Inferior Petrosal Sinus Sampling (IPSS) is another interesting test, sometimes ordered by endocrinologists, sometimes ordered by neurosurgeon's. It is preformed by experienced interventional radiologists, generally at a large hospital.
If you've ever heard of a cardiac catheter, where they feed a tube or wire up from your femoral artery into your heart...that's similar to what this test is. Except they thread two up towards either side of your pituitary. "Inferior Petrosal Sinus" is the location of the sampling area. When everything is in place, IV's, catheters, etc...they inject you with medication that is meant to force an ACTH producing tumor to produce high levels of ACTH. At timed intervals, they then draw blood samples from your left and right sides at various points (including just below the pituitary). All this data is put into a table, which then can show whether your levels were highest from near the pituitary (which would point to a pituitary tumor) or another area (which would point to an ectopic tumor somewhere else in the body). It *can* also help identify which side of the body or pituitary it is coming from, but at least with pituitary sources, it is only about as accurate as a coin toss in pinpointing sides.
The test can be useful, but really, you want a surgeon that will explore your entire gland to look for tumor tissue anyway, not only rely on a test with poor statistical accuracy. When they explore the gland they make little slices through the entire surface of the pituitary, which generally heals back together well, looking for pockets of tumor tissue (which we jokingly call "fileting"). Many times tumors of florid Cushing's patients are nicely encapsulated circles, but often, cyclic or eptopic patients' tumors are gooey (getting destroyed by suction with no tumor tissue for pathology testing), or oddly shaped (think of dumbbells, octopus tentacles, a thin flat tumor spreading the entire bottom of the gland, multiple tumors, etc). If doctor's aren't experienced in these kinds of tumors and are only looking for a perfect tumor and only looking in one spot, they may miss the tumor entirely, spread gooey tissue around (YIKES!), or miss parts of the tumor...leading to a failed surgery or a brief remission followed by a recurrence of Cushing's Disease, which is already hard to cure. A recurrence may be unavoidable, but you certainly want the best chance possible.
I also strongly encourage you not to settle for the nearest neurosurgeon --what happens in surgery can make all the difference in your quality of life for years to come. Study it out, ask informed questions, talk to their past patients, and make sure you are comfortable with their experience (of removing Cushing's-specific tumors) and their methodology before letting them into your head. It is your head. You have to live with the results.
Sunday, April 26, 2015
Saturday, April 25, 2015
Testing for Cushing's, Dex
There are actually two types of Dexamethasone Suppression Tests (Dex) used in diagnosing Cushing's, a high dose and a low dose test. There are some differences in procedure, timing, and...you guessed it...dosage. I'm not going to go in-depth on the procedures of either, but more give a brief overview of what the test is, what they're looking for, and it's downfalls.
These tests are kind of the opposite of a "stim" test in that it isn't meant to stimulate production, but to suppress it. The point of these tests is to give your body sufficient steroids (Dexamethasone) so that your pituitary's own feedback will stop it's production of ACTH. In a healthy HPA axis, your body recognizes there is already enough in your system, and thus doesn't produce more. They give the medication a set number of hours for your pituitary to respond, and then check your cortisol levels to see how much your cortisol has suppressed (or dropped).
Many forms of steroid replacement medication will show up as "cortisol" on lab tests, but in the testing used here, Dex does not. This makes it a good medication to use for a suppression test, as any cortisol above the expected level (meaning a failure to suppress or failure to suppress enough) can be said to be caused by a process working outside of the normal feedback loop (ie, a tumor).
This is a well-used type of test, and sadly, it is often used to rule out Cushing's when that really isn't what it is good for. These tests have a statistically high number of false negatives (I've seen published numbers as high as 30%), meaning there is a large chunk of patients who DO suppress on this test who still do go on to be proven to have Cushing's. And if you throw in the ectopic and cyclic patient groups rarely included in such studies, things really can get muddy. In my opinion as an educated patient, these tests are great for ruling IN Cushing's, but not for ruling it out. What I mean by that is that it misses a LARGE number of very ill patients, and some doctors then send them away still suffering, because of these test results (even when other testing comes back routinely diagnostic) so it is not a good test to use to rule out Cushing's as a problem. But it is good for proof of disease (ruling it in), because if you do not suppress fully on this test, it's pretty obvious there's a problem that needs further investigation and treatment. (Sadly, patients still get sent on their not-so-merry way...It's often the luck of the draw with doctors, even "specialists" as I explained in the "Testing introduction" post before.)
