DAT with ABID?

[whitemb]

Currently we perform a DAT with all of our ABID's as well as an auto control, and were wondering if the DAT is clinically significant?? We are looking at eliminating the DAT unless we have a positive auto control and/or pan agglutination in the panel cells. Could you please let me know what the practice is at your facility. Any information would be appreciated.

Thanks,

Barbara

[Malcolm Needs ☆]

Currently we perform a DAT with all of our ABID's as well as an auto control, and were wondering if the DAT is clinically significant?? We are looking at eliminating the DAT unless we have a positive auto control and/or pan agglutination in the panel cells. Could you please let me know what the practice is at your facility. Any information would be appreciated.

Thanks,

Barbara

We perform a DAT if there is a pan-agglutinin present, even if the auto is negative, or if the patient has recently been transfused (but then we are a Reference Laboratory, so we know that most of our samples are out-of-the ordinary).

If we have a reason, we may also perform an eluate, even if the DAT is negative.

All that having been said, I wouldn't do a DAT on all panels in a hospital laboratory situation (and never did when I worked in a hospital laboratory).

:):)

[AMcCord]

We require an auto with ID panels, but only do the DAT if indicated. Panagglutination, positive auto, funky looking panel results, specifically requested by physician, and history suspicious for hemolysis covers a lot of the 'indicated terrirory'.

[tbostock]

We do an autocontrol in gel with each ABID, if positive, then we do the DAT.

[BSIPHERD]

Currently we perform a DAT with all of our ABID's as well as an auto control, and were wondering if the DAT is clinically significant?? We are looking at eliminating the DAT unless we have a positive auto control and/or pan agglutination in the panel cells. Could you please let me know what the practice is at your facility. Any information would be appreciated.

Thanks,

Barbara

We do a DAT with a panel rather than an auto control. If all cells are positive on the panel and the DAT is negative, then we do an auto control, but this is very rare.

Belva in Lincoln

[David Saikin]

Auto ct with panel; DAT if positive. Formal reference places usually do a DAT too (and Rh phenotype) on all referred specimens. Makes a lot of sense, but most of my referrals do not care to have (or should I say "pay" for) that complete workup.

[adiescast]

We do a DAT with solid phase panels, auto control with tube panels (the auto is a pain in the neck for solid phase). We don't do both on a routine basis (one or the other). If the tube auto control is positive, we follow up with a DAT.

[Eagle Eye]

Gel user--we do AC with panel. If AC is positive then we do DAT by tube and if DAT positive then prepare and test an eluate.

[whitemb]

Thank you for your responses. For those of you who perform the autocontrol with the panel and only do a DAT if indicated; what documentation did you use to support this practice? In order for us to change our prodcedure, we are required to present such documentation.

[Likewine99]

We are the same as tbostock

[rravkin@aol.com]

Currently we perform a DAT with all of our ABID's as well as an auto control, and were wondering if the DAT is clinically significant?? We are looking at eliminating the DAT unless we have a positive auto control and/or pan agglutination in the panel cells. Could you please let me know what the practice is at your facility. Any information would be appreciated.

