If a patient presents with nephrolithiasis and the following urinalysis, what type of stone would you suspect? How would you manage this patient?
Calcium oxalate dihydrate – enveloped shaped crystals
Calcium oxalate monohydrate – dumbbell, spindle shaped crystals
The mainstain of treatment of calcium oxalate stones is to increase fluid intake to reach the goal of at least 2 L of urine output per day. A reduction in calcium excretion by a low sodium diet (80-100 meg/day) may also be suggested. Low sodium excretion will enhance proximal sodium and calcium absorption, thereby decreasing urinary calcium excretion and stone formation.
Drug therapy can also be added depending on the cause. If there is hypercalciuria, thiazide diuretics may be helpful. Potassium citrate can be used in cases of hypocitraturia and type 1 renal tubular acidosis. For hyperuricosuria, treatment of choice would be allopurinol or potassium citrate.
For additional information, try this free full text reference:
Ross Morton, Eduard A. Iliescu, and James W.L. Wilson.
Nephrology: 1. Investigation and treatment of recurrent kidney stones. CMAJ, Jan 2002; 166: 213 – 218 (PubMed)