Dr. Mariano–Free serum cortisol LC/MS/MS

[mylilcappi]

Dr. M
When a blood cortisol is taken and it has LC/MS/MS beside it, what does it mean?
I looked it up and it said it is a specific way of testing the cortisol?

According to my testing that is the way on of my morning corisol was tested?

THanks,
Mamie

[leanguy]

LC/MS = Liquid Chromatography/Mass Spectrometry

[mylilcappi]

But what does it mean? What is the difference when they run that test vs. one without LC/MS/MS?

[DrMariano2]

@mylilcappi 1030 wrote:

But what does it mean? What is the difference when they run that test vs. one without LC/MS/MS?

There are various ways to measure something.

Mass Spectrometry is one of the standards.

To do further separation, for free levels (for example), some do equilibrium dialysis.

When a method is not specified, one doesn’t know what test was done. Sometimes, one can guess by the reference range used.

For example, I recently got results on a patient where the Free T3 was tested with Mass Spectrometry and was again tested using Equilibrium dialysis. The equilibrium dialysis reference scale was much larger than the Mass Spectrometry scale. I wasn’t use to reading it having no experience with it. I could not rely on the value it gave since it was higher than the Mass Spectrometry value that I was use to. Using it with the MS scale would give a wrong interpretation. To use the equilibrium dialysis method for Free T3, I would have to use it perhaps at least one hundred times to get a feel of what the correct levels are. Otherwise, it really isn’t useful to me.

[mylilcappi]

Ok.. Sorry. I get so confused about all this.

Is was a total serum cortisol. using LC/MS/MS

It came back high 25.1. with a range of 4-20.6.
so I was wondering using this method of testing, is that a true reading? or would you know?
Thanks.
I know it’s not THAT high, but was just wondering.

[DrMariano2]

@mylilcappi 1039 wrote:

Ok.. Sorry. I get so confused about all this.

Is was a total serum cortisol. using LC/MS/MS

It came back high 25.1. with a range of 4-20.6.
so I was wondering using this method of testing, is that a true reading? or would you know?
Thanks.
I know it’s not THAT high, but was just wondering.

The term “True Reading” has no meaning.

The test gave a result. The test gives a consistent result.

A result of 25 for Cortisol is above the reference range of 4-20.6.

It is then a matter of what interpretation one has for the result.

When it comes to cortisol results, It is hard to tell whether it is high or not unless I know the circumstances of the patient.

When patients, for example, are in extremely stressful situations, then a result of 25 may be considered just right or low. In patients who are in low levels of stress, the result of 25 may be considered elevated, though not excessively high. The reference range shifts depending on the stress level. A reference range of 4-20.6 assumes a person at rest, in an unstressed state.

Knowing the other adrenal signal values (DHEA-s, Progesterone, Pregnenolone, Testosterone, Estradiol, Aldosterone, etc.) may be helpful to determine how the adrenals are functioning.

[mylilcappi]

Well, in April I had a DHEA-s come back at 237 (0-150)

Also in May I had a Dhea-s come back at 211 ((32-240)
In April I had a IGF-1 come back at 643 (81-250)
In may it came back 365 (94-252)

I had a GTT and suppressed GH..
Had mammogram negative
And just went to my gyno to have her check my breasts. She did not find anything.
Thanks for your time.

[DrMariano2]

@mylilcappi 1048 wrote:

Well, in April I had a DHEA-s come back at 237 (0-150)

Also in May I had a Dhea-s come back at 211 ((32-240)
In April I had a IGF-1 come back at 643 (81-250)
In may it came back 365 (94-252)

I had a GTT and suppressed GH..
Had mammogram negative
And just went to my gyno to have her check my breasts. She did not find anything.
Thanks for your time.

Generally, a DHEA-s between 200-300 in a woman is good.

IGF-1 significantly above 250-400 is pretty good. When it is significantly above the reference range, I would wonder if one has a pituitary tumor secreting growth hormone.

[mylilcappi]

Dr. M,
That first IGF-1 is way above the range I would think.
I know the second was isn’t but still above.

Taken by two different labs in a short time frame.
I don’t know which lab to believe. This concerns me..

Also, in one day,
I tested for several things.

different labs..
One lab my sodium and potassium were OVER range.
another lab normal..
In one day’s drawing.

