calcium oxalate stone
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Introduction
75-85% of all renal stones contain calcium.
Etiology
- hypercalciuria
- hyperoxaluria
- calcium oxalate
- patients must have an intact colon to absorb oxalate
- free oxalate is increased by free fatty acids competing for Ca+2 & Mg+2, usual binders of oxalate
- fatty acid & bile salts increase permeability to oxalate
- orlistat inhibits absorption of fatty acids & bile salts & increases risk of hyperoxaluria
- factors increasing hyperoxaluria
- decreased water absorption
- decreased bicarbonate absorption
- decreased absorption of inhibitors
- recessive disorder in oxalate metabolism
- inflammatory bowel disease
- roux-en-Y gastric bypass surgery[5]
- reduced inhibitor excretion
- primary hyperparathyroidism
- sarcoidosis
Epidemiology
- most common in 3rd to 5th decade of life
Pathology
- 1,25-dihydroxyvitamin D3 levels may be increased
- inappropriate calciuria may occur with calcium-restricted diets
- calcium oxalate stones form in acidic urine
Laboratory
- serum PTH
- renal function tests
- urinalysis & culture
- 24 hour urine:
- hypercalciuria: > 300 mg (men) or 250 mg (women) or > 4 mg/kg in 24 hours
- creatinine
- uric acid
- 24 hour urine volume
- serum Ca+2 is generally normal
- stone analysis
Management
- correcting dietary stresses
- Na+ increases urinary Ca+2
- diet of < 3 g of salt/day[4]
- animal protein increases urinary Ca+2
- Na+ increases urinary Ca+2
- increasing urine volume > 2.5L/day
- thiazide diuretics for hypercalciuria
- Na+ must be restricted for urine Ca+2 to decrease by 50%
- development of hypercalcemia suggests latent hyperparathyroidism
- amiloride may also be of benefit
- patients with primary hyperparathyroidism & urolithiasis
- removal of parathyroid adenoma
- reduce intestinal absorption of oxalate
- increase dietary calcium, decrease dietary oxalate & fat may reduce intestinal absorption as oxalate[3][4]
- calcium citrate (Citracal) may be best form[4]
- cholestyramine to bind bile acids (enteric hyperoxaluria)
- replacement of inhibitor substances
More general terms
Additional terms
References
- ↑ Mayo Internal Medicine Board Review, 1998-99, Prakash UBS (ed) Lippincott-Raven, Philadelphia, 1998, pg 615
- ↑ Medical Knowledge Self Assessment Program (MKSAP) 11, 16, 17. American College of Physicians, Philadelphia 1998, 2012, 2015
- ↑ 3.0 3.1 Journal Watch 22(3):20, 2002 Borghi et al, N Engl J Med 346:77, 2002
- ↑ 4.0 4.1 4.2 4.3 4.4 Prescriber's Letter 9(3):18 2002
- ↑ 5.0 5.1 Maalouf NM, Tondapu P, Guth ES, Livingston EH, Sakhaee K. Hypocitraturia and hyperoxaluria after Roux-en-Y gastric bypass surgery. J Urol. 2010 Mar;183(3):1026-30. PMID: https://www.ncbi.nlm.nih.gov/pubmed/20096421
- ↑ NEJM Knowledge+ Nephrology/Urology
- ↑ 7.0 7.1 Johansson G, Backman U, Danielson BG et al Effects of magnesium hydroxide in renal stone disease. J Am Coll Nutr. 1982;1(2):179-85 PMID: https://www.ncbi.nlm.nih.gov/pubmed/6764473