📋 Key Information Summary
- Nephrolithiasis affects ~10% of Australians, with recurrence rates up to 50% within 10 years without preventive strategies.
- Calcium oxalate/phosphate stones account for 70–80% of cases; uric acid, struvite, and cystine stones are less common.
- Non-contrast CT KUB is the gold-standard investigation for acute flank pain, with >95% sensitivity for stones >2 mm.
- First presentation or high-risk stones warrant a 24-hour urine metabolic work-up to guide specific prevention.
- Management is guided by stone size, location, composition, and degree of obstruction.
- Medical expulsive therapy with tamsulosin 400 mcg daily for up to 4 weeks is first-line for distal ureteric stones ≤10 mm.
- Shockwave lithotripsy (SWL) is first-line for renal stones <20 mm and proximal ureteric stones <10 mm.
- Ureteroscopy with laser lithotripsy has higher stone-free rates than SWL for most ureteric stones and renal stones <20 mm.
- Struvite (infection) stones require complete surgical removal and targeted antibiotic therapy to prevent recurrence.
- All patients should receive fluid intake advice (>2.5 L/day) and dietary modification based on stone composition.
- Aboriginal and Torres Strait Islander peoples have higher rates of renal disease and may face barriers to timely specialist care.
Introduction & Australian Epidemiology
Nephrolithiasis (kidney stone disease) is a common and painful condition characterised by the formation of hard mineral and salt deposits within the urinary tract. In Australia, the lifetime prevalence is approximately 10–15%, with a male-to-female ratio of 3:1. The peak incidence is between ages 30–60 years.
Recurrence is a major concern, with ~50% of patients experiencing a recurrence within 10 years without preventive intervention. The economic burden is significant, encompassing emergency presentations, surgical procedures, and lost productivity.
Stone composition varies, with calcium-based stones (oxalate and phosphate) predominating. Accurate diagnosis, identification of modifiable risk factors, and appropriate acute management are essential to reduce morbidity and prevent long-term recurrence.
Stone Types & Pathophysiology
Stone formation (lithogenesis) occurs when urinary constituents supersaturate and crystallise. Key factors include urine volume, pH, and the concentration of stone-forming salts and inhibitors.
Major Stone Types
| Stone Type | Frequency | Key Associations | Radiodensity (CT) |
|---|---|---|---|
| Calcium Oxalate | ~70% | Hypercalciuria, hyperoxaluria, low urine volume, hypocitraturia | High (bright white) |
| Calcium Phosphate | ~10–15% | Renal tubular acidosis, hyperparathyroidism | High |
| Uric Acid | ~10% | Acidic urine (pH <5.5), gout, metabolic syndrome | Moderate (less dense) |
| Struvite (Infection) | ~5–10% | Urease-producing bacteria (e.g., Proteus, Klebsiella) | Variable |
| Cystine | ~1% | Autosomal recessive defect in dibasic amino acid transport | Moderate |
Pathophysiology note: Calcium stones often form on Randall's plaques (renal papillary calcifications). Uric acid stones form due to persistent acidic urine, not hyperuricosuria alone.
Clinical Features & Diagnosis
Clinical Presentation
- Classic renal colic: Sudden, severe, colicky flank pain radiating to the groin or labia/testis. Patient is typically restless and unable to find a comfortable position.
- Associated nausea, vomiting, and haematuria (microscopic in ~80%).
- Signs of obstruction or infection: fever, rigors, sepsis, or anuria (bilateral obstruction) require urgent intervention.
Diagnostic Investigations
ESSENTIAL
Non-contrast CT KUB
Gold standard for acute presentation. Sensitivity >95% for stones >2 mm. Also identifies alternative diagnoses (e.g., AAA). MBS item 56001 (CT abdomen/pelvis).
AVAILABLE
Urinalysis & Culture
Essential to detect haematuria and concurrent UTI. Microscopic haematuria is absent in ~20% of cases.
AVAILABLE
Blood Tests
FBC, CRP, UEC, calcium, phosphate, urate, PTH (if hypercalcaemia). Assess renal function and infection.
AVAILABLE
Plain KUB X-ray
Useful for follow-up of known radiopaque stones (calcium, struvite). Poor sensitivity for uric acid and small stones. MBS item 58505.
CONSIDER REFERRAL
Low-dose CT or Ultrasound
Ultrasound first-line in pregnancy or paediatrics. Low-dose CT for recurrent stone formers to reduce radiation exposure.
Red flags for immediate urology referral: Suspected sepsis with obstruction, solitary kidney with obstruction, bilateral obstruction, acute kidney injury, or intractable vomiting/pain.
Metabolic Work-up & Risk Factors
Indications for Metabolic Evaluation
- First-time stone formers with high-risk features (family history, solitary kidney, chronic diarrhoea, obesity, diabetes).
- All recurrent stone formers.
- Patients with struvite or cystine stones.
24-Hour Urine Collection
The cornerstone of metabolic work-up. Two collections are recommended on unrestricted diet.
| Parameter | Normal Range | Clinical Significance |
|---|---|---|
| Volume | >2.5 L/day | Low volume increases supersaturation risk |
| Calcium | <6.2 mmol/day (women) <7.5 mmol/day (men) |
Hypercalciuria is the most common abnormality |
| Oxalate | <0.46 mmol/day | Elevated in primary hyperoxaluria or high-oxalate diet |
| Citrate | >1.9 mmol/day (women) >2.5 mmol/day (men) |
Hypocitraturia promotes calcium stone formation |
| Urate | <4.5 mmol/day | Can promote calcium or uric acid stones |
| pH | 5.8–6.2 | Persistently low (<5.5) favours uric acid; high (>6.2) favours phosphate |
Common Modifiable Risk Factors
1
Low Fluid Intake
Aim for urine output >2.5 L/day. Spread evenly through day and night.