I don’t know about these labs.

[DrMariano2]

@mylilcappi 1062 wrote:

Dr. M,
That first IGF-1 is way above the range I would think.
I know the second was isn’t but still above.

Taken by two different labs in a short time frame.
I don’t know which lab to believe. This concerns me..

Also, in one day,
I tested for several things.

different labs..
One lab my sodium and potassium were OVER range.
another lab normal..
In one day’s drawing.

I don’t know about these labs.

Here is Quest Diagnostics IGF-1 monograph:
http://questdiagnostics.com/hcp/intguide/EndoMetab/EndoManual_AtoZ_PDFs/IGF_I.pdf

Using an Immunochemiluminometric Assay (ICMA), the reference range for IGF-1 for an 18-30 year-old adult is:
Male: 126-382 ng/mL
Female: 138-410 ng/mL

Here is Arup Labs information:
http://www.aruplab.com/guides/ug/tests/0070125.jsp

Using the same test – this time named: Chemiluminoescent Immunoassay, the reference range for an 18-30 adult is:
Male: 112-497 ng/mL
Female: 89-488 ng/mL
(I combined the age ranges they had)

Here is LabCorp’s information:
https://www.labcorp.com/wps/portal/!ut/p/c1/04_SB8K8xLLM9MSSzPy8xBz9CP0os_hACzO_QCM_IwMLXyM3AyNjMycDU2dXQwN3M6B8JG55AwMCusNB9uHXD5I3wAEcDfT9PPJzU_Uj9aPM40NdTYINPS2NDfxd3Q0MjMw9fTwtLfwNDYwN9UP0C3IjDLJMIhUB94XRqA!!/dl2/d1/L0lDU0lKSmdvS1VRIS9JSFNBQ0lpTXlDb3FiRURBSUEhIS9ZQTQ1NDUwLTVGMHN0eWp3LzdfVUU0UzFJOTMwT0VHMDAyN0lMSTk4TzEwMzEvQVFfX185Ni9zcGZfQWN0aW9uTmFtZS9zcGZfQWN0aW9uTGlzdGVuZXI!/?testId=408396&spf_strutsAction=%212fshowDetail.do

Using the same test (Immunochemiluminometric assay (ICMA)), LabCorp’s range for 18-30 y.o. adults for both men and women is:
116-483 ng/mL (I combined the age ranges they have)

—-

Note that each lab has a different range. This is to be expected.

Each lab determines the reference range only from the patients they see. Thus, if each lab has a different population of patients, the reference ranges will be different. For example, with the above numbers, I would assume Quest Diagnostics sees sicker patients since their range is lower.

However, making a decision on the reference range to use is also arbitrary. Labs, unless directly asked of the lab director, generally don’t have information as to why they chose a particular reference range. One lab director I know, for example, told me he chose to use the 20th percentile and 80th percentile as reference range points. The primary reason for this – instead of the research expected 2 standard deviations from the mean? So that some people will fall out of the range. To use 2 standard deviations from the mean as a reference point would leave virtually no one outside the reference range. Thus the arbitrary decision had to be made so that some people can be called “sick” rather than “within-normal-range.”

Since the technique is the same, hopefully, one can assume that the numbers are going to be about the same if the lab was done at precisely the same time.

I suppose one could test this by obtaining several red-top tube specimens at the same time, refrigerating them, then sending one specimen to each lab.

Lab values may vary depending on the time of day. DHEA values, for example, vary an enormous amount each minute.

If one settles down on a single lab to do all of one’s testing, then one hopes to at least get consistent levels, for which a clinical decision may be made, once the physician gets use to a particular lab’s reference ranges and how they correlate with clinical presentation.

—

When making clinical decisions, it is important to determine a standardized method to use to determine the lab level. Some labs use one technique, others use another technique.
The clinician, after having experience in correlating the history and physical to the lab test, would then be able to rely on the lab test to make decisions.

It is the experience here that counts. This is why one pays a professional.

In medicine, one of the most important things is that the history and physical should correlate with the lab test. If it does not, then the lab test would be questionable.

For example, if one has consistently very high IGF-1 levels, over a period of time, which generally correlate with high growth hormone levels, one should reasonably expect the history and physical to reflect acromegaly or gigantism. If it does not, then the test is questionable in validity.

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