Kidney Stones Flashcards
What is urolithiasis?
Formation of stones in the urinary tract
What is the commonest site of renal stone formation?
Renal pelvis
What percentage of kidney stones occur as unilateral?
80%
How can bladder stones form?
Can descend from the kidneys
Can form in the bladder
Give some dietary conditions that increase a patient’s risk of kidney stones
Low protein diet Chronic diarrhoea Dehydration Increase oxalate consumption Vitamin A, B1, B6 deficiencies Magnesium deficiency
What is a lithotomy?
Surgical removal of a calculus
From bladder, kidney or urinary tract
What are the complications of kidney stones?
Haemorrhage Infection Fistulae Incontinence Erectile dysfunction
Is it easier for men or women to pass stones?
Women
Have a shorter urethra
Name some causes of bladder stones
Bladder outflow obstruction (stricture, BPH)
Presence of a foreign body
Some are passed down from upper urinary tract
What are 2 other names of a kidney stone?
Renal calculus
Nephrolith
Are stones more common in men or women?
Men (2:1)
Which kidney stones are the only type commoner in women?
Struvite stones
What percentage of kidney stones are a type of calcium stone?
99%
Name the different types of calcium stones starting from the most prevalent
Calcium oxalate (with calcium phosphate)
Calcium phosphate
Struvite (infection)
Uric acid
Name some kidney stones that are not calcium based
Cysteine stones
Drug stones
Ammonium and urate stones
Urine stones
When do urine stones form?
When there is a supersaturation of the urine with minerals
Minerals start to crystallise out of solution
What pathologies can lead to increased mineral content in the urine?
Hypercalcaemia -> hypercalciuria
Hyperoxaluria
Hyperuricaemia -> hyperuricosuria
Cysteinuria
Acidic urine favours the formation of which stones?
Calcium oxalate
Uric acid
Alkaline urine favours the formation of which stones?
Calcium phosphate
How do the majority of calcium oxalate stones seem to form?
Appear to grow like stalactites
Attached to exposed interstitial deposits of calcium phosphate
(Randall’s plaque)
Core of calcium phosphate surrounded by calcium oxalate
55% of calcium oxalate stones are associated with which plasma/urine abnormalities?
Hypercalcuria
Without hypercalcaemia
Name the 3 substances that control calcium levels
PTH
Calcitriol (activated vit D)
Calcitonin
In which organs are the most calcium sensing receptors located?
Parathyroid glands
Kidney
Brain
Describe the effects of PTH
Increased osteoclastic resorption of bone Increased intestinal absorption Increased synthesis of calcitriol Increased tubular reabsorption Increased excretion of phosphate
Describe the effects of calcitriol
Increased calcium absorption in gut
Increased calcification and resorption of bone - keeps bone turning over
Describe the effects of calcitonin
Inhibits osteoclastic resorption of bone
Increased renal excretion of calcium and phosphate
What is the most common metabolic abnormality in calcium stone formers?
Hypercalcuria
Name some causes of hypercalcuria
Idiopathic
Hypercalcaemia
Increased dietary intake of calcium
Excessive resorption of calcium from skeleton
Name some causes of hypercalcaemia
Hypersecretion of PTH
Destruction of bone tissue
Excessive vit D ingestion
Thiazides
Describe primary hypersecretion of PTH
Parathyroid hyperplasia
Tumour
Name some reasons for destruction of bone tissue
Primary tumour of bone marrow
Diffuse skeletal metastases
Paget’s disease of bone
Immobilisation
Give some clinical signs of hypercalcaemia
Severe muscle weakness
Painful bones
Renal stones
Abdominal groans - constipation, ulcers, gallstones etc
Psychic moans - depression, lethargy, seizures
Give some causes of hyperoxaluria
Rare autosomal recessive genetic disorder of oxalate synthesis
Increased intestinal absorption of oxalate
High oxalate diet
Low calcium intake
Describe struvite stones
More common in women
Mixed infective stones
Composed of magnesium ammonium phosphate
Usually secondary to infection of organisms with urease
Often large
Why are uric acid stones difficult to diagnose?
Radiolucent
Cannot see them on an xray
Uric acid is the end point of which molecule metabolism?
Purine
Give some causes of hyperuricaemia
Gout
Secondary consequence of increased cell turnover (malignancy, chemotherapy)
Describe the presentation of kidney stones
Asymptomatic (most) Renal colic Dull ache in loins Recurrent UTIs Haematuria Renal failure UT obstruction
Why does drinking water often make the pain in real stones worse?
Fluid is increased in kidneys
Increased pressure on stones
What is renal colic?
Excruciating pain
Bouts of 20-60 minutes
Peristaltic contractions/spasms
Loin to groin pain
What symptoms often accompany renal colic?
Nausea/vomiting Pallor Sweating Restlessness (Haematuria)
What investigations would you do for renal stones?
Mid stream urine: blood, culture etc
Serum: urea, creatinine, electrolytes, calcium
Plain abdominal x-ray (can see 60% of stones)
CT of kidneys, ureter and bladder
Stones under which diameter are usually passed?
< 5mm
What are some severe complications of renal stones?
Acute pyelonephritis Pressure necrosis of renal parenchyma Urinary obstruction Hydronephrosis Ulceration
Describe the treatment of urinary stones
Analgesia, warmth to site and bed rest
Ureteroscopy
Percutaneous nephrolithotomy
ESWL (extracorporeal shock wave lithotripsy)