Thanks,

Barbara

WhiteMB,

The introduction of an IgG Ab into the circulation is represented by an "S" curve plot of "Ab concentration in the plasma" (X axis) verses "Time" (Y axis). One of the unique characteristics of an "S" curve is that there is an initial "Lag Phase" (representing the start of the curve). This lag phase occurs here because when the IgG Ab makes it's initail appearance in the circulation it bonds to accessible Ag sites thereby taking the IgG out of the plasma and away from our detection capability in the BB. And we all know that when we collect a blood specimen this specimen represents a single snap shot of the circulating whole blood at the time of collection (just like a Polaroid). The DAT detects bound IgG only; the Auto Control "may" detect bound IgG and/or anything else bound to the RBC's. I worked at a facility that did not practice running Auto Controls with Panels; they said that they did not want to open a can of warms; my current employer wants to open that can of warms always. How often do we see a positive DAT and a negative Panel? Rarely in the hospital setting but maybe Malcolm sees it more often in the Reference lab (Lucky you Malcolm). But make no mistake that the positive DAT is very clinically significant and if I had the choice of which test to run in addition to the Panel I would chose the DAT because it can detect the "Lag Phase" were the Auto Control may not; and thereby give us a more complete picture of where along the immune response cycle this patient may be. In reality these are difficult choices indeed because there is a weighing of cost to patient benefit. I'm a bleeding heart, so I would always side with the patient benefit over cost. When we went to plastic flatwhere at some of our favorit eateries we will never go back do to cost structure. I always think it's better to structure cost around patient benefit solely or otherwise our work, and medical, advances are meaningless.

Sorry for the rag. I hope this helps a little.

[Deny Morlino]

Nice explaination! With your permission may I "borrow" it for student education / tech refresher?

[rravkin@aol.com]

Nice explaination! With your permission may I "borrow" it for student education / tech refresher?

Absolutely Deny.

[Yanxia]

rravkin@aol.com, you say the Auto Control "may" detect bound IgG and/or anything else bound to the RBC's . Can I understand it as something not antibies or not clinical significance bound to the RBCs which can disturb the test? Thanks !

[Yanxia]

We perform a DAT if there is a pan-agglutinin present, even if the auto is negative, or if the patient has recently been transfused (but then we are a Reference Laboratory, so we know that most of our samples are out-of-the ordinary).

If we have a reason, we may also perform an eluate, even if the DAT is negative.

All that having been said, I wouldn't do a DAT on all panels in a hospital laboratory situation (and never did when I worked in a hospital laboratory).

:):)

Malcolm, would you please tell me in what circumstance the autocontrol is neg and DAT is pos? Thanks!

[Malcolm Needs ☆]

Malcolm, would you please tell me in what circumstance the autocontrol is neg and DAT is pos? Thanks!

Hi shily,

I really cannot explain it any better than the fantastic explanation given by rravkin@aol.com in post 11 of this thread.

Malcolm

:redface::redface:

[Liz]

WhiteMB,

The introduction of an IgG Ab into the circulation is represented by an "S" curve plot of "Ab concentration in the plasma" (X axis) verses "Time" (Y axis). One of the unique characteristics of an "S" curve is that there is an initial "Lag Phase" (representing the start of the curve). This lag phase occurs here because when the IgG Ab makes it's initail appearance in the circulation it bonds to accessible Ag sites thereby taking the IgG out of the plasma and away from our detection capability in the BB. And we all know that when we collect a blood specimen this specimen represents a single snap shot of the circulating whole blood at the time of collection (just like a Polaroid). The DAT detects bound IgG only; the Auto Control "may" detect bound IgG and/or anything else bound to the RBC's. I worked at a facility that did not practice running Auto Controls with Panels; they said that they did not want to open a can of warms; my current employer wants to open that can of warms always. How often do we see a positive DAT and a negative Panel? Rarely in the hospital setting but maybe Malcolm sees it more often in the Reference lab (Lucky you Malcolm). But make no mistake that the positive DAT is very clinically significant and if I had the choice of which test to run in addition to the Panel I would chose the DAT because it can detect the "Lag Phase" were the Auto Control may not; and thereby give us a more complete picture of where along the immune response cycle this patient may be. In reality these are difficult choices indeed because there is a weighing of cost to patient benefit. I'm a bleeding heart, so I would always side with the patient benefit over cost. When we went to plastic flatwhere at some of our favorit eateries we will never go back do to cost structure. I always think it's better to structure cost around patient benefit solely or otherwise our work, and medical, advances are meaningless.

Sorry for the rag. I hope this helps a little.

Very well explained. Thanks.

