Unless I am mistaken it sounds like your son has the 21- hydroxylase  deficiency CAH (sometimes called CYP21 defect and sometimes written as 21 -OHD)  which is what most of us have. This relates to which enzyme is missing in the steroid pathway. About 95 % of CAH people have this type of enzyme deficiency.

Some of the other types of CAH - like....3 beta hydroxysteroid dehydrogenase deficiency, 11 beta hydroxylase, 17 alpha hydroxylase and lipoid are much more rare.

So most times when people are talking on this board they are talking CYP21 enzyme deficiency, although there are some here with the other forms as well.

As to the ’hypo’ - do you mean ’hyper’ as in hyperplasia which refers to the adrenal gland becoming larger (overgrowth) to try to make more cortisol. This is where the term Congenital Adrenal Hyperplasia comes from.

The next categories are to do with the severity of the CAH a particular individual has, regardless of the enzyme deficiency.

OK so there is Classical CAH which is comprised of two levels

1). Salt Wasting (SW) - apart from the inability to make cortisol the SW person cannot retain salt because of severe aldosterone deficiency and always needs to take Florinef. 

2). Simple Virilising (SV) - also has an inability to make adequate cortisol but has some ability to retain enough salt. May need to take Florinef particularly in childhood.

Then there is Non-Classical CAH where the enzyme deficiency is usually much milder. However it can still be diagnosed in childhood but more often in adolescence or adulthood.

CAH terminology is daunting at first but with time you will become familiar with it. A good way to learn fast is to make sure you get a copy of your child’s lab reports each time bloods are taken.  This way you will learn the names of the tests performed and the levels. It really is a whole new learning experience but by learning as much as you can early on, you can be the best advocate for your child in the future in regard to this condition.