Nephrolithiasis
Renal Stones
Types
high urinary levels of above, poor urine volume, obstruction
Hypercalciuria (Ketogenic diet)
Hypooxyluria (fat malabsorption e.g. CF)
Hypocitruria (metabolic acidosis increased citrate resorption in PT: ketogenic diet, RTA (topiramate carbonic anhydrase inh)
Hyperuricosuria (high protein diet, ketogenic diet)
Cystinuria
Hypomagnesuria
Renal tubular acidosis
hyperparathyroidism
Hx
Pain (60%): usually ureteric, Loin to groin, may be isolated flank or abdominal
Haematuria (40%)
Dysuria / urgency (10%) if bladder / urethral
Nausea/Vomiting (10%)
Asymtomatic (20%) if calyx /pelvix non obstructive (more likely in younger)
Hx/FHx stones
Medications
UTIs
Ix
Urine MCS (as associated with urostasis and infection)
Urine Ca:Cr (mmol:mmol), or 24 hour urine calcium (>4mg/kg/24h)
Radioluc: Uric acid radiolucent
Metabolic
AXR Sens 60% (lucent, small and stones over bone missed, doesn't pick obstruction
US: Sensitivity 75%: picks up radiopaque and lucent stones but misses small stones (>5 mm), and papillary, calyceal stones, and ureteral stones. Also picks up obstruction
CT non contrast: (Sens 95%) most sensitive picks up stone >1mm, picks up obstruction
High oxalate
Dx imaging or passed stone
Rx
Mg prevents Ca Ox stones
Citrate inhibits Ca stones
Types
- Ca Oxylate (50%)
- fat malabsorption (fat binds Ca > less Ca for oxalate to bind > increased absorption)
- Ca Phosphate (25%)
- Struvite (13%)
- UTIs > ammonia > ammonium > MgAmmoniumPO4 (struvite)
- Urease producing UTIs: Proteus, Providencia, Klebsiella, Pseudomonas, and enterococci
- UTIs > ammonia > ammonium > MgAmmoniumPO4 (struvite)
- Cystine (5%): AT disorder of amino acid absorption
- Uric acid (4%) RADIOLUCENT
- Mixed/other (4%)
high urinary levels of above, poor urine volume, obstruction
- Ca follows Na - high Na diet = hypercalciuria
Hypercalciuria (Ketogenic diet)
Hypooxyluria (fat malabsorption e.g. CF)
Hypocitruria (metabolic acidosis increased citrate resorption in PT: ketogenic diet, RTA (topiramate carbonic anhydrase inh)
Hyperuricosuria (high protein diet, ketogenic diet)
Cystinuria
Hypomagnesuria
Renal tubular acidosis
hyperparathyroidism
Hx
Pain (60%): usually ureteric, Loin to groin, may be isolated flank or abdominal
Haematuria (40%)
Dysuria / urgency (10%) if bladder / urethral
Nausea/Vomiting (10%)
Asymtomatic (20%) if calyx /pelvix non obstructive (more likely in younger)
Hx/FHx stones
Medications
UTIs
Ix
Urine MCS (as associated with urostasis and infection)
Urine Ca:Cr (mmol:mmol), or 24 hour urine calcium (>4mg/kg/24h)
- <6mo: <2.25 mmol/mmol
- 6-12mo: <1.7 mmol/mmol
- >2y: <0.6 mmol/mmol
Radioluc: Uric acid radiolucent
Metabolic
AXR Sens 60% (lucent, small and stones over bone missed, doesn't pick obstruction
US: Sensitivity 75%: picks up radiopaque and lucent stones but misses small stones (>5 mm), and papillary, calyceal stones, and ureteral stones. Also picks up obstruction
CT non contrast: (Sens 95%) most sensitive picks up stone >1mm, picks up obstruction
High oxalate
- Fat malabsorption: Excess fatty acid binds calcium = less calcium to bind oxalate = more free oxalate absorbed
Dx imaging or passed stone
Rx
Mg prevents Ca Ox stones
Citrate inhibits Ca stones