Something else Dex Suppression tests are good for: Helping to point towards source. Adrenal sources do not often suppress, and pituitary ones can. I honestly don't remember what ectopic sources do! I would assume they do not suppress either, or at least not much. But this test alone isn't a sufficient indicator anyway, and more tests and imaging are required to confirm source. So, really, it's kind of a shot in the dark whether this test is even useful.
*Update: Another Cushie asked if I would address the Dex-CRH test, and since I don't know too much, I'll just add it here. I attended the 2014 Magic Convention and heard Dr. Ludlam (Endocrinologist that used to run "Camp Cushie" at Swedish in Seattle but that now works as the endocrinology director at Novartis Pharmaceuticals) speak, and he did discuss the Dex-CRH. Keep in mind this is year-old memory I'm speaking from, so it's accuracy is suspect. My impression is that he found it far more accurate than the Dex alone and that he was of the opinion that by using the Dex to suppress normal pituitary function, he could then use CRH (Corticotropic Releasing Hormone) to force an ACTH-producing tumor to produce, and that this resulted in less (or no?) false negatives and far more accurate testing, especially in the episodic and cyclic patient population (he preferred the term "variable"). I have no data to back this up, and it appears I didn't include this in my post of notes last April, so take it for what it is worth. I've not heard of it being used since (which doesn't mean no one does it, but just that it isn't likely routinely or commonly used) and have not had the test myself.
Here's some info from Dr. Friedman's website:
"Dexamethasone-CRH Test
Another recommended test to distinguish between mild Cushing's syndrome and pseudo-
Cushing's states in those patients with a mildly elevated UFC is the dexamethasone-CRH test. This
test combines two tests, the low-dose dexamethasone suppression test (LDDST) and the CRH test
which individually are good but not great at distinguishing between pseudo-Cushing's states and
Cushing's syndrome. As discussed below, the dexamethasone test takes advantage of the fact that in
patients with Cushing's syndrome, dexamethasone ineffectively suppresses the production of pituitary
ACTH. CRH stimulates the pituitary to secrete ACTH which leads to an increase in cortisol levels.
Patients with Cushing's syndrome have a larger increase in plasma ACTH and cortisol levels than in
normal individuals or those patients with pseudo-Cushing's states. Although these tests individually
are helpful to diagnose Cushing's syndrome, many patients with pseudo-Cushing's states also respond
to them in a similar manner as those with Cushing's syndrome, making them not the ideal test to use
individually. Yanovski et al., (9) elected to combine the two tests and gave 39 patients with Cushing’s
syndrome and 19 patients with pseudo-Cushing’s states dexamethasone (0.5 mg) 4 times a day for 2
days starting at 12 noon (last dose at 6 A.M.). At 8 A.M. on the day of the last dose, the patients
received intravenous ovine CRH (1 μg/kg) and cortisol and ACTH were measured at various times.
All patients with Cushing’s syndrome had mild hypercortisolemia (UFC between 250 and 1000
nmol/d; 90-362 μg/d) so that UFCs between patients with Cushing’s syndrome and pseudo-Cushing’s
states completely overlapped. A plasma cortisol greater than 1.4 μg/dl (38 nmol/L) measured 15
minutes after the CRH injection correctly identified all patients with Cushing’s syndrome, while a
value less than 1.4 μg/d identified all patients with pseudo-Cushing’s states (100% sensitivity and
specificity). In contrast, the low dose dexamethasone test, had a 74% specificity and 69% sensitivity
when 17-OHS was measured on the second day of dexamethasone administration and 100% sensitivity and 56% sensitivity when UFCs were measured. The CRH stimulation test without dexamethasone pretreatment had 100% specificity and 64% sensitivity. This study has the advantage of comparing the dexamethasone-CRH test to other popular tests (LDDST and CRH test) in the same group of patients with mild Cushing’s syndrome and pseudo-Cushing’s states and clearly showed the superiority of the dexamethasone-CRH test in this group of patients. The main drawbacks to this test is that it requires a lot of steps and the drug (CRH), while no longer investigational, is expensive. A subsequent paper (70), found, as expected, that the dexamethasone-CRH test completely distinguished patients with Cushing’s syndrome from normal volunteers."
