
Signs:
- typically unremarkable abdominal examination.
- severe, unilateral flank pain on palpation can indicate an infected urinary system.
- haematuria
- reduced urine output
Describe the pain in renal colid
Typically severe, intermittent, sharp ‘colic’ pain.
The patient often is restless/moving around.
Pain will wake patients up from sleep.
How long can episodes of colicky pain last in renal colic?
Can vary substantially in their duration, from seconds to hours. For patients with an infected, obstructed system, the pain can be constant.
Important areas to cover in history in renal colic?
1) PMH:
- previous stones
- metabolic conditions (cystinuria, primary hyperparathyroidism, gout etc)
2) DH:
- diuretics
- antiretrovirals
- antacids
3) FH
4) SH:
- smoking (a risk factor for stone formation)
- fluid intake
- occupation (heavy machinery operators or pilots will not be able to work until the stone is treated)
Which medications may increase the risk of renal stones?
1) aspirin
2) antacids
3) diuretics
4) antiretrovirals
5) Abx e.g. ciprofloxacin