Kidney Stones
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Introduction
Kidney stones are a common source of morbidity. The peak incidence is 20-45 years, with men being more than 5x affected.
The Case of...
a simple case introducing clincial presentation and calling for a differential diagnosis to get students thinking.
- question 1: (no answer necessary)
- question 2:
Causes and Risk Factors
Incidence is higher in industrialized countries, likely due to high intake of animal protein and low intake of fibre.
Calcium stones are more likely with hypercalemia (hyperthyroidism, sarcoidosis, malignancy, immobilisation), hyperoxalatemia (IBD, diets rich in oxalates such as tea, citrus, spinach, peanuts)
Pathophysiology
There are five types of renal stones (calculi).
Calcium stones are the most common, accounting for 75% of all stones. Most are composed of calcium oxalate, with the rest comprised of calcium phosphate. Calcium phosphate requires an alkalai environment to form.
Magnesium, ammonium phosphate, uric acid, and cystine are all less common.
Signs and Symptoms
- history
- physical exam
History
Kidney stones usually lead to hematuria and sudden onset of excruciating colicky pain, originating in the flank and radiating to the groin.
Polyuria, dysuria, vomiting, and ileus can also result.
The history should focus on hematuria, past stones, urinary tract infections, family history, and detailed dietary analysis.
Physical Exam
Investigations
- lab investigations
- diagnostic imaging
Lab Investigations
Initial assessment should include electrolytes, creatinine, serum calcium, phosphate, and uric acid.
Urinalysis can determine level of hematuria, rule out infection, and importantly, determine the type of crystals.
Diagnostic Imaging
Differential Diagnosis
Treatments
Management depends on type of stone, but the majority (~90%) pass spontaneously, though those 8 mm or larger likely require intervention - extracorporeal shock wave lithotripsy or ureteroscopy with basket retrieval.
All patients should drink ~3L daily to ensure at least 2L of urinary volume.
Restricting intake of animal protein and dietary salt reduces the risk of further stones.
Consequences and Course
Resources and References
Topic Development
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