This article is more than 5 years old. Information may no longer be current.
Clinical judgment is paramount
Some months ago I posted a blog pointing out discordance between levels of thyroid-stimulating hormone and free thyroxine that were making it difficult to make a correct laboratory diagnosis of hyperthyroidism and hypothyroidism. That issue has not been fully resolved but discrepancies seem to have slowed down. Until last week!
My patients have their blood work analyzed at one of several laboratories. One day last week, I received results from four patients that made little sense. Each study had been done at the same lab and each reported a normal value for TSH and a quite high value for free thyroxine (T4). None of those patients had clinical evidence of hyperthyroidism that came close to the lab data.
I took a trip to that lab and, as politely as possible (difficult for me as many colleagues and friends know), I discussed these out-of-whack results with the lab director. I seemed to make little headway and began scheduling thyroid uptake studies to verify my clinical diagnosis.
To my very pleasant surprise, I received a call the next day telling me that the lab personnel had critically reviewed their technology and uncovered a mechanical flaw with the analysis that would have accounted for the high free T4 values. Once the instrument was repaired the lab repeated the assays — now the results were in keeping with the clinical evaluation. I cancelled the uptake studies.
What is the messages here? Clinical judgment is paramount. If the lab data do not match your clinical judgment, do not immediately react and initiate the wrong therapy or order confirmatory or ancillary tests. This is particularly important when confronted with “incidental findings,” whether found on lab tests or imaging studies. Don’t ignore them either — review your clinical material, talk to your lab or radiology colleagues, and together develop a plan to make the most sense out of the findings.
This should be easier in endocrinology than many other disease categories because we deal with close-looped systems: T4 and TSH; calcium and parathyroid hormone; cortisol and adrenocorticotropic hormone; and so on.