I ask my students about the AC, DAT and Ab Screen and I ask them to consider allo Abs or auto Abs or both and in each situation what would be the result of each of these 3 tests. Try it, it's fun for them and us.

Liz

[Liz]

Malcolm, would you please tell me in what circumstance the autocontrol is neg and DAT is pos? Thanks!

As was said by those before me in this thread: if all the Abs have senstized the cells you will have a negative AC and a positive DAT.

You may get a negative DAT with a negative AC if the senstized cells have hemolised or were taken up by the RES. These Abs may be allos if recently transfused, or autos.

Note: a Negative DAT also occurs if you have a low number of Abs sensitizing the cells; and for completion (in hope of not being corrected by Malcolm :D:D:D) if the Ig is not an IgG or C3b and you are using anti-IgG and anti-C3b.

[i may have to stand corrected by my teachers in this thread ]

Hope this helps.

Liz

[Malcolm Needs ☆]

As was said by those before me in this thread: if all the Abs have senstized the cells you will have a negative AC and a positive DAT.

You may get a negative DAT with a negative AC if the senstized cells have hemolised or were taken up by the RES. These Abs may be allos if recently transfused, or autos.

Note: a Negative DAT also occurs if you have a low number of Abs sensitizing the cells; and for completion (in hope of not being corrected by Malcolm :D:D:D) if the Ig is not an IgG or C3b and you are using anti-IgG and anti-C3b.

[i may have to stand corrected by my teachers in this thread ]

Hope this helps.

Liz

10 out of 10!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!

:D:D:D:D

[Liz]

Malcolm,

Great!! Thanks!!

(This is a moral booster for me, I never get a pat on the back at work, thank you!!)

Liz :)

[Yanxia]

As was said by those before me in this thread: if all the Abs have senstized the cells you will have a negative AC and a positive DAT.

Liz

Thanks, Liz. I think I understand it. You mean do the AC use patient eluated cells add patient serum and my previous meaning is use patient untreated cells add serum, this is the different. Thank you again!

[Yanxia]

I will do autocontrol with panel first, if autocontrol is pos then DAT.

I think there is a kind of case that the antibodies bind on the cells if below our detect level so the DAT is neg, and in the autocontrol it will be pos because it can bind more antibodies during the incubation and /or liss, peg et al. And autocontrol is a control it can tell us if there is something disturb the panel test just as mailto:rravkin@aol.com mentioned.

So, I think DAT can't displace autocontrol .

Edited July 19, 2010 by shily
spelling error

[Malcolm Needs ☆]

I will do autocontrol with panel first, if autocontrol is pos then DAT.

I think there is a kind of case that the antibodies bind on the cells if below our detect level so the DAT is neg, and in the autocontrol it will be pos because it can bind more antibodies during the incubation and /or liss, peg et al. And autocontrol is a control it can tell us if there is something disturb the panel test just as mailto:rravkin@aol.com mentioned.

So, I think DAT can't displace autocontrol .

You are correct shily in that the DAT cannot displace the auto-control, but there is many a time when it is equally true to say that the auto-control cannot displace the DAT.

:):)

[Liz]

Thanks, Liz. I think I understand it. You mean do the AC use patient eluated cells add patient serum and my previous meaning is use patient untreated cells add serum, this is the different. Thank you again!

Shily,

I do not elute the patient's cells when I perform the auto-control.

Liz

[Malcolm Needs ☆]

and for completion if the Ig is not an IgG or C3b and you are using anti-IgG and anti-C3b.

Liz

Just by sheer and utter coincidence, we had a myeloma case in yesterday with a positive auto, but a DAT that was positive with monospecific anti-IgA reagent only, and so would, to all intents and purposes, have had a negative DAT if we had only used "conventional" anti-IgG and anti-C3d reagents; it was negative with monospecific anti-IgG, anti-IgM, anti-C3c and anti-C3d reagents.

These findings are quite rare, but not as rare as one would tend to think.

:):)