Dear Dr. Roach: My insurance company won’t let me receive my testosterone injection unless I have a low testosterone level at 8 a.m. Does this make any sense? — T.B.

Answer: Although I am never fond of insurance companies making medical decisions, this does make sense from physiology. Cholesterol is made in the body, mostly in the liver and mostly at night between midnight and 8 a.m. (This is why people are often recommended to take statin drugs at night; although with long-acting statins like rosuvastatin, it isn’t as important.)

Since cholesterol is used to synthesize many hormones, including testosterone, testosterone levels peak in the early morning, usually between 7 a.m. and 10 a.m. A low level of testosterone at this time is very strong evidence that the testosterone level really is low and that replacement testosterone is needed.

People who work the night shift tend to get to their peak testosterone level shortly after waking, but the variation during the day is not as reliable as in people who are awake in the daytime. Peak levels are often lower than they are in daytime workers.

Testosterone replacement is best when given to men with symptoms of low testosterone and confirmed low testosterone levels at 8 a.m.

Dear Dr. Roach: In a recent column, a reader asked you what the proper dosage is for omega-3 fatty acids, and you omitted your answer. I would be interested to know. — SE

Answer: You’re right, and I’m sorry. The answer depends on the exact preparation and the reason why a person is taking them. For people wanting to increase their heart health, a dose of about 1 gram a day may produce a small benefit in reducing heart disease.

People with high triglycerides may be prescribed up to 4 grams a day of prescription-grade EPA and DFA, which has been shown to be of benefit in some high-risk people. The Food and Drug Administration recommends against supplements that are above 3 grams a day unless they are recommended by your clinician.

There is some evidence that having atrial fibrillation is more likely at higher doses, so doses above 3 grams per day should be reserved for people who are most likely to benefit from it.