Full PDF of article found here.
These tests are kind of the opposite of a "stim" test in that it isn't meant to stimulate production, but to suppress it. The point of these tests is to give your body sufficient steroids (Dexamethasone) so that your pituitary's own feedback will stop it's production of ACTH. In a healthy HPA axis, your body recognizes there is already enough in your system, and thus doesn't produce more. They give the medication a set number of hours for your pituitary to respond, and then check your cortisol levels to see how much your cortisol has suppressed (or dropped).
Many forms of steroid replacement medication will show up as "cortisol" on lab tests, but in the testing used here, Dex does not. This makes it a good medication to use for a suppression test, as any cortisol above the expected level (meaning a failure to suppress or failure to suppress enough) can be said to be caused by a process working outside of the normal feedback loop (ie, a tumor).
This is a well-used type of test, and sadly, it is often used to rule out Cushing's when that really isn't what it is good for. These tests have a statistically high number of false negatives (I've seen published numbers as high as 30%), meaning there is a large chunk of patients who DO suppress on this test who still do go on to be proven to have Cushing's. And if you throw in the ectopic and cyclic patient groups rarely included in such studies, things really can get muddy. In my opinion as an educated patient, these tests are great for ruling IN Cushing's, but not for ruling it out. What I mean by that is that it misses a LARGE number of very ill patients, and some doctors then send them away still suffering, because of these test results (even when other testing comes back routinely diagnostic) so it is not a good test to use to rule out Cushing's as a problem. But it is good for proof of disease (ruling it in), because if you do not suppress fully on this test, it's pretty obvious there's a problem that needs further investigation and treatment. (Sadly, patients still get sent on their not-so-merry way...It's often the luck of the draw with doctors, even "specialists" as I explained in the "Testing introduction" post before.)
Something else Dex Suppression tests are good for: Helping to point towards source. Adrenal sources do not often suppress, and pituitary ones can. I honestly don't remember what ectopic sources do! I would assume they do not suppress either, or at least not much. But this test alone isn't a sufficient indicator anyway, and more tests and imaging are required to confirm source. So, really, it's kind of a shot in the dark whether this test is even useful.
*Update: Another Cushie asked if I would address the Dex-CRH test, and since I don't know too much, I'll just add it here. I attended the 2014 Magic Convention and heard Dr. Ludlam (Endocrinologist that used to run "Camp Cushie" at Swedish in Seattle but that now works as the endocrinology director at Novartis Pharmaceuticals) speak, and he did discuss the Dex-CRH. Keep in mind this is year-old memory I'm speaking from, so it's accuracy is suspect. My impression is that he found it far more accurate than the Dex alone and that he was of the opinion that by using the Dex to suppress normal pituitary function, he could then use CRH (Corticotropic Releasing Hormone) to force an ACTH-producing tumor to produce, and that this resulted in less (or no?) false negatives and far more accurate testing, especially in the episodic and cyclic patient population (he preferred the term "variable"). I have no data to back this up, and it appears I didn't include this in my post of notes last April, so take it for what it is worth. I've not heard of it being used since (which doesn't mean no one does it, but just that it isn't likely routinely or commonly used) and have not had the test myself.
Here's some info from Dr. Friedman's website:
"Dexamethasone-CRH Test
Another recommended test to distinguish between mild Cushing's syndrome and pseudo-
Cushing's states in those patients with a mildly elevated UFC is the dexamethasone-CRH test. This
test combines two tests, the low-dose dexamethasone suppression test (LDDST) and the CRH test
which individually are good but not great at distinguishing between pseudo-Cushing's states and
Cushing's syndrome. As discussed below, the dexamethasone test takes advantage of the fact that in
patients with Cushing's syndrome, dexamethasone ineffectively suppresses the production of pituitary
ACTH. CRH stimulates the pituitary to secrete ACTH which leads to an increase in cortisol levels.
