Validation

PT and PTT Reference Interval

Here are the results of our latest Quick Question: How many normal subject specimens do you collect to establish a PT and PTT reference interval? a. 240: 7 votes, 3% b. 120: 79 votes, 35% c. 30: 51 votes, 23% d. 20: 79 votes, 35% e. Other: 9 votes, 4% Comments excerpted from Fritsma GA. […]

Quick Question Archive

More on Validations Using Commercial Plasmas

John Olson, MD, provides his position on the use of commercial plasmas for lot-to-lot validations (rollover) and for establishing reference intervals. Though associated with CAP, Dr. Olson’s opinion does not necessarily reflect the official CAP policy. “I would not have difficulty with a laboratory using commercial sets for determining reference interval. By far the best […]

Subjects in Reference Interval Study

Mona Murphy, Pathology Laboratory, Lewiston, ME reports using 20 males and 20 females in a normal range study.

Quick Question Archive

Validations Using Commercial Plasmas

Chris Powell at King’s Daughters’ Health asks: commercial plasma distributors offer pre-screened patient specimens for PT and PTT lot rollover. How can this product be used and still meet the CAP and CLIA requirement to collect specimens from your own patient population? Hi, Chris, thank you for your question. I’ve modified your reference to a […]

PNP: How Many Donors?

From Dr. Tang: Dear George, In the mixing test, commonly 20 healthy donors is required for preparing normal pooled plasma, why not 15, 10, or 5 donors? Have any studies validated that? Thank you for your reply. Hello, Dr. Tang. I know of no published studies that establish 20 donors as a minimum for producing […]

Specimen Management

Elevated Protein C Activity

From colleague and friend Kelly Townsend, Tricore Laboratories, Albuquerque: We periodically see elevated protein C activity results in our rheumatology patients. We’ve been wondering what might be leading to this finding. They do not all have positive LA, and in fact tend to have PTT‘s in the lower half of the reference interval (sometimes quite […]

Lupus Anticoagulant

APCR Controls

From Sheila Minor: We are currently using the Chromogenix Coatest APC Resistance VS kit for APCR testing. Chromogenix provides 1 set of level 1 and level 2 controls in each kit. The instructions state that the controls may be refrozen one time at –20 C or colder in their original vials. That would be fine if we used […]

Reference Intervals: December QQ

We’ve just posted a new Quick Question, and have already received this response from Heather DeVries, Indiana University Health. I just logged in and saw the new Quick Question. I am excited to be the first to respond! Of course my answer is not simple. As a system, we use close to 300 normals to […]

Quick Question Archive

More on RIs in Multiple Sites

We’ve received follow-up insights on our 12-2-15 post, Reference Intervals in Multiple Sites: From Dr. Emmanuel Favaloro, Institute of Clinical Pathology and Medical Research: I suspect that everyone will have a slightly different perspective on this question, as informed from personal experience. We run a network of 27 labs, all using Stago instrumentation, but either […]

Effect of HCT on POC INR

George received this question from the ASCLS Consumer Web Forum via Bonnie Jo Taylor, MHS, MT(ASCP)SH. I have hemochromatosis, too much iron in my blood. I’ve also had blood clots in my lungs. I peroidically undergo phlebotomy treatments to lower iron count. Will this alter the results of my INR finger prick test results? Here […]

Anticoagulant Therapy

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George Fritsma is a medical laboratory scientist, educator, and author. George is a member of the International Society on Thrombosis and Hemostasis, the International Society for Laboratory Hematology, and the American Society for Clinical Laboratory Science.

Cheat Sheets from George

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