There is a study done about this-low cortisol levels being associated with nausea and vomiting- which I feel links to why some CAH kid’s feel nauseous from time to time.  As cortisol levels are more likely to fall below acceptable ranges in our kids--even within a 24 hour period and at sometimes when doses are being outgrown--, I suspect that may be why some times they do feel nauseous.  The study was done in relation to Chemotherapy treatment which can affect the HPA (Hypothalmic-Pituitary-Adrenal) Axis and which effects similar nausea and vomiting.  You can read more at the URL below but here is a snippet of the text on that page.

"Taken  together, these studies indicate that "low" levels of cortisol are associated with an increased incidence and magnitude of nausea and vomiting and perhaps account for the efficacy of endogenous cortisol as an anti-emetic. The site and mechanism of action is not known, but among those suggested (Seymour, 1993) are:
Reduction in cerebral edema and blood brain barrier permeability;

Reduction in prostanoid turnover;

Increased endorphin release;

Reduction in 5-HT metabolism; and

Modulation of neuronal membrane ion permeability.
There is also evidence that chemotherapy drugs may directly or indirectly influence the activity of the hypothalamic-pituitary-adrenal (HPA) axis. Figure 3.2 characterizes the temporal changes in blood cortisol concentrations in 23 women with carcinoma of the ovary treated with platinum-based chemotherapy and administered dexamethasone as part of antiemetic prophylaxis (Morrow et al., 2000). A significantly reduced level of serum cortisol was present immediately following the infusion of either cisplatin or carboplatin, suggesting that the effect is present by the end of the chemotherapy administration.

The serum cortisol levels for both Treatment 1 and 2 days were significantly lower for the first four hours following chemotherapy than on the non-treatment baseline day. Since the reduction in cortisol was seen only in the presence of the cytotoxic drug, it is likely that the effect is "direct" and does not involve any overt psychological or circadian mechanism."

You can read more by going to:

http://symptomresearch.nih.gov/Chapter_11/sec3/cgms3pg3.htm

 

I really feel it is a lot to do with the lowered cortisol levels.  After all, when they are low in illness the first symptom we see in the kids is nausea and vomiting.  I think  it also affects things like sense of smell or aversion to certain smells and tastes also, rather like when a Pregnant women has the morning sickness as as been discussed in the past here.  After all pregnancy is just hormone levels fluctuating dramatically--and the possibility for this to happen in our kids is there.  Maybe at certain times of the day they have lower levels and less tolerance to certain smells and nausea triggering events?

Regards

Anne-Marie