Patients with Cushing's syndrome have a larger increase in plasma ACTH and cortisol levels than in
normal individuals or those patients with pseudo-Cushing's states. Although these tests individually
are helpful to diagnose Cushing's syndrome, many patients with pseudo-Cushing's states also respond
to them in a similar manner as those with Cushing's syndrome, making them not the ideal test to use
individually. Yanovski et al., (9) elected to combine the two tests and gave 39 patients with Cushing’s
syndrome and 19 patients with pseudo-Cushing’s states dexamethasone (0.5 mg) 4 times a day for 2
days starting at 12 noon (last dose at 6 A.M.). At 8 A.M. on the day of the last dose, the patients
received intravenous ovine CRH (1 μg/kg) and cortisol and ACTH were measured at various times.
All patients with Cushing’s syndrome had mild hypercortisolemia (UFC between 250 and 1000
nmol/d; 90-362 μg/d) so that UFCs between patients with Cushing’s syndrome and pseudo-Cushing’s
states completely overlapped. A plasma cortisol greater than 1.4 μg/dl (38 nmol/L) measured 15
minutes after the CRH injection correctly identified all patients with Cushing’s syndrome, while a
value less than 1.4 μg/d identified all patients with pseudo-Cushing’s states (100% sensitivity and
specificity). In contrast, the low dose dexamethasone test, had a 74% specificity and 69% sensitivity
when 17-OHS was measured on the second day of dexamethasone administration and 100% sensitivity and 56% sensitivity when UFCs were measured. The CRH stimulation test without dexamethasone pretreatment had 100% specificity and 64% sensitivity. This study has the advantage of comparing the dexamethasone-CRH test to other popular tests (LDDST and CRH test) in the same group of patients with mild Cushing’s syndrome and pseudo-Cushing’s states and clearly showed the superiority of the dexamethasone-CRH test in this group of patients. The main drawbacks to this test is that it requires a lot of steps and the drug (CRH), while no longer investigational, is expensive. A subsequent paper (70), found, as expected, that the dexamethasone-CRH test completely distinguished patients with Cushing’s syndrome from normal volunteers."
Full PDF of article found here.
Friday, April 24, 2015
Testing for Cushing's, CBG
Serum Cortisol Binding Globulin (CBG) is another simple blood draw. This one you don't do often, but just so your endocrinologist can get a feel for whether your CBG is high, low or normal.
This test measures the amount of cortisol in your blood that is in bound form. My understanding is that free cortisol is the active form, so it is the most important for determining hypercortisolism. Since a fair amount of the testing used gives results in "total cortisol" it is useful to rule out other causes for test elevation.
If your CBG is high, it can make your total cortisol results also come back high, even though it may not actually be problematic. One specific instance in which high CBG is known to be elevated and confuse testing is with oral birth control pills. They raise your CBG level and can skew (and invalidate) any test results while on them. For this reason it is suggested you be off oral birth control (estrogens specifically, I believe) for a minimum of 6 weeks prior to cortisol testing. And always inform your endocrinologist of all medications and supplements you are taking, including other forms of hormonal birth control, etc.
This test measures the amount of cortisol in your blood that is in bound form. My understanding is that free cortisol is the active form, so it is the most important for determining hypercortisolism. Since a fair amount of the testing used gives results in "total cortisol" it is useful to rule out other causes for test elevation.
If your CBG is high, it can make your total cortisol results also come back high, even though it may not actually be problematic. One specific instance in which high CBG is known to be elevated and confuse testing is with oral birth control pills. They raise your CBG level and can skew (and invalidate) any test results while on them. For this reason it is suggested you be off oral birth control (estrogens specifically, I believe) for a minimum of 6 weeks prior to cortisol testing. And always inform your endocrinologist of all medications and supplements you are taking, including other forms of hormonal birth control, etc.
