Posted by HFHS M.D.-MS on January 08, 1998 at 21:12:15:

In Reply to: Kidney Stones & Vitamin C? posted by J. Kelly on January 02, 1998 at 15:51:03:

: Dear Doctor:

Can you give me information or refer me to articles on the connection between kidney stones and excess intake of vitamin c?

Thank you for your question.

About 90% of kidney stones are made when oxalate binds to calcium. Oxalate does not dissolve very well in urine and therefore it plays an important part of initial stone formation when it precipitates. Vitamin C or ascorbic acid is broken down in the intestine to oxalate. Patients who have intestinal abnormalities which cause them to absorb oxalate at an increased rate are at risk of forming stones if they “overdose “ on vitamin C. Usually 2 grams ( 2000 mg) a day is considered a high dose.

Campbell’s Urology, 7 Th. edition, 1998, Volume #3, page 2673 states that eighty percent of the oxalate found in urine comes from endogenous production in the liver ( it is made in the body) 40% from ascorbic acid , 40% from glycogen ( an amino acid) and 10% come from dietary sources.

Tselius ,HG wrote The Diurnal excretion of oxalate and the effect of pyroxidine and ascorbate on oxalate excretion. European Urology 1977; 3:41-46 This is the abstract.

Country of Publication Switzerland

Abstract

The diurnal urinary oxalate excretion has been determined in 11 patients with urolithiasis and in 7 normal subjects. Increased excretion following meals was observed. The variation from hour to hour was most pronounced in the stone patient group. The relation between oxalate concentration and urinary volume was found to follow a biphasic exponential course. Pyridoxine administration increased oxalate excretion in 9 out of 12 subjects and decreased the excretion in 3 subjects. Ascorbate administration increased oxalate excretion in all 7 subjects studied.

ISSN 0302-2838

Here are a few more recent articles from medline. These articles are also quite technical in nature.

Wong K. Thomson C. Bailey RR. McDiarmid S. Gardner J. Acute oxalate nephropathy after a massive intravenous dose of vitamin C. [Journal Article] Australian & New Zealand Journal of Medicine. 24(4):410-1, 1994 Aug.

. Chalmers A. Re: Ascorbate acid overdosing: a risk factor for calcium oxalate nephrolithiasis [letter; comment]. [Comment. Letter] Journal of Urology. 152(1):171, 1994 Jul.

Costello J. Re: Ascorbic acid overdosing: a risk factor for calcium oxalate nephrolithiasis [letter; comment] [see comments]. [Comment. Letter] Journal of Urology. 149(5):1146, 1993 May.

This information is provided for general medical education purposes only. Please consult your physician for diagnostic and treatment options pertaining to your specific medical condition. More individualized care is available through our renal stone specialists, Drs. Menon (313-876-2066) and Littleton (313-876-1814).

Hope this helps.

Sincerely
HFHS M.D.-MS
*KEYWORD: urinary lithiasis