Colon cancer

December 29, 2020 10:13 AM

I am being urged to get a colonoscopy (which, fine, I'll get one) to see if my chronically low ferritin is due to intestinal blood loss. It has been just as low as it is now (3, I forget the units), for at least 16 years. IV iron helps, then it drops again. If colon cancer had been advanced enough to deplete my ferritin stores for 16 years, wouldn't I be symptomatic by now? I can't get a straight answer out of my provider and feel like this is more of a CYA recommendation. I mean, I need one anyway because of my age, but I want to understand whether cancer is actually likely to be the cause, as opposed to my heavy periods.
posted by Bluesocking to Health & Fitness (12 answers total)

How far have your heavy periods been investigated? That's the first thing my docs investigated with my chronic anemia. I probably need to have a uterine ablation but I'm being a chicken about it.
posted by cooker girl at 10:54 AM on December 29, 2020

Response by poster: Yeah, I asked if I could do a fecal occult blood test and they said it's nowhere near as sensitive. But aren't they routinely using these instead of colonoscopy in Canada? I am not crazy about having another medical procedure right now. If I'm losing that much blood, wouldn't it pick it up?
posted by Bluesocking at 10:54 AM on December 29, 2020

Response by poster: cooker girl—I do have a big inoperable fibroid in my uterine wall.
posted by Bluesocking at 10:59 AM on December 29, 2020 [1 favorite]

For years now, my post-menopausal mother has been getting periodic iron infusions and the occasional blood transfusion. No one knows why, but they do know it’s definitely not colon cancer. Best guess is an intestinal bleed that heals before they have a chance to look in there.
posted by Ruki at 11:03 AM on December 29, 2020

You are right that colon cancer would have manifested by now if it had been the cause of your iron deficiency 16 years ago but as you note, depending on your age and risk factors you might be a candidate for colon cancer screening anyway and more importantly, colonoscopy can find other causes of anemia. One example is colonic angiodysplasias - can cause chronic low-volume blood loss (with or without change in stool color) and usually have no other symptoms.

Fecal occult blood testing is used as a screening tool for colon cancer in healthy average risk individuals but it cannot be used to rule out chronic GI blood loss as bleeding may be intermittent (and not detectable at the time of the test even if it's substantial enough to cause iron deficiency).

Also, this is a bit tangential but I always make sure to evaluate my patients with iron deficiency for celiac disease.

Hope this helps - this is obviously not intended as medical advice.
posted by M. at 11:52 AM on December 29, 2020 [4 favorites]

Years ago I saw an article where someone compiled a bunch of numbers and concluded that while anemia in menstruating people is often attributed to menstruation (and therefore not given much diagnostic attention) the data didn't clearly support that assumption. Unfortunately I can't find it - it was thorough but not a published journal article - but this study kind of pokes at the same possibility.
posted by needs more cowbell at 12:39 PM on December 29, 2020

IANYD but I am a hematologist and an oncologist. For people who menstruate,, it is generally felt that heavy menstrual bleeding is the most likely cause. However, I have a very low threshold to refer for colonoscopy and EGD, especially if anemia is long in course or people don’t readily correct with iron supplementation. It’s true that it’s unlikely that you wouldn’t be symptomatic from a long-standing colon cancer. Anecdotally, though, I can tell you that I have found pretty large polyps (which turned out to be precancerous) and some early colon cancers in people for whom guidelines would not have dictated for GI evaluation.

Also - not knowing how old you are, or where you are located, most of the major GI societies, ACS, and now the USPSTF are recommending initial screening colonoscopy at age 45. This is due in large part to epidemiological data that suggests a trend toward earlier occurrence of colon cancer.

As M. also says, endoscopic evaluation helps identify other potential sources of GI blood loss and malabsorption. It is an intervention that can be both diagnostic *and* therapeutic. Even tests like Cologuard are not rated to test for polyps that can become cancer - only colon cancer itself.
posted by honeybee413 at 12:41 PM on December 29, 2020 [6 favorites]

Hey there! This sounds similar to something my dad experienced a few years back. He had chronically low iron for a decade, and when he finally got around to getting a colonoscopy, they discovered that his colon was significantly longer than average. Turns out he had a gigantic polyp in the "bonus colon" section that was interfering with iron absorption. Polyp and 10" of extra colon were removed (which now means he has an average length colon), and his iron levels returned to normal pretty quickly.
posted by Vervain at 12:57 PM on December 29, 2020

I always make sure to evaluate my patients with iron deficiency for celiac disease.

Just coming here to mention that I had a local friend who had decades-long mystery anemia that turned out to be celiac.
posted by jessamyn at 1:44 PM on December 29, 2020

My mother is having the same situation, except it’s only been for the past one year instead of sixteen. She’s scheduled for a colonoscopy/endoscopy in February, and her doctor says he’s pretty sure it’s not cancer. He suspects a more generic intestinal bleeding or stomach ulcer. So that’s a possibility.

Silver lining: I have never had anything in my life that made me feel as good as the colonoscopy sedation.
posted by The Underpants Monster at 4:27 PM on December 29, 2020 [2 favorites]

Lisinipril and other ace inbitors used to control blood pressure, can cause anemia as a side effect. Take your iron rich meal at lunch with a source of vitamin C, don't eat calcium rich foods, tea or eggs at least one hour before or after your iron rich meal or when taking your supplimental iron. Don't take Iron on an empty stomach or before bed, it is hard on the stomach lining. Iron is also constipating, just go with one dose a day at lunch. Breakfast is when people like to take milk with cereals, and coffee etc. A lot of people like milk in the evening. Always exami e the side effects of meds you take, especially when something new crops up.
posted by Oyéah at 4:54 PM on December 29, 2020

This may seem off-topic, but do you or other relatives (parent/sibling/grandparents) get unusual nosebleeds? You may want to look at info about Hereditary Hemorrhagic Telangiectasia.
Your medical team may need to do some sleuthing into family history, but 90% of those with this condition don't know they have it, and it can cause anemia because of GI bleeding due to blood vessel malformations typical of the disorder.
posted by It's_pecano at 6:30 AM on December 30, 2020