What is the management of nephrocalcinosis?

From the Guidelines

The management of nephrocalcinosis should focus on treating the underlying cause, preventing progression, and addressing complications, with the most recent and highest quality study recommending increased fluid intake and pharmacologic monotherapy with a thiazide diuretic, citrate, or allopurinol 1.

Key Considerations

• Identifying and treating the specific etiology, such as hyperparathyroidism, distal renal tubular acidosis, or hypercalciuria, is crucial in managing nephrocalcinosis.
• Increased fluid intake of at least 2-3 liters daily is essential to dilute urine and prevent further calcium deposition, as recommended by the American College of Physicians 1.
• Dietary modifications, including moderate calcium intake, reduced sodium consumption, and limited animal protein and oxalate-rich foods, are important in preventing progression of nephrocalcinosis.

Medication Therapy

• Thiazide diuretics, such as hydrochlorothiazide, can be used to treat hypercalciuria, with a recommended dose of 12.5-50 mg daily 1.
• Potassium citrate can be used to treat distal renal tubular acidosis, with a recommended dose of 30-60 mEq daily in divided doses 1.
• Bisphosphonates can be used to treat conditions with excessive bone resorption, although the specific dose and duration of treatment are not well established 1.

Monitoring and Follow-up

• Regular monitoring of renal function, electrolytes, and urinary parameters is crucial in managing nephrocalcinosis, with follow-up imaging every 6-12 months to assess progression 1.
• Complications like urinary tract infections should be promptly treated with appropriate antibiotics to prevent further damage to the kidneys.

Goal of Treatment

• The goal of treatment is to prevent further calcium deposition in the kidneys, preserve renal function, and minimize symptoms, as nephrocalcinosis itself is generally irreversible once established 1.

From the FDA Drug Label

The changes induced by Potassium Citrate produce urine that is less conducive to the crystallization of stone-forming salts (calcium oxalate, calcium phosphate and uric acid). Increased citrate in the urine, by complexing with calcium, decreases calcium ion activity and thus the saturation of calcium oxalate Citrate also inhibits the spontaneous nucleation of calcium oxalate and calcium phosphate (brushite). The increase in urinary pH also decreases calcium ion activity by increasing calcium complexation to dissociated anions. Potassium Citrate therapy does not alter the urinary saturation of calcium phosphate, since the effect of increased citrate complexation of calcium is opposed by the rise in pH-dependent dissociation of phosphate. In patients with severe renal tubular acidosis or chronic diarrheal syndrome where urinary citrate may be very low (<100 mg/day), Potassium Citrate may be relatively ineffective in raising urinary citrate. A higher dose of Potassium Citrate may therefore be required to produce a satisfactory citraturic response The effect of oral Potassium Citrate therapy in a non-randomized, non-placebo controlled clinical study of five men and four women with calcium oxalate/calcium phosphate nephrolithiasis and documented incomplete distal renal tubular acidosis was examined Potassium Citrate therapy was associated with inhibition of new stone formation in patients with distal tubular acidosis. The stone-passage remission rate was 67%. All patients had a reduced stone formation rate.

The management of nephrocalcinosis involves the use of Potassium Citrate to reduce the formation of calcium stones by increasing urinary citrate and pH, thereby decreasing calcium ion activity and the saturation of calcium oxalate.

• The dosage of Potassium Citrate may need to be adjusted based on the patient's condition, with higher doses required for patients with severe renal tubular acidosis or chronic diarrheal syndrome.
• Patients should be instructed to stay on a sodium restricted diet and to reduce oxalate intake.
• A moderate calcium restriction may also be imposed on patients with hypercalciuria.
• The treatment should be monitored regularly to assess its effectiveness in reducing stone formation rate 2.

From the Research

Management of Nephrocalcinosis

The management of nephrocalcinosis involves addressing the underlying cause of the condition.

• The treatment approach may vary depending on the etiology, with hereditary tubulopathy and hyperoxaluria being common causes in children 3.
• In some cases, thiazide diuretics may be used to reduce urinary calcium excretion, as seen in a child with Lowe syndrome 4.
• Increased fluid intake and correction of metabolic acidosis are also important interventions, although they may not always be successful 5.
• Early initiation of appropriate etiological treatment is recommended to prevent or delay the progression to chronic kidney disease in some cases 5.

Key Considerations

• Family history, clinical context, and complete laboratory data are essential in providing a specific diagnosis 5.
• Nephrocalcinosis can be classified according to the radiological type: medullary, cortical, or diffuse 5.
• The condition can lead to chronic kidney disease, emphasizing the need for prompt and effective management 5, 3.
• Animal model studies have shed light on the mechanisms of nephrocalcinosis, including the role of urinary supersaturation and crystallization modulators 6.

Treatment Outcomes

• The outcome of treatment can vary, with some patients experiencing improvement in renal function, while others may have unchanged or declining function 7, 3.
• A study of children with nephrocalcinosis found a decrease in estimated glomerular filtration rate over a median follow-up of 38 months 3.
• Further research is needed to understand the causes and optimal management of nephrocalcinosis, particularly in rare cases or those with underlying genetic disorders 5, 3.