A Woman with Recurrent Calcium Phosphate Kidney Stones

Abstract

SummaryKidney stones composed predominantly (50% or more) of calcium phosphate constitute up to 10% of all stones and 15%-20% of calcium stones, 80% of which are composed of calcium oxalate. Calcium phosphate is a minor component of up to 30% of calcium oxalate stones as well. The cause of calcium phosphate stones is often obscure but most often related to a high urine pH. Some patients with calcium phosphate stones may have incomplete renal tubular acidosis. Others have distal renal tubular acidosis characterized by hyperchloremic acidosis, hypocitraturia, and high urine pH. The use of carbonic anhydrase inhibitors such as acetazolamide, topiramate, and zonisamide leads to a similar picture. Treatment options to specifically prevent calcium phosphate stone recurrence have not been tested in clinical trials. Increases in urine volume and restriction of sodium intake to limit calcium excretion are important. Citrate supplementation is probably effective, although the concomitant increase in urine pH may increase calcium phosphate supersaturation and partially offset the inhibition of crystallization resulting from the increased urine citrate excretion and the alkali-associated reduction in urine calcium excretion. Thiazides lower urine calcium excretion and may help ensure the safety of citrate supplementation.

Effect of Potassium Citrate on Calcium Phosphate Stones in a Model of Hypercalciuria

“…[8][9][10][11][12][13] However, no prospective controlled studies in humans have shown the efficacy of K-cit in preventing recurrent CaP stone formation. 23 Citrate has a complex effect on urine solute excretion, and its effect on urine supersaturation with respect to CaP stone formation is difficult to predict. Some studies have shown that CaOx stones may transform into CaP stones over time, and use of citrate therapy may explain this phenomenon.…”

“…No prospective controlled trial has studied the effectiveness of citrate in reducing stone formation specifically in patients with CaP stones, and this remains an important clinical question. 23 Because CaP stone formers are characterized by alkaline urine compared with CaOx stone formers, the effect of citrate on CaP supersaturation and stone formation are difficult to predict. The alkali load would increase urine pH, increasing CaP supersaturation, whereas an increase in citrate and reduction in urinary calcium would lower CaP supersaturation; however, the net effect is uncertain.…”

A distal (type 1) renal tubular acidosis case that mimic coronary ischemia

“…12,13 According to literature, our case had a history of urinary stone disease. Furthermore, ultrasound scan revealed destruction of renal parenchyma as a result of recurrent renal stones and hydronephrosis.…”

Acetazolamide-Induced Nephrolithiasis in Idiopathic Intracranial Hypertension Patients

“…In light of our findings, acetazolamide should be administered with caution and justification. If deemed necessary to continue acetazolamide after initial stone occurrence, one might consider periodic ultrasound examinations, diet management, prophylactic urinary pH adjustments if indicated, and nephrological consultation (21,22).…”