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: My hands and fingers (especially my left hand) are numb with a pins-and-needles sensation. It is very painful, especially in the morning, but it does happen during the day. Also, my fingers lock, and I have to pry them open. Why does all this happen? My middle finger on my left hand is always tender and numb.

• B.Z.

ANSWER: I think you have two separate problems. The first is a neuropathy, which just means that something is wrong with one of the nerves. Since the middle finger is numb, it’s your median nerve that is affected, and the most common cause is carpal tunnel syndrome. Having more pain in the morning is common since many people sleep in a position that causes pressure in the carpal tunnel, which means more damage to the nerve. Your regular doctor or a hand specialist can diagnose this more certainly.

Having to pry open your fingers could be due to weakness but are more likely to be trigger fingers. Again, your regular doctor can make this diagnosis, but a hand specialist is the right person to go for treatment, which might be physical therapy or an injection. If you really do have weakness rather than trigger fingers, this is a reason to get your carpal tunnel syndrome treated right away.

ToYourGoodHealth@med.cornell.edu.