Thursday, April 23, 2015
Testing for Cushing's, ACTH
Serum Adrenal Corticotropin Releasing Hormone (ACTH) is a hormone produced by your pituitary. This hormone signals the adrenals to produce more cortisol. It is a simple blood draw, done at specific times (8am or midnight) and is only complicated by its need to be drawn into a chilled tube and kept frozen. It has a super-short half life (somewhere around 14-17 minutes, depending on the source), meaning the levels present in a blood sample drop quickly at room temperature. I *always* remind the lab aid about this tests' requirements if they haven't already obviously prepared a chilled tube, etc. Depending on the lab, this test can take a bit longer than the cortisol, but it too has a fairly quick turn around. A serum ACTH level can be a very helpful test for diagnosis as it helps point to the source of the excess cortisol state endogenous hypercortisolism (ie, the problem stems from within the body).
In the case of Cushing's Disease, there is a tumor on the pituitary that produces it's own ACTH, effectively bypassing the feedback loop that would otherwise keep your levels just where you need them in a healthy body. This in turn causes your adrenals to produce cortisol your body doesn't actually need, and it sets off a huge chain of events that can cause a lot of damage to your body. In this situation it also suppresses your own pituitary's production of ACTH (there is already enough in the blood supply, so your pituitary does not call for more) with it basically going to sleep as it gets out of the habit. In cyclic cases, it is thought that the tumor turns off production (this is poorly understood and there is no explanation as to why or how, to my knowledge), and this accounts for a cyclic person swinging into a "low cycle" or normal cycle. For this reason, the pituitary of a cyclic patient doesn't always become fully suppressed and post-operative testing may not be as clear. If the pituitary can wake up and kick in, your body may not crash to a "zero cortisol state" postoperatively as is expected and watched for as a sign for remission in florid cases (though it certainly still does happen). It also may mean a lower requirement for post-op steroid replacement. But this is all so individual, dependent upon your pre-operative levels, and how your body copes with the changes.
ACTH within the normal range or somewhat elevated in the presence of hypercortisolism is suggestive of a pituitary tumor source as described above.
Low or absent ACTH levels are indicative of an adrenal source, meaning there is a tumor on an adrenal glad itself that instead of producing ACTH, produces cortisol more directly. Your pituitary senses the excess cortisol and thus does not send out ACTH to produce more. This too can lead to pituitary suppression.
An excessively high ACTH level is suggestive of what is called an ectopic source. This can be a tumor almost anywhere else in the body, that produces high amounts of ACTH. There are some specific types of imaging that can help locate these tumors, which I'll discuss briefly in a later post.
The most common endogenous source is pituitary, a small percent is adrenal, and an even smaller percent are ectopic.
In the case of Cushing's Disease, there is a tumor on the pituitary that produces it's own ACTH, effectively bypassing the feedback loop that would otherwise keep your levels just where you need them in a healthy body. This in turn causes your adrenals to produce cortisol your body doesn't actually need, and it sets off a huge chain of events that can cause a lot of damage to your body. In this situation it also suppresses your own pituitary's production of ACTH (there is already enough in the blood supply, so your pituitary does not call for more) with it basically going to sleep as it gets out of the habit. In cyclic cases, it is thought that the tumor turns off production (this is poorly understood and there is no explanation as to why or how, to my knowledge), and this accounts for a cyclic person swinging into a "low cycle" or normal cycle. For this reason, the pituitary of a cyclic patient doesn't always become fully suppressed and post-operative testing may not be as clear. If the pituitary can wake up and kick in, your body may not crash to a "zero cortisol state" postoperatively as is expected and watched for as a sign for remission in florid cases (though it certainly still does happen). It also may mean a lower requirement for post-op steroid replacement. But this is all so individual, dependent upon your pre-operative levels, and how your body copes with the changes.
ACTH within the normal range or somewhat elevated in the presence of hypercortisolism is suggestive of a pituitary tumor source as described above.
Low or absent ACTH levels are indicative of an adrenal source, meaning there is a tumor on an adrenal glad itself that instead of producing ACTH, produces cortisol more directly. Your pituitary senses the excess cortisol and thus does not send out ACTH to produce more. This too can lead to pituitary suppression.
