Renal Calculi Flashcards
What are two other terms for renal calculi?
Nephrolithiasis
Urothliasis
What are renal calculi?
They are stones which form in the renal tract
What are the two general causes of renal calculi?
When urine becomes concentrated, allowing minerals and salts to crystallise and stick together
When urine lacks substances that prevent these crystals from sticking together
How are renal calculi classified?
They are classified upon the minerals and salts they are formed of
Why is renal calculi classification important?
This classification is useful in determining the cause of the renal calculi, therefore enabling clinicians to identify how the patient can reduce the risk of reoccurrence
What are the five classifications of renal calculi?
Calcium Oxalate
Calcium Phosphate
Struvite Calculi
Uric Acid Calculi
Cystine Calculi
What is the most common classification of renal calculi? What is the percentage of cases?
Calcium oxalate (85%)
What are the two sources of calcium oxalate?
It is produced physiologically by the liver
It is absorbed from the diet
What are the eight risk factors of calcium oxalate renal calculi?
Hypercalcaemia
Hypercalciuria
Hyperoxaluria
Hypocitraturia
Hyperparathyroidism
Medullary Sponge Kidney
Adult Polycystic Kidney Disease
Drug Administration
Which four drugs are associated with calcium renal calculi?
Loop diuretics
Steroids
Acetazolamide
Theophylline
Which drug class prevent calcium renal calculi?
Thiazide diuretics
How is hypercitraturia associated with calcium oxalate renal calculi?
This is due citrate forming complexes with calcium making it more soluble
Are calcium oxalate renal calculi radio-opaque or radio-lucent? What does this mean?
Radio-opaque
This means that these calculi appear white on radiographs enabling monitoring of their movement throughout the renal tract.
What is the urine acidity and mean pH in calcium oxalate renal calculi?
Urine acidity = variable
Mean pH = >6
What is the shape of calcium oxalate calculi?
Envelope
What are the two sources of calcium phosphate?
It is produced physiologically by the liver
It is absorbed from the diet
What are the four risk factors associated with calcium phosphate renal calculi?
Renal Tubular Acidosis Type One
Renal Tubular Acidosis Type Three
Medullary Sponge Kidney
Drug Administration
Are calcium phosphate renal calculi radio-opaque or radio-lucent? What does this mean?
Radio-opaque
This means that these calculi appear white on radiographs enabling monitoring of their movement throughout the renal tract
Which renal calculi are more radio-opaque - calcium oxalate or calcium phosphate?
Calcium phosphate
What is the urine acidity and mean pH in calcium phosphate renal calculi?
Urine acidity = normal
Mean pH = 6.5
What is another term for struvite calculi?
Staghorn calculi
What is struvite calculi composed of?
Magnesium
Ammonium
Phosphate
Where do struvite calculi tend to form?
They involve the renal pelvis and extend into at least 2 calyces
What is struvite?
It is magnesium ammonium phosphate mineral produced by bacteria in the urinary tract under alkaline conditions
What is a risk factor of struvite calculi?
Urinary tract infections
Which two urinary tract infections are most commonly associated with struvite calculi?
Ureaplasma urealyticum
Proteus
Are struvite renal calculi radio-opaque or radio-lucent? What does this mean?
Radio-opaque
This means that these calculi appear white on radiographs enabling monitoring of their movement throughout the renal tract
What is the urine acidity and mean pH in struvite renal calculi?
Urine acidity = Alkaline
Mean pH = >7.2
How is uric acid produced?
Purine metabolism
What causes uric acid calculi formation?
They are calculi that form when the levels of uric acid in the urine are elevated, resulting in urine becoming acidic at a pH less than 5.5
What are the four risk factors of uric acid calculi?
Gout
Adult Polycystic Kidney Disease
Metabolism Deficiencies
Ileostomy
Which patient group tend to be affected by uric acid calculi?
Children
Are uric acid calculi radio-opaque or radio-lucent? What does this mean?
Radio-lucent
This means that these calculi appear black on radiographs and their movement throughout the renal tract cannot be monitored
What is the urine acidity and mean pH in uric acid renal calculi?
Urine acidity = Acidic
Mean pH = < 5.5
What is a risk factor of cystine calculi?
Cystinuria
What is cystinuria?
It is a recessive genetic disorder that results in dysfunction of the transmembrane cystine transporter leading to decreased absorption of cystine from the intestine and renal tubule
What is the urine acidity and mean pH in cystine renal calculi?
Urine acidity = Normal
Mean pH = 6.5
Are cystine calculi radio-opaque or radio-lucent? What does this mean?
Semi-opaque
This means that these calculi have a ground glass appearance on radiographs enabling monitoring of their movement throughout the renal tract
What are the five renal stone classifications which are radio-opaque?
Calcium Oxalate Calculi
Calcium Phosphate Calculi
Mixed Calcium Oxalate/Phosphate Calculi
Triple Phosphate Calculi
Cystine Calculi
What are the two renal stone classifications which are radio-lucent?
Urate Calculi
Xanthine Calculi
What are the six risk factors of renal calculi?
