Search

Thyroid function tests (TFTs) are routinely requested by general practitioners (GPs) in the clinical biochemistry laboratory. Hypothyroxinaemia (low fT4) accompanied by TSH within the reference interval (RI) is a discordant pattern which is seen commonly in non-thyroidal illness and also as result of medications. Hypopituitarism is a lot rarer, but a serious condition the laboratory does not want to miss.All thyroid hormone samples from primary care meeting the discordant case definition under investigation [fT4<10 pmol/L and TSH within RI (0.3–4.2 mU/L)] had partial anterior pituitary profiles [PAPP (cortisol, oestradiol/testosterone, prolactin, gonadotrophins)] added as reflex tests and results interpreted by a chemical pathologist. From January to June 2023, we conducted structured interviews with the requesting GPs, and, where indicated, requested repeat samples for full anterior pituitary profile [FAPP (PAPP, growth hormone (GH) and insulin-like growth factor 1 (IGF-1)]. We also reviewed the laboratory records of patients with previously known hypopituitarism to determine their fT4 and TSH values at diagnosis.Over the 6 months 41,487 GP TFTs were requested; 54 (0.13%) fitted the discordant case definition and had PAPP reflexed. 13 FAPPs were requested. We identified 3 cases of hypopituitarism. The number of additional tests required to diagnose 1 case of hypopituitarism was 129. In 74% of reflex-tested cases, there was a plausible explanation for the TFT pattern (medications, known thyroid dysfunction, non-thyroidal illness, pregnancy).This study highlights the importance of medical liaison and early intervention in a biochemistry laboratory in identifying cases of unsuspected hypopituitarism. [ABSTRACT FROM AUTHOR]

In recent years, the short Synacthen test (SS) has become the most widely used test to assess adrenal reserve. Despite its frequent use, there are still several areas related to the short Synacthen test (SST), which have no consensus including the optimum sampling times, that is, whether a 60 min post-Synacthen administration cortisol is necessary or not.Methodology: We performed a retrospective data analysis of 492 SSTs performed on adult patients in a tertiary referral teaching hospital in Ireland. The SSTs were performed in the inpatient and outpatient setting and included patients across all medical disciplines and not exclusively to the endocrinology department.Results: 313 patients had 0, 30 and 60 min samples available for analysis. A total of 270/313 (82%) were deemed to pass the test, that is, cortisol ≥500 nmol/L at both 30 and 60 min. Of the 313 patients, 19 (6%) patients had an indeterminate response, cortisol <500 nmol/L at 30 min, but rising to ≥500 nmol/L on the 60 min sample. Of these 19 patients, only 9/19 patients had a serum cortisol level at 30 min <450 nmol/L, requiring clinical treatment with glucocorticoid replacement. All 24/313 (8%) patients who had insufficient responses at 60 min were also insufficient at 30 min sampling. No individuals passed (≥500 nmol/L) at 30 min and then failed (<500 nmol/L) at 60 min.Conclusion: Using the 30 min cortisol sample post-Synacthen administration alone identifies clinically relevant adrenal insufficiency in the majority of cases. A small subset of patients have a suboptimal response at 30 min but have a 60 min cortisol concentration above the threshold for a pass. Data regarding the long-term outcomes and management of such patients are lacking and require further study. [ABSTRACT FROM AUTHOR]