Psa lab vary

[Peterd110]

Does anyone know by how much I could expect 2 different lab’s psa values to differ?

[LearnAll]

There are two main type of methods,,,Quest Lab (USA) uses Siemens Systems in which PSA comes 20 % lower than the other commonly used method called.. Beckman-Coulter.

You need to ask lab what system they are using to measure your PSA so that you can use the same system each time to get correct readings for comparison.

[Cancer2x in reply to LearnAll]

Becman coulter measured my PSA at .043, while Quest came back at 0.3. VA, test unknown was 0.43.

I think that depending on the assay type, freshness of the assay chemicals, and skill of the test operator there will be result variations everywhere.

[Hidden]

Some major cancer centers don't go any lower than <.1. Some go to the second, third decimal. Story. I was at a major, highly rated cancer center to see my oncologist and my psa came back as <.1. The very next day while I was at a VA center, for some reason my PCP ordered a psa test and it came back .005. Now they do use different machines to test psa values but I was slightly taken back. ( In a happy way). Go figure huh? As long as I see a <.1, I'm not going to stress about it.

[tango65]

This link have info comparing different techniques.:

sci-hub.tw/https://www.scie...

[pjoshea13]

Peter,

Thankfully, we are well past the days when two tests at the same lab, from the same blood draw, might give different numbers. Even so, I don't expect consistency between labs using the same method. I always use the same lab.

-Patrick

[j-o-h-n]

youtube.com/watch?v=KqaVacV...(Not working as expected?)

Good Luck, Good Health and Good Humor.

j-o-h-n Sunday 08/18/2019 1:44 AM DST

[dadzone43]

They MAY vary. The only way to find out is to contact the lab's pathologist-director and ask specifically for the variation on the test. All lava must retain this information. Or, on the same day give a sample at each lab and compare your results.

[herb1]

Couple of comments: 1. unfortunately, my quick read shows that the area of most interest , a psa of <<4, is still not well represented/studied. 2. The difference between a <0.05 and <0.1 may reflect the lowest level the lab feels can be reliably reported using their method. 3. Yes, there may be variability in values with hi psa, but IMO that area is academic since a high psa (>100) is a clear indication of problems.

[Peterd110]

Ok. Well here’s why I asked..... I am very aware that some labs can vary pretty significantly

Trelstar, zytiga since diagnosis a year ago. Psa 352

Psa <0.1 at quest through April

Began generic zytiga at beginning of April

-hMay psa is 0.1

-June psa is 0.2

-July psa is 0.4 at hosp lab so changed back to brand zytiga

-August psa is 0.97 at same hosp

-One week later dr checks psa at his facility and it is 0.65. ( I was expecting it to be over 1.2 with the increasing trend )

This is 1/3 difference not counting my expected increased value

Guess I will find out soon enough. I’ll just keep pressing on.