Male Gender
Middle Aged, 30 – 55 Years Old
Family History
Dehydration
High Sodium Diet
Metabolic Conditions
Which two metabolic conditions are associated with renal calculi?
Inflammatory bowel disease
Chronic diarrhoea
When do renal calculi become symptomatic?
When they move within the renal tract
What are the five clinical features associated with renal calculi?
Loin Pain
Nausea & Vomiting
Dysuria
Haematuria
Urinary Tract Infection Features
Describe the loin pain associated with renal calculi
It is characterised by severe, sharp pain in the upper lateral abdomen, back or groin
It tends to occur in waves, fluctuating in intensity
What is dysuria?
It is defined as painful urination
What six investigations are used to diagnose renal calculi?
Blood Tests
Urinalysis
X-Ray Scan
Ultrasound Scan
Non-Contrast CT KUB Scan
Chemical Analysis
What are the five blood tests used to diagnose renal calculi?
Increased WBC Levels
Increased Calcium Levels
Increased Parathyroid Hormone Levels
Increased Creatinine Levels
Increased Uric Acid
What are the six urinalysis results which indicate renal calculi?
Increased WBC Levels
Increased Calcium Levels
Increased Uric Acid Levels
Increased Oxalate Levels
Decreased Citrate Levels
Haematuria
What are the two features of renal calculi on an x-ray scan?
Radio-Opaque Mass
Radio-Lucent Mass
What is the first line investigation used to diagnose renal calculi?
Ultrasound scan
How is an ultrasound used to diagnose renal calculi?
It is used to diagnose and monitor the movement of radio-opaque renal calculi in the kidney
What are the two features of renal calculi on ultrasound scans?
Radio-Opaque Mass
Hydronephrosis
What is hydronephrosis?
It is defined as dilatation of the kidney
It is a clinical sign that it is not draining efficiently due to obstruction
Can renal calculi in ureters be detected on an ultrasound scan? Why?
No
This is due to the presence of other organs anteriorly
What is the gold standard investigation used to diagnose renal calculi?
Non-contrast CT KUB scan
When should CT KUB scans be conducted to investigate renal calculi?
It should be performed on all patients within 14 hours of admission
However, in cases where a patient has a fever, solitary kidney or when the diagnosis is unclear it should be conducted immediately
What are the two clinical features of renal calculi on a CT urogram scan?
Radio-Opaque Mass
Hydronephrosis
How is chemical analysis of renal calculi conducted?
It involves asking patients to urinate through a strainer to catch stones that they pass
When is conservative management of renal calculi recommended?
It is recommended in small renal calculi < 5mm
What are the two conservative management options of renal calculi?
Observation
Hydration
How long can it take small renal calculi to pass spontaneously?
Four weeks
What is the pharmacological management option of renal calculi?
NSAIDs
Name two NSAIDs used to manage renal calculi
Ibuprofen
Diclofenac
Which analgesia should be administered in cases where renal calculi patients require secondary care admission?
IM diclofenac
What are the three surgical management options of renal calculi?
Extracorporeal Shock Wave Lithotripsy (ESWL)
Percutaneous Nephrostomy
Percutaneous Nephrolithotomy/ Ureteroscopy
What is the first line surgical management option of renal calculi in calculi < 2cm, with no obstructive features?
Extracorporeal Shock Wave Lithotripsy (ESWL)
Why is ESWL contraindicated in renal calculi > 2mm?
This is due to the fact that these calculi will be broken down into several small pieces, which may cause obstruction
What is ESWL?
It involves the use of sound waves to create strong vibrations that break the renal calculi into tiny pieces that can be passed in the urine
Which calculi classification tend to be resistant to ESWL?
Struvite
When is percutaneous nephrolithotomy recommended?
It is used to manage large (>2cm), proximal renal calculi.
It should also be considered in complex renal calculi and struvite calculi
What is percutaneous nephrolithotomy?
It involves intracorporal lithotripsy through endoscopic access to the renal collecting system
The remaining stone fragments are then removed
When is percutaneous nephrostomy/ uteroscopy recommended to manage renal calculi?
It is recommended in when ESWL is contraindicated, such as pregnant patients or in cases with obstructive features (hydronephrosis)
What is the first line management option of renal calculi in pregnant women?
Ureteroscopy
What is ureteroscopy?
It involves the passage of an ureteroscope through the ureter and into the renal pelvis to enable placement of a stent in situ for a period of four weeks
In which three circumstances are renal calculi deemed as surgical emergencies?
Ureteric obstruction
Renal developmental abnormality
Previous renal transplant
How do we manage renal calculi that have resulted in ureteric obstruction?
Decompression with nephrostomy tube placement, insertion of ureteric catheters or ureteric stent placement
What are the three prophylactic management options of calcium renal calculi?
Hydration
Low Sodium Diet
Thiazide Diuretics
What are the two specific prophylactic management options of calcium oxalate renal calculi?
Cholestyramine
Pyridoxine
What are the two prophylactic management options of uric acid renal calculi?
Allopurinol
Oral Bicarbonate