2
Dietary Factors
High sodium (increases calcium excretion), high animal protein, high oxalate foods (spinach, rhubarb, nuts), low calcium intake.
3
Obesity & Metabolic Syndrome
Insulin resistance promotes acidic urine and uric acid stones.
Management
Acute Renal Colic Management
Diclofenac
Voltaren® · NSAID
Adult dose
75 mg IM/IV initially, then 50 mg PO TDS for 3–5 days
Paediatric dose
1 mg/kg PO/PR (max 75 mg) TDS
Renal adjustment
Avoid if eGFR <30 mL/min
PBS status
✔ PBS General Benefit
Oxycodone
Endone® · Opioid
Adult dose
5–10 mg PO/SC 4–6 hourly PRN for breakthrough pain
Key caution
Short-term only. Risk of dependence.
PBS status
✔ PBS General Benefit
Tamsulosin
Flomaxtra® · Alpha-blocker
Adult dose (MET)
400 mcg PO daily for up to 4 weeks for distal ureteric stones ≤10 mm
PBS status
✔ PBS Authority Required
Definitive Management by Stone Size & Location
Observation / MET
Distal ureteric stone ≤10 mm
Trial of medical expulsive therapy (tamsulosin 400 mcg daily) + analgesia for 4 weeks. >70% spontaneous passage rate.
Setting: GP/ED with urology follow-up
SWL or URS
Renal stone <20 mm or ureteric stone >10 mm
SWL first-line for renal stones <20 mm (if not lower pole). URS has higher single-procedure stone-free rate for ureteric stones.
Setting: Urology outpatient
PCNL or URS
Renal stone ≥20 mm or staghorn
Percutaneous nephrolithotomy (PCNL) is gold standard for large stones. Complete removal essential for struvite stones.
Setting: Major centre with endourology expertise
Medical Prevention by Stone Type
Indapamide
Dapa-Tabs® · Thiazide-like diuretic
Adult dose
2.5 mg PO daily (for hypercalciuria)
Mechanism
Reduces urinary calcium excretion
PBS status
✔ PBS General Benefit
Potassium Citrate
Urocit-K® · Alkalinising agent
Adult dose
10–20 mEq PO BD-TDS (for hypocitraturia or uric acid stones)
Target urine pH
6.0–6.5 for calcium stones; 6.5–7.0 for uric acid/cystine
PBS status
✘ Not PBS
Allopurinol
Allohexal® · Xanthine oxidase inhibitor
Adult dose
100–300 mg PO daily (for hyperuricosuria)
PBS status
✔ PBS General Benefit
Special Populations
Pregnancy
Diagnosis
Ultrasound is first-line (avoid radiation). MRI without contrast is second-line.
Management
Conservative management preferred. Ureteric stent or nephrostomy if obstruction with infection. URS safe in 2nd/3rd trimester.
Paediatrics
Diagnosis
Ultrasound first-line to avoid radiation. Low-dose CT if inconclusive.
Considerations
Always perform metabolic work-up. Consider anatomical abnormalities, genetic disorders (e.g., cystinuria).
Chronic Kidney Disease
NSAIDs
Contraindicated if eGFR <30. Use paracetamol or opioids cautiously.
Contrast
Avoid iodinated contrast if eGFR <45. Non-contrast CT preferred.
Infection Stones
Struvite stones
Require complete surgical clearance (PCNL/URS) and culture-directed antibiotics for 1–2 weeks post-op. Acetohydroxamic acid (not PBS) may be adjunctive.
Aboriginal and Torres Strait Islander Health
📚 References
- 1. Australian Institute of Health and Welfare (AIHW). Kidney stones in Australia. Canberra: AIHW; 2023.
- 2. The Royal Australian College of General Practitioners (RACGP). Guidelines for preventive activities in general practice (Red Book). 10th ed. East Melbourne: RACGP; 2023.
- 3. Urological Society of Australia and New Zealand (USANZ). Position statement on the management of ureteric calculi. BJU Int. 2022;129(5):611-620.
- 4. Kidney Health Australia. Chronic kidney disease (CKD) management in primary care. 4th ed. Melbourne: Kidney Health Australia; 2020.
- 5. National Health and Medical Research Council (NHMRC). Australian guidelines to reduce health risks from drinking alcohol. Canberra: NHMRC; 2020.
- 6. Turnbull D, et al. Medical expulsive therapy for ureteric stones: a systematic review and meta-analysis. Med J Aust. 2021;214(8):375-381.
- 7. Turk C, et al. EAU Guidelines on Diagnosis and Conservative Management of Urolithiasis. Eur Urol. 2022;82(3):284-299.
- 8. Pearle MS, et al. AUA/CUA/SUFU Guideline: Surgical Management of Stones. J Urol. 2016;196(4):1153-1160.
- 9. Aboriginal and Torres Strait Islander Health Performance Framework. Kidney health. Australian Institute of Health and Welfare; 2023.
- 10. Moe OW. Kidney stones: pathophysiology and medical management. Lancet. 2006;367(9507):333-344.
- 11. Services Australia. Medicare Benefits Schedule (MBS) Item 56001, 58505. Canberra: Australian Government; 2024.
- 12. Australian Commission on Safety and Quality in Health Care (ACSQHC). National Safety and Quality Health Service Standards. 2nd ed. Sydney: ACSQHC; 2021.