DEAR DR. ROACH: My husband was diagnosed with chronic lymphocytic leukemia (CLL) in 2010 and remained in stage 2 with no effects until 2022. In the interim, he was also diagnosed with atrial fibrillation and is taking Xarelto.

When the CLL came back in 2022, he was successfully treated with 10 infusions of rituximab. Due to a recent low platelet trend, he recently received another three rounds of rituximab. His platelets are now fluctuating between 110,000 and 66,000, which I find concerning, but the oncologist doesn’t seem to agree.

Do the blood thinners have anything to do with the low platelet count? The cardiologist recently reduced the Xarelto dosage from 80 mg to 40 mg. My husband was also recently hospitalized for sepsis.

This is complicated, and the doctors don’t appear to be consulting, which I find frustrating. I am sharing all reports among them. — N.P.

ANSWER: I am sorry about your husband’s cancer and hope his treatment remains effective. There are two different classes of medications to help people from having excess clotting. One class works on platelets, the blood-clotting cell that circulates in the blood. Medicines like aspirin and clopidogrel (Plavix) are used commonly. They don’t reduce the platelet number that decreases their functioning.

The second are the anticoagulants. These work by reducing the proteins that make blood clots, called clotting factors, and there’s an awful lot of these clotting factors that act in a complicated and highly regulated cascade. Warfarin (Coumadin) was the only anticoagulant for many years, which worked by reducing vitamin K (since it is needed to make blood-clotting factors).

Now there are several of these, such as rivaroxaban (Xarelto) and apixaban (Eliquis). These directly block the body’s ability to make blood-clotting factors such as Factor Xa or thrombin. They are called the direct oral anticoagulants (DOACs). Neither antiplatelet drugs nor DOACs actually thin the blood. Too-thick blood (“hyperviscosity syndrome”) is a rare and very dangerous condition that is most commonly caused by blood cancers.

People with many different kinds of leukemias, including CLL (like your husband’s), often have low platelet counts. However, the increased bleeding risk really starts at platelet levels below 50,000 and gets high when the level is below 20,000. Below 10,000 is when we can see spontaneous bleeding.

Since your husband hasn’t gotten into the worrisome range, his doctors aren’t concerned about bleeding (although they should have done a better job explaining this so that you wouldn’t have had to worry about this).

There is one type of anticoagulant that may sometimes affect platelet levels. Heparin, both unfractionated and low-molecular weight, can lead to a very dangerous drop of platelets called heparin-induced thrombocytopenia. (“Thrombocyte” is another name for platelet from the Greek root meaning “clot cell,” and the suffix “-penia” always means “too little of.” So, thrombocytopenia just means too few platelets.)

It is rare for DOACs to cause thrombocytopenia, but it can happen. In your husband’s case, it’s more likely that the leukemia or its treatment (rituximab) was the cause as these routinely cause low platelets.

As you say, the situation is complex. Sepsis (the body’s response to a severe infection) can also cause low platelets. For a person with leukemia, which has complex treatment regimens, it is imperative that his team communicates with each other, including (in his case) the cardiologist who is prescribing Xarelto.

Dr. Roach regrets that he is unable to answer individual letters, but will incorporate them in the column whenever possible. Readers may email questions to ToYourGoodHealth@med.cornell.edu. (c) 2025 North America Syndicate Inc. All Rights Reserved