ANSWER: The reason I don’t recommend a urinalysis (and, in fact, most blood tests) is that they are more likely to cause harm (from evaluating and possibly treating a false-positive result) than they are to cause good (by finding an unsuspected condition at a time when it can be more easily treated).

This is very difficult to explain, and I often see people in my practice and who write in with just the attitude you have, and I find it understandable. Part of it is the fault of doctors and of the media, who often say that if we had found out sooner, the outcome could have been better. That is often the case when someone has symptoms of a potentially serious condition, but rarely is the case when someone has no symptoms at all and isn’t in a high-risk group.

I can understand why, given your sister’s experience, you are inclined to want this test. Experiences of people close to us always are powerful. But I also know of a case of a man who had a nonrecommended screening test, which led to a biopsy, which led to an infection of the spinal cord, which ultimately left him a paraplegic. Severely bad outcomes like that are rare, but overall it is more likely that most tests done in asymptomatic people, where there isn’t any reason to suspect an underlying condition, will lead to unnecessary testing, pain, anxiety and expense than they are to lead to a good outcome.

There are some exceptions. Checking blood pressure and cholesterol periodically is a good idea, since high blood pressure and high cholesterol can be treated early and reduce risk for heart attack and stroke. Some cancer screening tests, such as colonoscopies and Pap smears, are appropriate at particular ages. Because doing testing on asymptomatic people requires a high level of proof that they cause more benefit than harm, several groups, especially the U.S. Preventive Services Task Force, regularly evaluate the evidence on what screening tests are appropriate for the general population as well as for high-risk groups. Routine urinalysis is recommended for healthy pregnant women but not healthy men or nonpregnant women.

DEAR DR. ROACH: I have recently been diagnosed with an eye disease called macular telangiectasia Type II. I have seen two different specialists; both have told me that there is no known cause or treatment. I am 53 years old and already have lost the ability to read in my right eye. Is there any other information you may have on this disease? — W.L.

ANSWER: Macular telangiectasia is a very uncommon condition, thought to be at least partially due to vascular disease, since diabetes and hypertension are known risk factors. Some people are treated with ranibizumab (Lucentis) or bevacizumab (Avastin) injections in the eye. The National Institutes of Health is sponsoring a worldwide study to better understand this disease. Unfortunately, treatments aren’t successful in some people.

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.