Bone marrow produces the many kinds of blood cells

DEAR DR. ROACH: You have mentioned diseases of the blood marrow in the column before, but what does the bone marrow actually do?

— T.S.B.

ANSWER: The main job of the bone marrow is to produce the different blood cells: red blood cells to carry oxygen; white blood cells to fight infection and cancers; and platelets to stop bleeding.

Diseases of the bone marrow can cause problems by making something abnormal (such as leukemia cells), but also by failing at its job and not making what it is supposed to.

Low red cell counts lead to anemia; low white cell counts increase risk of infection; and low platelet counts contribute to abnormal bleeding.

Bone marrow diseases sometimes can be treated directly, but often treatment involves replacing blood products, and possibly using growth factors to make the bone marrow work better.

DEAR DR. ROACH: Simple question: Why can’t I hear well when I am having a big yawn? Is this normal?

— J.C.A.

ANSWER: This is normal; in fact, it’s a universal finding with a yawn that hearing decreases (but doesn’t go away entirely).

This is because the Eustachian tube closes, and there is a pressure difference inside versus the outside of the eardrum, reducing the ability of the ear to transmit sound.

Interestingly, after a big yawn, hearing may be improved; when the Eustachian tube reopens after the jaw position changes, it can equalize the pressure and improve sound transmission.

DEAR DR. ROACH: I know women who have had double mastectomies in order to reduce the risk of cancer.

It seems extreme, but I guess it depends on the evaluation of risk.

Are prophylactic hysterectomies done for similar reasons? It used to be routinely done when a woman had passed her reproductive years.

I’m interested in your take on this. Will health insurance cover these types of surgeries, and if not, how expensive are they?

— S.B.

ANSWER: Prophylactic mastectomies — that is, surgery to remove the breasts in order to avert a breast cancer diagnosis — are a reasonable choice for some women at very high risk of breast cancer, especially those with a family history of breast cancer who have an identifiable genetic predisposition, such as one of the BRCA gene mutations.

This decision should be made carefully and in consultation with her doctors, usually an oncologist and a genetic counselor.

I have very little experience with this in my own patients, fortunately, but I understand that in the case of women with very high genetic risk, it usually is covered by insurance, if it is the consensus of the treating physicians and the patient that she should proceed.

Hysterectomy — the removal of a uterus — is not done routinely today, the way it was decades ago.

They are removed for disease, either benign or malignant.

However, the removal of both ovaries and Fallopian tubes, called a bilateral oophorectomy and salpingectomy, is performed in some women at high risk for ovarian cancer.

In fact, women with the BRCA mutations may consider both a prophylactic double mastectomy and a prophylactic bilateral oophorectomy and salpingectomy, since BRCA mutations increase risk of breast cancer and ovarian cancer (as well as other cancers).

The cost of surgery in the United States varies dramatically depending on where it is done, but in general it is very expensive.

READERS: Diabetes has become epidemic in North America. The booklet on it provides insight on its diagnosis and treatment. 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 request an order form of available health newsletters at 628 Virginia Dr., Orlando, FL 32803. Health newsletters may be ordered from www.rbmamall.com.