DEAR DR. ROACH: I watch several programs about zoos on TV. When they are dealing with animals, the weight/size of the animal always seems to come into play when medicating them. This applies whether it’s an initial tranquilizer dart, anesthesia, or follow-up medications like antibiotics and steroids.
Why then does my adult friend who weighs nearly 500 pounds get the same dose as an adult family member who weighs 110 pounds? Antibiotics, steroids, painkillers, etc., are all the same dosage for both. — C.S.
ANSWER: I have immense respect for veterinarians, who need to keep doses of different medications for different animals in their heads. Pediatricians dose most medications by weight, which varies dramatically between a newborn and an adolescent. But we adult-medicine doctors have it easier in this regard.
Still, the dosing given to an adult may vary considerably based on their size and age as well as their liver and kidney function. Many of the drugs you mention are both safe and effective across a wide range of dosages, so it may be appropriate to dose your 110-pound family member the same as your 500-pound friend. However, some antibiotics are dosed by body mass. Other drugs (many chemotherapy drugs) are dosed by the body surface area or by lean body mass.
When there isn’t much difference between an ineffective dose and a toxic one, the dose needs to be adjusted precisely. You mention anesthesia, which is also dosed in adults carefully based on their weight and multiple other factors when given intravenously. In some cases, doses can also be adjusted based on blood levels if a drug needs to be taken for a more prolonged time.
DEAR DR. ROACH: I am a 73-year-old diethylstilbestrol (DES) daughter. Mom was given DES to prevent a miscarriage when she was pregnant with me. My gynecologist says that I need to continue getting an annual Pap test, as there is a higher risk of cancer for DES daughters. The last two Pap tests were inconclusive, as the doctor was not able to get a good tissue sample. She says as we age, the lining of the uterus gets dryer and thinner.
She says I tested negative for sexually transmitted diseases (STDs). I don’t see the need for that information, as I have not been sexually active for at least seven years and have never tested positive for STD.
My question is: If she can no longer get a good tissue sample, even though I am a DES daughter, why should I continue with the Pap test? — K.M.
ANSWER: Women born from 1952-1954 are at the highest risk for having been exposed to DES, which was used to prevent miscarriages. However, it was used from 1947-1971, so women born during this time might still be a DES daughter.
The main health risk for an older DES daughter is cancer. Cervical cancer is a risk, and the standard Pap test is used to make a diagnosis. It is true that in older women, the thinning lining of the uterus makes getting a satisfactory cervical sample more difficult. However, DES daughters can also get an unusual cancer called clear cell cancer of the vagina.
Your gynecologist is getting vaginal swabs as well as cervical swabs to look for this condition, and she is exactly right that this should continue annually forever (as long as you are healthy enough to accept the treatment).
At this point, screening for sexually transmitted infections is no longer necessary for you.
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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 [email protected] or send mail to 628 Virginia Dr., Orlando, FL 32803.
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