How does Rivaroxaban affect the levels of protein S?

Question

Hello doctor,

At 33 years old, I experienced a pulmonary embolism two years ago, with a mild provoking factor identified as a combined oral contraceptive, despite only being on it for three weeks before the clotting event. Initially, I was prescribed Rivaroxaban 20 mg daily until I saw a hematologist. Recently, I consulted with a hematologist to investigate antiphospholipid antibodies due to a history of miscarriages and autoimmune disorders.

A full thrombophilia screen revealed a positive LA test and a low result for plasma-free protein S (32.0 IU/dL) measured by ELISA. Despite inquiring about protein S deficiency, my hematologist deemed it an "insignificant result," attributing it to the Rivaroxaban medication.

However, I am concerned, as no evidence in journal articles suggests that Rivaroxaban reduces free protein S levels. It may increase levels and mask a protein S deficiency. I seek a second opinion to ensure that an inherited or acquired protein S deficiency is not overlooked in my diagnosis and subsequent management.

Additionally, my medical history includes two previous miscarriages at five weeks and a family history of VTE and stroke on the maternal side. I am on Rivaroxaban 20 mg once daily, Amitriptyline 20 mg once daily, and vitamin supplements, including D3, methyl folate, and a preconception multivitamin.

Kindly guide.

Thank you.

Answer 1

Hi,

Welcome to icliniq.com.

I read your query and can understand your concern.

I want to ask if you are pregnant right now or not. Pregnancy lowers protein S levels. Secondly, it is important to note that Rivaroxaban is not recommended for antiphospholipid syndrome (APS) as it is not effective. APS is an autoimmune disorder in which the immune system mistakenly produces antibodies that target certain proteins in the blood.

Another crucial point is that to diagnose APS, you need to test positive for LA (lupus anticoagulant) 12 weeks apart, and other tests like anticardiolipin antibody are also required. There is a possibility of protein S deficiency, so it should be tested again, especially since you had a pulmonary embolism (a blockage in one of the arteries in the lungs, usually caused by a blood clot). Your weight seems higher than normal, which is another provoking factor. Please let me know your cholesterol levels.

I suggest quitting smoking if you do it, and also quitting alcohol if you consume it, to prevent all provoking factors. Stop taking oral contraceptive pills and keep an eye on your thrombophilia (characterized by an increased tendency to form blood clots) profile. These measures will help prevent further thrombosis (blood clots). I hope I made the point.

I suggest repeating LA and protein S testing, performing a full thrombophilia screen, and considering mutational analysis to confirm this deficiency.

I hope this helps.

Kindly revert so I can assist you further.