Initial Blood Counts predict response to IST and survival?

[JodyW]

I was hoping someone could clarify something for me.

THere is a slide titled "Initial Blood Counts predict response to immunosuppression and Survival" in a presentation given by Dr, P Scheinberg. from NIH. In the slide I think slide #34 it has a graph showing ARC >25000 has a better response rate to IST then ARC <25000 at time of treatment. When I looked at my son's Assessment from the Dr at time of diagnosis it states- "With a Hemoglovin of 3 one would expect a more brisk reticulocytosis and his was only 1.4%, which is concerning for inadequate marrow response."

MY question is how does one convert 1.4% to the 25000 number used in the presentation? I have been trying to figure this out all day. Im sure someone much smarter on here already has the answer, or can tell me what im missing. Appreciate the help.

[Marlene]

Try this......

http://www.mdcalc.com/absolute-reticulocyte-count-index

http://www.fpnotebook.com/hemeonc/lab/RtclcytCnt.htm

I think the first one is for a different measurement. I tried the second one but the decimal point comes out different than John's actual results. Hmmmm.

[Greg H]

Marlene & Jody,

I think the first one is for the reticulocyte index, even though that's not what the webpage says.

One of the labs that I us never reports absolute reticulocytes, but instead reports the percentage. So I calculate it myself like this:

RBC X %Reticulocyte X 10 = Absolute reticulocyte

My last labs were RBC 2.56 & Reticulocyte percentage 2.6%

2.56 X 2.6 = 6.7
6.7 X 10 = 67 Absolute reticulocyte count.

This is the same formula in Marlene's second reference; they just call RBCs "erythrocytes."

This absolute reticulocyte count is actually in thousands of units. So my 67 is really 67,000. Scheinberg is using this number.

So, Jody, if we have your son's RBC count, we can figure his absolute reticulocyte number.

Take care!

Greg

[Marlene]

Thanks Greg. It's still off just a bit so my guess it's a rounding error.

[Greg H]

Hey Marlene!

I haven't gone back to check the equation against those CBCs for which I actually have absolute retic reported, but I'm not surprised it is a bit off. I'm not really sure whether the labs that report absolute retic are calculating the number from the percentage or developing the percentage from a count.

Take care!

Greg

[JodyW]

Thanks for the explanations. I think I understand this now.. Never understood the conversion to thousands and it was definalty confusing things for me. I am working on getting his RBC prior to the start of ATG.. Thanks again.