kids with too hight hemoglobin?

Answer 1

Hold on, I'm just reading your thoughts.......
This is a question asking what causes a raised hemoglobin in children, right?
The biggest cause, by far, is dehydration, following an episode of vomiting, diarrhoea, or lack of fluid intake. Other causes of dehydration include kidney failure.
Other, uncommon, causes of raised hemoglobin include heart problems, some abnormal hemoglobins, essential polycythemia.

Pick one. If your child has been sick recently, I'd go for the dehydration, and get fluid into them a few sips at a time.