Blood Disorders

Is there any way to prevent deep-vein thrombosis during travel?

DEAR DOCTOR K: A friend of mine recently developed a blood clot in his leg after a long flight. I travel a lot for work, so this has me worried. Is there any way to prevent this type of thing?

DEAR READER: A blood clot that forms deep inside a leg vein, known as deep-vein thrombosis (DVT), can cause pain, swelling and redness in the affected limb. But the real threat happens if the clot breaks off and travels to the lungs. Known as a pulmonary embolism, this can lead to sudden death. (I've put an illustration of this process on my website,

What does it mean if my hemoglobin is low?

DEAR DOCTOR K: I'm a 31-year-old woman, and I try to donate blood every couple of months, but the last time I tried, I was turned away because my hemoglobin was too low. What does that mean? And what can I do about it?

DEAR READER: That's terrific that you are a regular blood donor. The American Red Cross says that one pint of blood -- roughly the amount collected during a donation -- can treat an average of three people who need blood. And that treatment can save lives.

Is it safe for me to fly again if I’ve already had a deep-vein thrombosis (DVT) from air travel?

DEAR DOCTOR K: Last year I developed deep vein thrombosis (DVT) -- blood clots in my legs -- during a long international flight. One of the clots got loose and went to my lungs. I'm fine now and am off all medications. Is it safe for me to fly again?

DEAR READER: Yes, you can fly again if you take some precautions. Before I describe them, though, a little background information is in order.

Which drugs have interactions with warfarin?

DEAR DOCTOR K: I recently had a stent placed and am now taking warfarin. Do I need to worry about drug interactions?

DEAR READER: You (and your doctor) need to be careful about drug interactions. Many other drugs have dangerous interactions with warfarin (Coumadin). Warfarin is an anticoagulant, or blood thinner. It decreases your blood's ability to clot.

What is pernicious anemia and how is it treated?

DEAR DOCTOR K: For years, my pernicious anemia was misdiagnosed as depression. Now that I have an accurate diagnosis, I'd like to learn more about my condition.

DEAR READER: The cause and treatment of pernicious anemia were discovered more than 80 years ago. Unfortunately, even today there still are people like you for whom diagnosis and treatment have been delayed. That's because, as I explain below, it can be a tricky condition to diagnose.