DEAR DR. ROACH: I have worked in a loud facility for 35 years and have always worn protection and had my hearing tested annually. Several years ago, I had a threshold shift (a loss in my hearing range), and the plant nurse sent me to a hearing specialist. He said that my hearing loss is not due to noise exposure. I asked how he could tell, but I didn’t get a satisfactory answer. I later asked my primary care physician, and he didn’t know.

How do you determine from the result of a test whether hearing loss is caused by noise exposure or other factors, such as illness or injury? Would a hearing aid be effective? — J.G.

ANSWER: A comprehensive exam and hearing testing can show whether the hearing loss is likely due to loud noise exposure, based on the pattern of hearing loss across different frequencies. However, I don’t think that there is 100 percent certainty about making or excluding noise exposure as the cause of the hearing loss from the pattern.

I would think that an independent evaluation, by a certified audiologist and your own ENT doctor, might give you additional information, including a discussion about how much benefit you might get from a hearing aid. The Hearing Loss Association of America (on the Web at www.hearingloss.org) can provide you some support and guidance through this process.

DEAR DR. ROACH: You have written many articles about high blood pressure, but I want to know about low blood pressure. What is normal? What is low, and what is dangerously low? I have a heart issue for which I take medication. I want to know if my blood pressure is too low. — Anon.

ANSWER: Among young adults, only 5 percent of men will have a blood pressure below 110/60 or so, and for young women, it’s 90/46. Blood pressure tends to go up with age, so low blood pressure numbers are higher for older adults.

For people with healthy hearts, the only time we worry about low blood pressure is if there are symptoms, and the most common symptoms are lightheadedness and fainting.

In people with congestive heart failure, low blood pressure usually is not concerning in itself, but because it might indicate that the heart is getting weaker. However, many of the medications used for CHF reduce blood pressure, which can even limit the amount of medication that can be used. In people with blockages in their arteries, too low a blood pressure can cause inadequate blood flow to parts of the heart and cause angina symptoms.

The blood pressure is dangerously low when a disease process is causing the low blood pressure. In extreme cases, low blood pressure is one of the most dangerous signs of shock. But in general, for healthy people, low blood pressures are not worrisome.

READERS: Bone health is an issue that is important to all of us. The osteoporosis pamphlet furnishes details on how to prevent this universal condition. Readers can obtain a copy by writing: Dr. Roach — No. 1104, Box 536475, Orlando, FL 32853-6475. Enclose a check or money order (no cash) for $4.75 U.S./$6 Can. with the recipient’s printed name address. Please allow four weeks for delivery.

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 P.O. Box 536475, Orlando, FL 32853-6475. Health newsletters may be ordered from www.rbmamall.com.