An excessively high ACTH level is suggestive of what is called an ectopic source. This can be a tumor almost anywhere else in the body, that produces high amounts of ACTH. There are some specific types of imaging that can help locate these tumors, which I'll discuss briefly in a later post.
The most common endogenous source is pituitary, a small percent is adrenal, and an even smaller percent are ectopic.
Wednesday, April 22, 2015
Testing for Cushing's, MN Serum Cort
Midnight Serum Cortisol is a simple blood test that can be a good diagnostic tool for Cushing's Disease or Syndrome. You see, cortisol should be at it's lowest point around midnight in a healthy person, so it is a good time to test for excess because the range for "normal" is so small.
It's a simple blood draw like any other, though at least the fist one should include a serum ACTH (will be addressed in a future post) to get a better picture of what is happening with your pituitary and your adrenals. These results come back quickly, too (BONUS! No 2 week wait!).
The difficulty in this test is getting the lab to draw them. I had great luck locally contacting the hospital's lab manager, explaining the test my doctor ordered, and requesting they draw it. I explained that I would happily come in 30-60 minutes early and stay 30-60 minutes late should they be busy, giving a decent draw window for their one tech on duty at that time of night (It's a small hospital). I was very lucky and they agreed to do it.
I did have to enter through the ER entrance, but the security guards and ER nurses recognized me quickly (I did a series of 4 nights in a row) and admitting staff had been told I would be coming in for testing and thus admitted me as outpatient. The diagnostic cutoff typically is 7.5 for a midnight draw. Anything above that is considered diagnostic. For a sleeping midnight draw (if you were spending the night at the hospital in their bed), the diagnostic cutoff is actually only 3.
Personally, I love this test. I think the timing is still more convenient (and the results faster and more universally accurate) than the inconvenience and shortcomings of the 24 hour urine tests.
(Note: it is also worthwhile to have had a CBG recently, as that can affect a total serum cortisol draw --more details in a future post).
It's a simple blood draw like any other, though at least the fist one should include a serum ACTH (will be addressed in a future post) to get a better picture of what is happening with your pituitary and your adrenals. These results come back quickly, too (BONUS! No 2 week wait!).
The difficulty in this test is getting the lab to draw them. I had great luck locally contacting the hospital's lab manager, explaining the test my doctor ordered, and requesting they draw it. I explained that I would happily come in 30-60 minutes early and stay 30-60 minutes late should they be busy, giving a decent draw window for their one tech on duty at that time of night (It's a small hospital). I was very lucky and they agreed to do it.
I did have to enter through the ER entrance, but the security guards and ER nurses recognized me quickly (I did a series of 4 nights in a row) and admitting staff had been told I would be coming in for testing and thus admitted me as outpatient. The diagnostic cutoff typically is 7.5 for a midnight draw. Anything above that is considered diagnostic. For a sleeping midnight draw (if you were spending the night at the hospital in their bed), the diagnostic cutoff is actually only 3.
Personally, I love this test. I think the timing is still more convenient (and the results faster and more universally accurate) than the inconvenience and shortcomings of the 24 hour urine tests.
(Note: it is also worthwhile to have had a CBG recently, as that can affect a total serum cortisol draw --more details in a future post).
Tuesday, April 21, 2015
Testing for Cushing's, 10 hr UFC
10 hour Urinary Free Cortisol is basically the same as a 24 hour UFC (in fact, most labs run it as a 24 hour sample), but you collect your urine for 10 hours only, between 10pm and 8am.
This test is used specifically to look for a flipped diurnal rhythm...if your body produces too much cortisol at night, most often in patients who have mixed test results. This is the time of day your cortisol production should be at it's lowest, so it is a great time of day to test for excess cortisol (as we'll also discuss later with midnight testing).
The result used for this specific test is the cortisol/creatinine ratio. My endocrinologist uses a cut off of 16 and above (or is it just above?) for diagnosis. Sometimes the labs don't calculate it all (Some do routinely, some don't) and you have to specifically request the ratio.
