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    Card DI-007
Acquired trait of passing red urine after eating beets
Back of Card DI-007
  • beeturia

Differential Diagnosis

  • iron deficiency


Beet pigment (betacyanin) is renally excreted, and colors acidic urine pink to deep red. Fourteen percent of normal persons develop visible beeturia after ingesting beets, perhaps on a genetic basis (McKusick 10960).

However, when 100 g of small beets ("much more than anyone would eat from free choice") were fed to patients with untreated iron deficiency anemia,1 80% developed beeturia. Of 15 similar patients who had already received iron, only one developed beeturia, suggesting that betacyanin absorption, and hence beeturia, occurs at times of "iron hunger." Consistent with this was the 46% incidence of beeturia in pernicious anemia patients (augmented iron absorption occurs in this disease during vitamin B12 treatment) and the 33% incidence in non-anemic patients with both malabsorption and biopsy-proven jejunal atrophy1 (the jejunum plays an important role in iron absorption2).

It has been suggested that iron and betacyanin compete for an intestinal acceptor substance, with iron the preferred ligand. Because beeturia can appear and disappear in normals, at least some of the "baseline" 14% incidence may be due to the fluctuating nature of iron absorption in normal people.1

Other effects of vegetables on the sensorium include the olfactory repercussions of asparagus metabolites in urine (McKusick 10840) and the way artichokes make water taste sweet to some individuals (McKusick 10832).


(l) Br Med J. 2:271-973 (1963). Study from Scotland.

(2) Annu Rev Med. 34: 55-68 (1983). Review of iron absorption.

   Zebra Cards: An Aid to Obscure Diagnoses. JG Sotos. Philadephia: American College of Physicians, 1989. ISBN 0-943126-13-4. Copyright © 1989 American College of Physicians. All Rights Reserved. Phone: 1-800-523-1546.
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©1986-2000 John Sotos, MD. All rights reserved.

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