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Hi Julia,
Sorry for the delay in getting back to you....Thanksgiving and all of that. I think you are right in worrying about the possibility of oversuppression with your daughter. Her last numbers did seem to be very much on the low end---especially the 17-OHP and renin---so it was probably a good idea to reduce both the HC and florinef doses. When do you re-test?
The renin value you gave actually seemed REALLY low (though my son is not a salt-waster, so I have NO personal experience with this, just what I've seen in the literature.) According to a chart I found, the normal values listed for children your daughter's age is: Children 1-3 years old: 171-1115 NG/DL/HR, mean 535. Your daughter's last value of <20 NG/DL/HR is, obviously, way below that and I wonder if it could be contributing to her poor growth. Though it is generally well-accepted that, for those with elevated renin, florinef can aid growth by reducing hydrocortisone requirements, apparently too much florinef, resulting in decreased plasma renin activity, can also be detrimental to growth. I recently came across the following abstract and excerpt, which talk to this issue. I'll paste them in below.
As far as 17-OHP levels: I have seen a number of different ranges published as "acceptable" and hesitate to quote any of them here, if only because, over time, I (personally) feel that---because numbers can vary so much depending on time of day and whether tests were gotten before or after medication---it is almost meaningless to quote "acceptable" numbers without first qualifying the conditions under which those numbers were gotten. Suffice it to say, however, that your daughter's number of 9.7 NG/DL is low enough that, I think, most endos would probably agree that it means oversuppression, no matter which testing regimen they follow.
As far as timing of tests: I DO think it is important to factor in the conditions around which tests are taken. Since it is a fact that OHP levels fall dramatically after the morning dose of meds and that levels decrease naturally through the course of the day because of circadian rhythm, it only stands to reason that a number has to be evaluated in context, in order for it to be correctly interpreted. There seem to be two basic approaches to testing, one which approaches the issue by testing at the apex of control, i. e. when the medication is at its peak of absorption; the other which approaches the issue by testing at the nadir of control, i.e. once the medication has worn off. Testing after the morning meds would be an example of the first approach, while testing before the morning meds would be an example of the second approach. In a way, both seem to possess a certain logic, though---after thinking about it and from past personal experience with my son's bloodtests---I tend to think that---if a single blood test were your main indicator for control (vs. 24 hr. urine or blood spot testing)---the information gotten from approach #2 is probably more useful and accurate.
Since you've already made changes to your daughter's HC and florinef doses, though, I think it's important to keep her next tests at the same time as when you had them last, so you can compare "apples to apples." After a medication change, I think it is as important to determine the trend in a patient's levels (i.e. which way the numbers are moving), as it is to determine exactly where the numbers end up at, and changing too many variables, all at once, tends to cloudy the picture.
Hope this helps a bit to get your daughter's growth back on track. The good news is, using the formula for mid-parental height, I came up with (only) 5'-10" as a target height for her, rather 6'-0," so this should take a little bit of the pressure off (LOL!).
1: J Pediatr Endocrinol Metab 1998 Nov-Dec;11(6):733-7 |
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