BG testing and anaemia

[markd]

in all the packets of test strips, there is a paper insert with a mass of small text - including a warning that low hematocrit or anaemia will cause a false high reading.

My fasting levels, usually 4.6 - 4.8 edged up over a couple of months to 5.4 to 5.5 so I restarted on Metformin again. Didn't seem to make much difference, in that tests were still a bit higher than I'd expect. After I restarted the Met, I started to get occasional sort-of hypo feelings again a couple of hours after meals, but still reading 5.5 to 6.0

Anyway, turned out I was a bit anaemic again (happens occasionally - as in every 4 or 5 years perhaps) - was given a one month course of Ferrous Sulphate tabs (makes your poo turn black!) and now back to the usual fasting and 2hr PP readings of 4.6 again with no Met.

Been advised to take a daily multivitamin pill, just in case my diet is a bit deficient.

Looking back, I realise that I was tending to feel the cold in fingertips, ears and tip of my nose more than usual and that I'd occasionally get white skin on my fingers almost like Reynauds syndrome, if I was outside in the cold with no gloves. My father diagnosed as suffering from Reynauds many years ago - now I wonder if he might have been a bit anaemic too.

Results were dramatically fast - I'd been at the higher levels reliably for well over a month, but in less than a week of starting on the pills, I was back down to normal.

There doesn't seem to be any underlying cause of the occasional bouts of anaemia - diet and age, I think; I had put on a few pounds at the end of last year and have been trying to get them off again.

Anyone else actually experienced false high readinsg like this?


MArk

 

[cugila]

I recently posted this in another thread which was about HbA1c and Anaemia........blowed if I can find it now ! Anyway, I have no reason to suppose that a normal Bg test will not also be affected by certain types of Anaemia. Read below:

HbA1c is an index used in the management of patients with diabetes. HbA1c measurements rely on a predictable effect of glucose concentration on hemoglobin (Hb) over a normal red blood cell (RBC) life span - however any condition that alters RBC survival may invalidate HbA1c as an accurate measure of glycaemic control.

Hemolytic anaemias results in decreased RBC survival and hence reduced HbA1c;
Iron deficiency anaemia results in a modest reduction in RBC survival, hence a lower level HbA1c.

So, if you are Anaemic, yes your Bg levels should show a difference.

Ken.

 

[markd]

Interesting - so anaemia results in a falsely high BG reading *and* a falsely low A1c then.

I'm not due for an A1c for a few months - I might get one of the cheap A1c-by-post kits to see what is going on.

Main thing, though, is that I'm happy my numbers have come back to usual values.

Mark

I recently posted this in another thread which was about HbA1c and Anaemia........blowed if I can find it now ! Anyway, I have no reason to suppose that a normal Bg test will not also be affected by certain types of Anaemia. Read below:

HbA1c is an index used in the management of patients with diabetes. HbA1c measurements rely on a predictable effect of glucose concentration on hemoglobin (Hb) over a normal red blood cell (RBC) life span - however any condition that alters RBC survival may invalidate HbA1c as an accurate measure of glycaemic control.

Hemolytic anaemias results in decreased RBC survival and hence reduced HbA1c;
Iron deficiency anaemia results in a modest reduction in RBC survival, hence a lower level HbA1c.

So, if you are Anaemic, yes your Bg levels should show a difference.

Ken.

 

[cugila]

Interesting - so anaemia results in a falsely high BG reading *and* a falsely low A1c then.

Mark

Hi Mark.
Erm......... :?

That's not strictly true.......the bit about falsely low HbA1c readings is proven. There is evidence for that.

However I only said that the Bg levels will show a difference....not that they will be high.
I do not have any evidence stating that. The fact that your BG levels went high may have nothing whatsoever to do with the Anaemia......and then again it might ! There just isn't any evidence I have found to support that.

Ken.

 

[markd]

Quite right - I was relying on the package insert with the test strips that says low hematocrit values and anaemia will cause false high readings (and the reverse is true also).

http://www.lifescan.com/pdf/ultra_teststrip_insert.pdf

Interstingly, on looking further I find that anaemia will likely lead to higher HbA1c values, which resolve after iron supplememnts are given.:

-----------
Title: Effect of iron deficiency anemia on the levels of hemoglobin A1c in nondiabetic patients (1).
Results: “Before iron treatment, the mean HbA1c (7.4 +/- 0.8%) level in patients with IDA was higher than in a healthy group (5.9% +/- 0.5) (p < 0.001). In patients with IDA, HbA1c decreased significantly after iron treatment from a mean of 7.4% +/- 0.8 to 6.2% +/- 0.6 (p < 0.001). Iron deficiency must be corrected before any diagnostic or therapeutic decision is made based on HbA1c.”

Title: The effect of iron deficiency anaemia on the levels of haemoglobin subtypes: possible consequences for clinical diagnosis (2).
Results: “HbA1C fell significantly after iron treatment, from a mean of 6.15% +/- 0.62 to 5.25% +/- 0.45 (P < 0.001). In conclusion, iron deficiency must be corrected before making any diagnostic or therapeutic decisions based on HbA2 and HbA1C levels.”

Title: Effects of iron deficiency anemia on hemoglobin A1c in type 1 diabetes mellitus (3)
Results: “We conclude that among type 1 DM patients with similar level of glycemia, iron deficiency anemia is associated with higher concentrations of HbA1c. In addition, iron replacement therapy leads to a drop in HbA1c in both diabetic and non-diabetic patients. The iron status of the patient must be considered during the interpretation of HbA1c concentrations in type 1 DM.”
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That being so, there probably isn't much point in having an A1c test for a month or six weeks, by then, 75% or more of teh A1c value will be dominated by the new red cells produced.

All interesting stuff.

Mark