Tests to Aid in the Diagnosis of Adult ITP

Transcript: Ivy Altomare, MD: You had spoken a little bit earlier about the differential diagnosis, trying to make the classification not only of the diagnosis, but is there a secondary cause of ITP [immune thrombocytopenic purpura], is it primary ITP? I want to stick with you and talk about how you make the diagnosis when you suspect ITP. What are the tests that you use? And what are the symptoms that you’re most likely to confuse between ITP and something else?

Terry B. Gernsheimer, MD: Let me first of all say we do not have a test to make the diagnosis of ITP. The only way to have a solid diagnosis is if the patient has responded to very direct treatment with either corticosteroids or with IVIg [intravenous immunoglobulin therapy]. That makes the diagnosis.

Ivy Altomare, MD: But it doesn’t differentiate between primary and secondary ITP.

Terry B. Gernsheimer, MD: No, it does not. And so I think it is very important to look for what we know is associated with these things, the viruses that I mentioned. I think everybody needs a thyroid test. And there are data to suggest that patients with a positive ANA [antinuclear antibody test] may do worse.

Ivy Altomare, MD: Oh.

Terry B. Gernsheimer, MD: Yes. And so I think it’s very important to be testing these things, to test a lupus anticoagulant and anticardiolipin antibodies. Pregnancy in a woman. If a young woman comes in to my office and she’s been referred, one of the first things I do is send a pregnancy test.

Ivy Altomare, MD: That’s a great point.

Terry B. Gernsheimer, MD: We have seen a lot of patients who present with thyroid disease, which is very important to treat. And frequently the platelet count will come back up.

Ivy Altomare, MD: Yes, I’ve seen that.

Terry B. Gernsheimer, MD: It’s really exciting when that happens.

Ivy Altomare, MD: Yes, the patient thinks you’re a genius.

Terry B. Gernsheimer, MD: Yes, exactly.

Ivy Altomare, MD: Rick, can I ask you, how often are you finding the need to do a bone marrow biopsy when you have a patient with thrombocytopenia, you’re not sure what’s going on?

Richard F. McDonough, MD: Good question. I’m not routinely using bone marrow biopsy, and so really looking at the other factors of the patient. Does the clinical picture fit? Does the time course make sense? In the peripheral smear, are there any other indicators of anything dysplastic that may make you think along those lines? So routinely no, I wouldn’t move toward bone marrow biopsy, particularly with younger patients, looking for classic presentation and particularly if they have other features, like you mentioned before, other immune diseases, things that make you think along those lines.

Ivy Altomare, MD: Yes, and then treating the underlying disease would be more the mainstay of treatment.

Ralph V. Boccia, MD: Can I ask the panel? Does anyone have an age at which they do a bone marrow aspirate and biopsy?

Ivy Altomare, MD: Good question.

Ralph V. Boccia, MD: Routinely, because of the potential for MDS [myelodysplastic syndrome], other than what you can see from the peripheral smear, per NCCN [National Comprehensive Cancer Network] guidelines, let’s say.

Amit Mehta, MD: My own approach, it’s interesting—and this differs a lot I think hematologist to hematologist—but my own practice is that if somebody fails at least 1 line of therapy, I generally will do a bone marrow aspirate and biopsy to rule out a secondary cause like CLL [chronic lymphocytic leukemia], lymphoma, etcetera, MDS. Also of course, like Rick was alluding to, looking for clues in the peripheral blood smear, in the complete blood count. Is it thrombocytopenia only or is it also bicytopenia, pancytopenia that would be obviously suggestive of something more going on than simply classic immune thrombocytopenia. So I don’t have an age cutoff per se. Definitely the older individual, historically, our training was that they have a high risk for concomitant MDS, and therefore perhaps more reason to look via biopsy. But even then, I personally don’t use a flat age cutoff to say, “Yes, they have immune thrombocytopenia, and I’m going to biopsy you via bone marrow biopsy off the bat;” it’s not my own approach.

Ivy Altomare, MD: I think that’s an excellent point. As we mentioned earlier, often you use steroids and then, if the platelet count improves, you believe that there’s an autoimmune process, which makes a lot of sense. But if a patient is very highly refractory, and they’re going quickly through first-line treatment, second-line treatment, then that is absolutely an indication to do a marrow, to see what’s going on.

Terry B. Gernsheimer, MD: Something very important that I think we’ve realized more recently is that some of these patients who we believe have ITP, do not have ITP.

Ivy Altomare, MD: Sure.

Terry B. Gernsheimer, MD: And they have an inherited thrombocytopenia, or they may have a marrow failure syndrome. So first of all, it’s so important to take a family history and see whether there’s any family history, not just of autoimmune disease in the background, but a thrombocytopenia.

Ivy Altomare, MD: Inherited thrombocytopenia, which we always have to remind ourselves is an existing thing.

Terry B. Gernsheimer, MD: But now we can do DNA sequencing and look for some of the marrow failure syndromes.

Ivy Altomare, MD: Wiskott-Aldrich, yes.

Terry B. Gernsheimer, MD: And RUNX1 [runt-related transcription factor 1]. The last thing you want to do is, and I’ve seen this, is a patient who’s been sent to me whose mother has had a splenectomy, and she’s now had her splenectomy and guess what, her platelet count is no better. We don’t want to see that anymore.

Ivy Altomare, MD: Right. Yes, I think the statistic is as high as 1 in 9 patients who are thought to have ITP actually have a hereditary syndrome.

Transcript Edited for Clarity