Chapter 23: Differences Between Laboratories

Hilgers TW

Research Methods Measurement and Statistics

Chapter 23: Differences Between Laboratories

Hilgers TW

The Medical and Surgical Practice of NaProTECHNOLOGY, 281-284, 2004

RRM Academy Synopsis

Hormone results for one blood sample can differ between laboratories

Hormone results for the same blood sample can differ between labs. A textbook chapter explains why. It shows that a normal range from one lab can misjudge results from another lab. Examples cover two hormones, progesterone and estradiol.

Key Findings

The chapter names three layers of variation in reproductive hormone tests: biologic variation, assay variation, and a day-to-day or week-to-week variation linked to time.
In a worked example of progesterone in pregnancy, the same results read as normal against Laboratory B's range and clearly suboptimal against Laboratory A's range.
Table 23-1 lists same-patient, same-date, same-specimen progesterone and estradiol results from an outside laboratory and the National Hormone Laboratory. The variation was very large in some cases and minimal in others.
Comparing 1974 studies with 2004 studies, the coefficient of variation for progesterone assays is lower now. The chapter credits improved analytical technique over the last 30 years.
The chapter states that laboratories commonly do not set normal levels for menstrual and fertility cycle hormones. Its normograms apply only to results from the National Hormone Laboratory.

RRM Context

Cycle-charting-informed care asks when a blood sample was drawn as well as what it shows. The chapter notes that tracking biomarkers with the CREIGHTON MODEL FertilityCare System helps control time-linked variation. A normal result depends on the laboratory's own range and the day of the cycle. Evaluation before treatment starts with data that can be interpreted.

Our editorial summary of this paper, not the article's abstract.

Abstract

This chapter explains that laboratory hormone results carry both biologic and assay variation, and that hormones of the menstrual cycle and pregnancy add a time-linked, day-to-day or week-to-week variation. Using progesterone in pregnancy as an example, Hilgers shows how the same results can read as normal against one laboratory's normal range and as suboptimal against another's. The chapter states that the normograms published in the textbook apply only to hormone levels measured in the National Hormone Laboratory of the Pope Paul VI Institute, and it describes two ways to resolve the difference: using that laboratory as a reference laboratory or correlating a local laboratory against it. A comparison of the precision of progesterone assays in 1974 and 2004 is presented to show that assay variability has decreased over 30 years.

Topics

Research Methods › Measurement and Statistics › Research Tooling and Reproducibility · Diagnostics › Hormone Testing › Serum Panels · Reproductive Endocrinology › Ovarian Hormones › Estrogen

Thomas W Hilgers

Tom Hilgers, T Hilgers

Hilgers et al. 2004, Hilgers 2004

Chapter 23: Differences Between Laboratories

Hormone results for one blood sample can differ between laboratories

Key Findings

RRM Context

Abstract

Topics

By this author

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