A word to the wise about dealing with labs if they aren't used to this test: They can get confused if there is no "10 hour UFC" lab listed in their computers. I always tell mine to order it AS a 24 hour UFC when that is the case. My favorite local lab has no qualms asking me how to order testing correctly, which I MUCH prefer to wasting my time, pee, and money! (Isn't it nice to be treated like you know what you're doing?!)
The one key here is that THEY MUST ENTER THE TOTAL VOLUME AND COLLECTION HOURS IN THE COMPUTER! If not, you can call back later to fix it assuming they run the test and don't just toss the sample, but that's annoying to have to do too. And sometimes you run into people who act like you're the one who's confused or made the error. Just ask my friend who takes pictures of her jugs' labels...she's had to offer to send them a few times as proof!
This test is used specifically to look for a flipped diurnal rhythm...if your body produces too much cortisol at night, most often in patients who have mixed test results. This is the time of day your cortisol production should be at it's lowest, so it is a great time of day to test for excess cortisol (as we'll also discuss later with midnight testing).
The result used for this specific test is the cortisol/creatinine ratio. My endocrinologist uses a cut off of 16 and above (or is it just above?) for diagnosis. Sometimes the labs don't calculate it all (Some do routinely, some don't) and you have to specifically request the ratio.
A word to the wise about dealing with labs if they aren't used to this test: They can get confused if there is no "10 hour UFC" lab listed in their computers. I always tell mine to order it AS a 24 hour UFC when that is the case. My favorite local lab has no qualms asking me how to order testing correctly, which I MUCH prefer to wasting my time, pee, and money! (Isn't it nice to be treated like you know what you're doing?!)
The one key here is that THEY MUST ENTER THE TOTAL VOLUME AND COLLECTION HOURS IN THE COMPUTER! If not, you can call back later to fix it assuming they run the test and don't just toss the sample, but that's annoying to have to do too. And sometimes you run into people who act like you're the one who's confused or made the error. Just ask my friend who takes pictures of her jugs' labels...she's had to offer to send them a few times as proof!
Monday, April 20, 2015
Testing for Cushing's, 17 ohc/17 ohs
24 hour 17-hydroxycorticosteroids (17 ohc/17ohs) is a test that used to be the gold standard back before my time, was all-but thrown out when 24 hr UFC's came along, and is now making a bit of a come-back.
A 17ohc is also a 24 hour urine collection and is collected in exactly the same manner a 24 hour UFC. And...as long as the lab processes it correctly (and neither require preservative at your particular lab), you can also run BOTH a UFC and 17ohc off of one 24 hour urine collection sample (IE, the same 24hr period, the same jug). This makes it a super convenient test to add into the mix.
My understanding is that 17 ohc's are a product of the production/breakdown of cortisol within the body. So, instead of measuring the amount of cortisol your body is passing unused through your kidneys, it is measuring what is more akin to the amount of cortisol your body produced (what is passed into your urine and what was metabolized elsewhere in your body).
Despite having been practically replaced by the 24 hr UFC to the point that labs stopped offering the test and more-recently-trained doctors didn't learn much about it, they are now finding that it is a useful test in helping to confirm cyclic or episodic disease when other test results are mixed (in a situation where some testing comes back high and others come back low/normal).
The results used in this test are the mg/day (as opposed to mg/creat).
A 17ohc is also a 24 hour urine collection and is collected in exactly the same manner a 24 hour UFC. And...as long as the lab processes it correctly (and neither require preservative at your particular lab), you can also run BOTH a UFC and 17ohc off of one 24 hour urine collection sample (IE, the same 24hr period, the same jug). This makes it a super convenient test to add into the mix.
My understanding is that 17 ohc's are a product of the production/breakdown of cortisol within the body. So, instead of measuring the amount of cortisol your body is passing unused through your kidneys, it is measuring what is more akin to the amount of cortisol your body produced (what is passed into your urine and what was metabolized elsewhere in your body).
Despite having been practically replaced by the 24 hr UFC to the point that labs stopped offering the test and more-recently-trained doctors didn't learn much about it, they are now finding that it is a useful test in helping to confirm cyclic or episodic disease when other test results are mixed (in a situation where some testing comes back high and others come back low/normal).
The results used in this test are the mg/day (as opposed to mg/creat).
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