Inappropriate lab testing is a global healthcare problem. It is estimated that 10-30% of laboratory tests are unnecessary [1, 2]. Not only is this a waste of money, but more importantly inappropriate testing can lead to unnecessary physical or physiological harms to the patient [3]. Inappropriate tests can be defined as those ordered in contradiction to practice guidelines, tests ordered for patients without signs or symptoms of disease (low pretest probability), tests that are repeated too frequently, or tests that simply will not change clinical management [1-3]. The causes of inappropriate testing include lack of awareness, practicing defensive medicine that entails extensive testing to rule out unlikely conditions, and pressures from patients to order certain lab tests [4]. Inappropriate testing is also rooted in the inability to easily cancel tests and routine lab test profiles that contain large numbers of redundant tests [4]. Aside from raising awareness to inappropriate testing, effective quality improvement (QI) requires the development of implementation strategies through a collaboration between clinicians and laboratory professionals.

Plan-Do-Study-Act (PDSA) is a QI strategy that methodically reduces inappropriate testing and can quantify the impact of QI initiatives [5]. The article by Taher et al. [6] addressed the problem of unnecessary thyroid testing using the PDSA framework. Applying two consecutive PDSA cycles allowed for a decrease in unnecessary free T4 (fT4) and free T3 (fT3) testing by 39% and 47%, respectively. The first PDSA cycle implemented a reflexive testing algorithm designed to reflex fT4 and fT3 only when TSH was low, and fT4 when TSH was high (as defined by the laboratory reference ranges). These reflex cutpoints were validated in a previous study [7] that determined optimal cutpoints based on sensitivity and specificity. The outcome of the first PDSA cycle was a reduction in fT4 and fT3 testing by 24% and 18% respectively. After careful study of the data, and solicited feedback from our physicians of various departments, we realized that forcing all thyroid hormone testing through this algorithm was causing some unnecessary testing to occur. Patients with primary hypothyroidism on levothyroxine replacement would only require TSH testing, yet our algorithm would add-on fT4 and fT3 testing if the TSH was abnormal. Furthermore, fT3 was unnecessary in situations of low TSH and abnormal fT4. Therefore, in the second PDSA cycle, a “TSH only” ordering option was implemented, and the reflex algorithm was refined such that fT3 was only reflexed when fT4 was normal and TSH was low. The outcome of the second PDSA cycle included a further reduction in fT3 and fT4 by 29% and 16%, respectively. Not only were the outcomes better after the second PDSA, but physician and patient satisfaction was vastly improved. The take home message here applies to all utilization projects: the initial change idea will often not be the best. It is important to study the outcomes from the initial change, ensure the change is an improvement, and then further optimize it to get the best overall outcome.

This study utilized several solutions to combat thyroid hormone overutilization including computerized reflexive testing, assigning privileged ordering providers such as endocrinologists and neurosurgery, high level approval for clinicians requesting free thyroid hormones with normal TSH and computerized decision support as in the addition of the “TSH only” option. Continuous improvement and soliciting physician feedback were shown as necessary, since optimal reduction was attained only after the second PDSA cycle.


  1. C.W.C. Canadian Institute for Health Information, Unnecessary Care in Canada, (2017).

  2. R.E. Thomas, B.L. Croal, C. Ramsay, M. Eccles, J. Grimshaw, Effect of enhanced feedback and brief educational reminder messages on laboratory test requesting in primary care: a cluster randomised trial, Lancet 367(9527) (2006) 1990-6.

  3. S. Brownlee, K. Chalkidou, J. Doust, A.G. Elshaug, P. Glasziou, I. Heath, S. Nagpal, V. Saini, D. Srivastava, K. Chalmers, D. Korenstein, Evidence for overuse of medical services around the world, Lancet 390(10090) (2017) 156-168.

  4. M. Salinas, E. Flores, M. López-Garrigós, C. Leiva-Salina, Laboratory test inappropriateness: lessons revisited and clarified in seven questions, Journal of Laboratory and Precision Medicine 3(4) (2018).

  5. e.a. Langley GL, The Improvement Guide: A Practical Approach to Enhancing Organizational Performance (2009).

  6. J. Taher, D.R. Beriault, D. Yip, S. Tahir, L.K. Hicks, J.A. Gilmour, Reducing free thyroid hormone testing through multiple Plan-Do-Study-Act cycles, Clin Biochem 81 (2020) 41-46.

  7. J. Taher, D. Brinc, J.A. Gilmour, D.R. Beriault, Validating thyroid-stimulating hormone (TSH) reflexive testing cutpoints in a tertiary care institution, Clin Chem Lab Med 58(1) (2019) e11-e13.