Dear Dr. Donohue • I am a 78-year-old male and have blood tests and physicals every year. In 2001, my cholesterol was 225 mg. Every year it was lower, until this year it was 94. My LDL was 29 , and my triglycerides 36. My weight stays between 138 and 144 pounds. I am 5 feet 6 inches tall. My appetite is good. I am not nor have I ever been on a low-cholesterol diet. Should I be concerned? — B.S.

Answer • I have never seen such low values. Normal cholesterol should be less than 200 mg. The LDL cholesterol (bad cholesterol) optimum level depends on associated risks, like having had a heart attack, in which case it should be less than 70, or less than 100 if other factors for heart disease are present. Some experts advocate even lower LDL numbers. They maintain that a value of 40 affords greater protection against having a heart attack.

A normal triglyceride reading is less than 150 mg.

Very low readings for cholesterol are seen with advanced cancer. You are not likely to have had advanced cancer for nine years without any symptoms. A digestive tract that doesn't absorb nutrients is another cause of low readings. Again, other symptoms ought to be present, things like diarrhea and weight loss.

If I were your doctor, I would give you two choices. One is to be retested in a matter of months, maybe three. Or I would send you to an expert in lipid disorders (lipids are cholesterol and triglycerides). Such experts are found in large medical centers or at medical centers connected with a medical school. I checked your address. You are not far from such institutions.

I am baffled. I take it you're not on any cholesterol-lowering medicines.

Dear Dr. Donohue • I have a 19-year-old grandson. To look at him, you would say he is 14. His diet consists of chocolate-chip cookies for breakfast. For lunch he might have an ice cream on a stick. He eats mostly chicken for dinner with white rice. On Saturdays it is pizza, and on Sundays, a piece of steak with white rice. He drinks only water and decaf iced tea.

The same menu is repeated every week since his mom died eight years ago. He has never eaten a piece of fruit or any vegetables. He has never drunk any milk or juice. On the other side, he has never eaten any candy, soda pop or cakes. He is 5 feet 9 inches tall and weighs 120 or less. He has Asperger's disorder. — D.A.

Answer • This young man's diet is alarmingly bizarre, and his weight is alarmingly low. He's not getting the nutrition he needs.

It's most likely that psychological problems are contributing to his choice of diet. His Asperger's could be involved. Who made this diagnosis for him? If it was recent, I would take him to that person and ask for help. Or get him to a doctor and ask the doctor, after his exam, for a referral to a mental health professional.

Write Dr. Donohue at P.O. Box 536475, Orlando, Fla. 32853-6475.