One group of frequent questions on this and many other forums is whether a test result is "normal", good or "optimum".
While we all try to answer helpfully, the truth is that it is almost unanswerable.
Part of the problem is that for many tests, there has never been adequate harmonisation. The same range, the same result, from two different labs could still actually be a bit different. (And that is even ignoring factors that interfere with tests - like biotin.)
But this paper goes further, much further, in explaining that each of us has our own setpoints. The paper is based on nine measurements made in a Complete Blood Count (Full Blood Count in the UK) - the precise tests do vary a little from lab to lab.
If you and I have very similar results today, and are healthy, then we'd expect to have very similar results in twenty years time.
But if we are different, we'd expect those differences to remain just as stable over a similar period. Unless there are health issues.
And this applies to many tests - not just CBC. They looked at lots of other tests.
They actually specifically mention "thyroid dysfunction"!
Perhaps one of the best things healthy people could do is to get a wide-ranging set of tests so that they can directly compare their own results in future with their own base-level?
Seems that this is yet another reason that we need to have full access to all tests we have had. Even if our GP has not got the time to compare results over decades, we might have. And we might be able to rule lots of things out.
I don't want to promote the private testing industry but it is very hard to avoid doing so!
Published: 11 December 2024
Haematological setpoints are a stable and patient-specific deep phenotype
Brody H. Foy, Rachel Petherbridge, Maxwell T. Roth, Cindy Zhang, Daniel C. De Souza, Christopher Mow, Hasmukh R. Patel, Chhaya H. Patel, Samantha N. Ho, Evie Lam, Camille E. Powe, Robert P. Hasserjian, Konrad J. Karczewski, Veronica Tozzo & John M. Higgins
Nature (2024)
Abstract
The complete blood count (CBC) is an important screening tool for healthy adults and a common test at periodic exams. However, results are usually interpreted relative to one-size-fits-all reference intervals1,2, undermining the precision medicine goal to tailor care for patients on the basis of their unique characteristics3,4. Here we study thousands of diverse patients at an academic medical centre and show that routine CBC indices fluctuate around stable values or setpoints5, and setpoints are patient-specific, with the typical healthy adult’s nine CBC setpoints distinguishable as a group from those of 98% of other healthy adults, and setpoint differences persist for at least 20 years. Haematological setpoints reflect a deep physiologic phenotype enabling investigation of acquired and genetic determinants of haematological regulation and its variation among healthy adults. Setpoints in apparently healthy adults were associated with significant variation in clinical risk: absolute risk of some common diseases and morbidities varied by more than 2% (heart attack and stroke, diabetes, kidney disease, osteoporosis), and absolute risk of all-cause 10 year mortality varied by more than 5%. Setpoints also define patient-specific reference intervals and personalize the interpretation of subsequent test results. In retrospective analysis, setpoints improved sensitivity and specificity for evaluation of some common conditions including diabetes, kidney disease, thyroid dysfunction, iron deficiency and myeloproliferative neoplasms. This study shows CBC setpoints are sufficiently stable and patient-specific to help realize the promise of precision medicine for healthy adults.
Behind a bloomin' paywall.
nature.com/articles/s41586-...
You an view several of the diagrams/figures from the article if you scroll down to:
Extended data figures and tables
On this link:
nature.com/articles/s41586-...
And click on each of the links below it.
"Are we treating a lab test or the patient?" Useful Thyroid Tests and the Importance of Looking Beyond the Numbers
Update on inconsistent ferritin results between NHS and Medichecks
