Renal Calculi and Nephrocalcinosis Flashcards
Type and frequency of renal stones in the UK.
Calcium oxalate usually with calcium phosphate (65%)
Calcium phosphate alone (15%)
Magnesium ammonium phosphate aka Struvite (10-15%)
Uric acid (3-5%)
Cystine (1-2%)
Calcium oxalate and phosphate stones men vs women.
More common in men.
Mixed infective stones men vs women.
More common in women 2:1.
Causes of renal calculi.
Dehydration
Hypercalcaemia
Hypercalciuria
Hyperoxaluria
Hyperuricaemia and hyperuricosuria
Infection
Cystinuria
Primary renal disease
Drugs.
Give examples of impairment of inhibitors that prevent crystallisation.
Inorgnaic magnesium
Pyrophosphate
Citrate
Glycosaminoglycans
Nephrocalcin
Most common causes of hypercalciuria.
Hypercalcaemia
High dietary intake of calcium
Excessive resorption of calcium from the skeleton
Idiopathic
Some common causes of hypercalcaemia.
Primary
Vitamin D ingestion
Sarcoidosis
Genetic causes of hyperoxaluria.
Inborn errors of glyoxylate metabolism.
Alanine-glyoxylate aminotransferase deficiency
Glyoxylate reductase hydroxypyruvate reductase deficiency
Prognosis of genetic causes of hyperoxaluria.
Widespread calcium oxalate crystal deposition in the kidneys leading to CKD in late teens or early twenties.
Successful liver transplantation has been shown to cure the metabolic defect.
Common causes of mild hyperoxaluria.
Excess ingestion of spinach, rhubarb and tea.
Dietary calcium restriction leading to increased absorption of oxalate.
GI disease such as Crohn’s leading to increased absorption of oxalate.
Causes of hyperuricaemia.
Idiopathic gout
Myeloproliferative disorders leading to increased cell turnover.
Dehydration
Patients with ileostomies (loss of bicarb leading to acidic urine)
Causes of struvite stones.
UTI especially due to Proteus mirabilis which hydrolyse urea.
Primary renal diseases leading to calculi.
Polycystic renal disease
Medullary sponge kidney leading to dilation of the collecting ducts that leads to urinary stasis and calcification.
Renal tubular acidosis . Presistently alkaline urine and reduced urinary citrate excretion lead to stone formation.
Drugs that promote calcium stone formation.
Loop diuretics
Antacids
Glucocorticoids
Theophylline
Vitamins D and C
Acetazolamide
Drugs that promote uric acid stones.
Thiazides
Salicylates
Drugs that can precipitate into stones.
Indinavir
Trimaterene
Sulfadiazine
Clinical features of renal calculi.
Usually asymptomatic
Most common symptoms is pain.
Haematuria
UTI
UTO
Sweating, pallor, vomiting
Explain the pain in renal calculi.
Sharp or dull
Constant, intermittent or colicky
Fluids and diuretics can worsen it
Exertion might mobilise some calculi and cause pain
When a stone enters the ureter it will cause pain and associated nausea.
What are bladder stones associated with?
Bacteriruia
Frequency
Dysuria
Haematuria
Severe introital or perineal pain may occur if trigonitis is present.
Investigations of renal calculi.
FBC, U&Es, Ca2+, PO43-, glucose, bicarbn, urate
Urine dipstick usually +ve for blood
Urine pH
24h urine for calcium, oxalate, urate citrate, sodium, crea and stone biochemistry.
Mid-stream speciemn of urine
Ultrasonography
Non-contrast CT (CT-KUB) is the best investigation of choice. It helps exclude other differentials such as rupture AAA. 99% of stones are visible.
XR-KUB 80% of stones are visible.
What stones are radiolucent?
Uric acid stones.
However with injection of contrast it shows as a filling defect.
It can also be seen on CT.
Management of calculi regardless of size.
Analgesia (diclofenac 75mg IV/IM or 100 mg PR), opioids if CI.
Antibiotics (piperacillin/tazobactam or gentamicin) if infection.
Lots of fluids!
Management of stone < 5 mm in lower ureter.
90-95% pass spontaneously.
Just increase fluid intake.
Management of stone > 5 mm/pain not resolving.
Start nifedipine 10mg/8h or alphablockers like tamsulosin.
If it still doesn’t pass try ESWL if the stone is less than 1 cm or ureteroscopy using a basket.
Percutaneous nephrolithotomy can be used to remove larger stones, mutliple or complex.
Prevention of urinary calculi.
Drink plenty
Normal dietary Ca2+ intake (not too low as that can cause refractory Oxalate excretion and oxalate stone)
In calcium stones a thiazide can be used.
In oxalate stones pyridoxine can be used and reduced oxalate intake.
In struvite stones you treat infection promptly or might even need proactive antibiotics.
In urate stones allopurinol, urine alkalinisation can also help.
Cystine requires vigorous hydration.
Give causes of nephrocalcinosis.
Renal cortical necrosis (rare)
Hypercalcaemia
Renal tubular acidosis
Primary hyperoxaluria
Medullary sponge kidney
TB
