DEAR DR. ROACH: I’m an 88-year-old woman whose platelets went into the 500,000 range. I was sent to a hematologist/oncologist, who said it was a bone marrow disease. I was put on hydroxyurea 500 mg. A couple of months later, a blood test showed enlarged red blood cells, which I understand is from the hydroxyurea, but my doctor says it also prevents blood clots and strokes. However, in July I got a blood clot in my leg, and I am now on Xarelto for life. My question is if you think I could get additional clots from hydroxyurea, and if this is the best treatment. — G.R.

ANSWER: You have a condition called essential thrombocythemia. “Essential” means we don’t know what causes it; while “thrombo-” is for “clot”; “cyt” is for “cell”; and “hemia” is for the blood, so it’s too many clotting cells (platelets) in the blood. It is now known that ET is almost always related to a genetic mutation, especially one called JAK2.

Some people get diagnosed because of symptoms such as headaches, or due to complications, especially clotting or bleeding. However, many are diagnosed just because their routine blood test shows a high platelet level. The goals of treatment are to relieve symptoms, if any, and to prevent complications.

Hydroxyurea dramatically reduces risk of blood clots, from 24 percent to less than 4 percent in people at high risk, like you (over 60 and with a history of clot). Most experts would use an anticoagulant like rivaroxaban (Xarelto) in someone who had a clot despite taking hydroxyurea. It is very effective at preventing future clots. As best I can tell, you are on the treatment that most experts would recommend.

DEAR DR. ROACH: What causes (and what can cure) bruxism? I have had the problem for 12 years and have sought help from my dentist, doctor and others. Each has his or her own theory about the cause — but no one has a cure. Every night, I wear a “splint” (night guard), as I have cracked a few teeth in the past, before we knew bruxism was one of my problems. — L.D.

ANSWER: Bruxism (jaw clenching and grinding at night) seems to be an exaggeration of a normal response to arousal from sleep. They come from uncontrollable impulses from part of the brain, the brainstem, involved in very basic maintenance of blood pressure and the motor system. Although researchers have tried interventions to improving sleep quality, they have been unable to show improvement in the grinding behavior itself. Treatment is then primarily aimed at preventing damage to the teeth, jaw, muscles and joints involved, and the use of an oral device, such as your occlusive night guard, improves sleep quality and reduces damage to teeth, at least anecdotally.

DR. ROACH WRITES: A recent column on statin treatment for high cholesterol included a comment on adopting a mostly plant-based diet to reduce cholesterol and reduce heart risk, and several readers asked if I had a specific diet in mind.

I feel strongly that no one diet is right for every person, so I resist giving exact advice on diet. By “mostly plant based” I mean that the majority of someone’s nutrition should come from vegetables, fruits, legumes, whole grains and nuts. Fish is optional for people who want that. Meats should form a smaller part of the diet than most people take in, while processed grains and simple sugars should be taken in very sparingly. There are many good places for getting good diet information, and a dietician nutritionist is a valuable consultant for people with more specific questions.

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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 or send mail to 628 Virginia Dr., Orlando, FL 32803.

Dr. Roach