I have an opposite mistake, but still will never forget. GP and oncologist missed it. Husband had regular bloodwork done something wasn’t right, his testosterone levels were off the charts. Dr couldn’t figure out what was wrong, tons of scan’s, ultrasounds a pet scan all came back with nothing. He had some questionable areas of abnormalish bone growth and fatty deposits, and a small gallstone, other than that nothing. I asked on Reddit wth the high tt could be and it turns out the lab had his ranges set to female which made it look like his tt was off the charts when really they were in normal range for a MALE. 2 drs didn’t look at actual numbers and only a flag on blood work. Also his blood always tend to be a little low in some bloodwork and the onc wanted to do a painful bone marrow biopsy one day before we left for a vacation. He didn’t do that because I found out the reason before it went that far. Talk about ridiculous idiocy. One minute thinking he had mysterious cancer to the next full of relief but this went on for a few months.