Calcium Nephrolithiasis

See Also

Epidemiology

Represents more than 75% of Nephrolithiasis cases
Males predominance
Most common in hot, dry environments

Risk Factors

Evaluation
General

Do not perform evaluation during hospitalization
Single Stone episodes with no residual stones
1. Serum Calcium
2. Consider 24 hour urine
  1. Urine Volume
  2. Urine Calcium
Recurrent (1 stone per 3 years or more), Residual or Family History of stones
1. Urine Volume
2. Conside Creatinine Clearance
3. Urine Calcium (Hypercalciuria >300 mg/day)
4. Urine Sodium
5. Urine Uric Acid (Hyperuricosuria >750 mg/day)
6. Urine Oxalate (Hyperoxaluria >40 mg/day)
7. Urine Citrate (Hypocitraturia <320 mg/day)

Evaluation
Stone Type

Mixed Calcium Oxalate and Phosphate (See above)
1. Hypercalciuria (50%)
2. Low Urine Volume (30-50%)
3. Hyperoxaluria (20-30%)
4. Hypocitraturia (20-30%)
5. Hyperuricosuria (20%)
Pure Calcium Phosphate Stones (uncommon)
1. Causes
  1. Pregnancy (account for up to 75% of Nephrolithiasis in pregnancy)
  2. Distal Renal Tubular Acidosis
  3. Primary Hyperparathyroidism
  4. Excessive alkalinization
  5. Sarcoidosis
2. Obtain Serum Electrolytes
  1. Hyperkalemia
  2. Serum Bicarbonate increased
  3. Hyperchloremia

Evaluation
Specific Populations

Hmong patients more commonly have increased Uric Acid
African americans rarely form Calcium Stones
1. Evaluate if Hypercalciuria and Hypercalcemia
2. Underlying causes
  1. Sarcoidosis
  2. Primary Hyperparathyroidism

Management
Calcium Oxalate Stones

See Nephrolithiasis for general prevention
Increase fluid to 2.5 to 3 Liters per day (twelve 8 oz glasses)
1. Goal Urine Output 2 Liters
Avoid soft drinks (esp. colas which contain phosphoric acid, predisposing to stone formation)
Check Serum Vitamin D and replace if Vitamin D Deficiency
Hypercalcemia
1. Obtain Parathyroid Hormone to evaluate for Hyperparathyroidism
Normocalcemia and uncomplicated Calcium Stone disease
1. Normocalciuria
  1. Potassium Citrate (Urocit-K) 20 meq orally three times daily with meals
  2. Monitor Potassium at baseline, 2 weeks and then annually
2. Hypercalciuria (>250 mg/day)
  1. Increase Dietary Calcium 1000-1200 mg/day
    1. Calcium binds oxalate in the intestinal tract
    2. Take Calcium only with meals
    3. Take Calcium as food not Calcium supplement
  2. Follow Low Sodium Diet (<2.3 - 4 g/day)
  3. Decrease dietary meat intake
  4. Avoid Loop Diuretics (e.g. Lasix)
  5. Alkaline citrate 9-12 grams/day divided 3 times daily within 30 minutes of meals or bedtime
    1. May also use unsweetened lemonade instead or lemon juice
    2. No evidence for the use of cranberry juice supplementation in Calcium Stone prevention
  6. Medications: Thiazide Diuretic with Potassium
    1. Hydrochlorothiazide 25 to 50 mg orally daily (or Chlorthalidone) AND
    2. Potassium supplement
      1. Normocitraturia:
        Potassium chloride
      2. Hypocitraturia:
        Potassium citrate 20 meq orally three times daily
        Monitor Potassium at baseline, 2 weeks and then annually
  7. Medications: Other
    1. Allopurinol 100 mg daily, then advance to 3 times daily
      1. Indicated in Calcium Stones regardless of Uric Acid level
Hyperoxaluria
1. May empirically follow Low Oxalate Diet
2. Mild Hyperoxalauria (40-60 mg/day)
  1. Normal Dietary Calcium
  2. Low Oxalate Diet
  3. Decrease Ascorbic Acid <1-2 grams/day
3. Enteric Hyperoxaluria (60-80 mg/day)
  1. Calcium Supplements with meals
  2. Magnesium 200-400 mg/day
  3. Low Fat Diet
  4. Trial of Cholestyramine 2-4 grams per meal
4. Primary Hyperoxaluria (>80 mg/day)
  1. Trial Pyridoxine (Vitamin B6)
  2. Monitor Renal Function frequently
  3. Referral to Hepatology

Management
Calcium Phosphate Stones

Pregnancy Test if not already done
Decrease Sodium intake (limits Calcium excretion)
Limit to moderate use of animal Protein (beef, chicken, pork, organ meats, fish, eggs, milk)
Maximize diet of fruits, vegetables and whole grains
Maintain citrate intake (see above)
Consider Thiazide Diuretics (see above)
Goldfarb (2012) Clin J Am Soc Nephrol 7(7):1172-8 +PMID: 22595827 [PubMed]

Prognosis

Recurrence risk within 2 years: 35%

References