13. Urinary Calculus Disease Flashcards
What different types of stones exist in the context of Urinary Calculus Diseases?
- Calcium Oxalate
- Urate
- Magnesium Ammonium Phosphate
- Cysteine
- Xanthine, Idinavir, Matrix
What is generally the most common composition of kidney stones?
80% CaOX
20% CaPO4
What are the main properties of the Calcium Oxalate stone?
- Most common type of stone
- Insoluble
- Shows up on X-rays
What conditions are associated with the Calcium phosphate stone?
- Hyperparathyroidism
- Distal Renal Tubular Acidosis (Type 1)
- Medullary Sponge Kidney (MSK)
- Urinary Stasis and infection
What diseases can Urate crystals associate with?
- Metabolic Syndrome
2. Gout
Which stones can be seen well on X-rays?
- Calcium Oxalate
- Calcium Phosphate (reasonably well)
- Magnesium Ammonium Phosphate (slightly)
- Cysteine (POOR)
How hard is Magnesium Ammonium Phosphate stones?
200-600 HU (soft)
What are Magnesium ammonium phosphate crystals usually called?
Struvite
Which stones are associated with Staghorn Calculi?
Magnesium Ammonium Phosphate
Which stones are associated with metabolic syndrome?
Urate
Which stones are associated with cysteinuria
Cysteine
What stones make white smomke and a rotten egg smell during lasering?
Cysteine (H2S)
What type of stone used to show up poorly on CT and was initially used for HIV?
Idinavir
What are the Two Factors influencing Stone formation?
Free
Fixed
What is the Free Theory influencing Stone Formation?
Presence of Stone Constituents in appropriate amounts (without inhibitors) WILL form stones
What is the Fixed Theory influencing Stone Formation?
Energy needed to make a crystal (Lattice Enthalpy of Formation) is Lower if there is a surface to form them on
What is the Free Theory affected by?
- Solute Concentration
- Urine Acidity
- Formation Inhibitors
What is the Fixed Theory affected by?
- Surface the lattice forms on
- The Crystals
- Randall’s Plaques
How do Calcium Oxalate stones form?
- Randall’s Plaques
- CaPhos forming in the kidney interstitium
- Urothelium ulcerates and exposes plaque to urinary surface - Duct of Bellini Plugs
- Stones form in the tubes and get stuck on the papillary surface
How do we get excessive Calcium in our systems?
Hypercalcemia
- Hyperparathyroidism
- Sarcoidosis
- Excess Vitamin D
How do we get excessive Oxalate in our systems?
- Diet
- Endogenous sources from liver (Glycolate metabolism)
- Vitamin C conversion too
How does Calcium oxalate form?
Calcium binds to oxalate in the gut and stops it from being absorbed
What can cause Enteric Hyperoxaluria?
Malabsorption
- Colitis (Crohn’s)
- Jejunoileal Bypass surgery
What foods have High levels of unopposed oxalate
- Beetroot
- Spinach
- Rhubarb
What is THP?
Tamm Horsfall Protein/Uromodulin
What does THP do?
Inhibits stone formation
How does THP work?
Prevents stones from binding to renal epithelial cells and reduces free calcium on the crystal for growth
Mutations on THP can often lead to what?
- Familial Juvenile Hyperuremic Nephropathy
2. Medullary Cystic Kidney Disease 2
A man presents with sudden onset of
- Severe RHS Loin Pain + Tenderness
- Pain radiates to Groin
- Writhing in Agony
- Apyrexia
- Blood ++ on Urine
- FBC Normal
- Elevated Creatinine
What is the likely cause of pain?
Ureteric Colic: Comes and goes with background of pain
Differentials
- Bowel Colic comes and goes completely between bouts
- Leaking AAA must be considered in older
- Biliary Colic: Right Upper Quadrant
- Ectopic Pregnancy
- Pneumonia/Pancreatitis/MI
- Pyelonephritis
- Bleeding Tumours (Renal Cell Carcinoma)
For Ureteric Colic, you must be mindful of Infection. What tests should be done?
- Urine Dip
- Leukocytes/Nitrates/Urine pH - MSU
- Blood Tests
- FBC
- U+E (Creatinine, but beware of a stone in a solitary kidney)
- Calcium and Urate
What is the mainstay of Imaging stones in kidneys?
Ultra Low Dose CTKUB
- 99% diagnosed
What alternatives are there for Kidney imaging
- Ultrasound
- Non-irradiating
- Best for Pregnancy and children
What is the Sensitivity and Specificity of CTKUB?
50%
- Urate stones tend to be lucent
What is the sensitivity of US for kidney stones?
75%
- Can miss big and small ones
What treatment can be provided for Kidney Stones?
- Analgesia
- Hydration
- Medical Expulsive Therapy
- Removal of stone
What can be provided Analgesia-wise for kidney stones?
NSAIDs
Opiates
How can hydration be provided for kidney stones?
IV if necessary especially if they are vomiting
How is Medical Expulsive Therapy performed for kidney stones?
Tamsulosin relaxes the lower ureter and increases the stone passage
Why can’t we use Medical Expulsive Therapy for the Upper Ureter?
Few alpha receptors are here
When indications can Metabolic Testing be used for Kidney stones?
- Multiple stone attacks
- Bilateral stone disease
- Solitary kidney
- Urate/Cysteine/Calcium stones
What does Metabolic Testing involve?
- 2 x 24 hour urine collections: Calcium/Oxalate/Urate/Volume/Sodium and Citrate
- Spot Nitroprusside test for Cysteine
- Blood tests: Calcium, Urate, Bicarb, U&Es
What is the best way of preventing Kidney stones?
- Increase Urine Flow >2L per day
- Reduce Sodium and Increase Potassium (Citrus)
- Low oxalate
- Low fats
- High protein
What are the best drug therapies for kidney stone prevention and why?
- Thiazides (Reduces Calcuria)
- Potassium Citrate (Poor toleration)
- Sodium Bicarbonate
- Allopurinol
- Penicillamine and Thiola (Cysteinuria)
How can we monitor the treatment of Kidney stones?
- 24 Hour Urine
- Urine volume and Na intake - Spot urine for Na/K as an alternative
- Blood urate in Allopurinol users
- Help from an endocrinologist in Metabolic Syndrome
When is the next follow up expected for an individual with Kidney stones?
- 50% chance of another stone in 10 years if there is no change in diet
- Increasing Fluid Intake will reduce risk by 40%
- 6-12 month KUB is good
