Does she drink tea?

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I was quickly moving along through my busy university
clinic, seeing another CKD patient when the nurse came to inform me that
the patient’s hemoglobin was critically low at 5 g/dl, while the patient
appeared to be just fine. I reviewed the rest of labs just to find out
that the iron studies were even more impressive: iron saturation 3% and
ferritin 2 ng/ml.
I inquired about the usual suspects – bleeding from various
sources – but no luck there (the patient was post-menopausal and denied GI
bleeding, later ruled out by EGD and colonoscopy)… Failing to identify a
cause of her iron deficiency, I presented the case to my staff who, after reviewing the data, asked me an unusual question: does
she drink tea? To my surprise, indeed, the patient admitted to drinking large
quantities of black tea. Still puzzled about the link between the two, I jumped
onto Google Scholar.
In the renal world, the only time when we talk about tea is
when discussing hyponatremia in patients that are on a “tea and toast” diet. So what did I find out? An interesting South African study demonstrated that black
tea inhibits non-heme iron absorption by forming iron tannate complexes. This
was confirmed by a UK study which showed that black tea
was the most potent out of all polyphenol-rich beverages (coffee, cocoa, etc.)
in inhibiting absorption of non-heme iron.
Iron deficiency anemia is common in CKD patients, one of the
latest mechanisms to be described involves the hepcidin-ferroportin axis (as
recently reviewed in JASN).
But today I discovered another one!

Posted by Tomoki Tsukahara

1 comment

  1. Hello Dr. McMahon,

    Thanks so much for your post!

    I am on daily nocturnal home hemodialysis in India. I drink about 500 ml of black tea every day. My hemoglobin is 12. My iron levels are ok. Could I be at risk of anemia.

    Thanks
    Kamal

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