Endocrine Abstracts

Background: Diagnosing endogenous Cushing’s syndrome (CS) is often challenging because of the difficulty in interpreting results of dynamic endocrine tests. One of the recommended initial tests is the measurement of late-night salivary cortisol (LNSaCl). Some articles describe added value of late-night salivary cortisone (LNSaCn) measurements. However, published cut-off values of LNSaCl and LNSaCn vary widely between studies, which may be related to different experimental...

Introduction: Physicians in our hospital notified the laboratory staff of a number of patients at the outpatient clinic with increased free T4 (fT4) concentrations without (complete) suppression of thyroid stimulating hormone (TSH). This phenomenon appeared to occur more frequently following implementation of a new automated fT4 immunoassay. The discordance between fT4 and TSH concentrations may be explained by analytical issues (not further explained here), incorrect referenc...

We report an interference in an immunoassay for aldosterone, which potentially could have led to a wrongful diagnosis and unnecessary surgery. The interference was serendipitously recognized due to a preanalytical error. A 59-year-old female patient with hypertension was referred to the department of endocrinology after an adrenal incidentaloma was detected. Because of her hypertensive history, screening for primary hyperaldosteronism was performed. An elevated aldosterone and...

Objectives: Free thyroxine (fT4) measurements are performed to detect thyroid disorders and monitor treatment. FT4 is measured using automated immunoassays (IAs) which face established analytical challenges due to low serum concentrations in the picomolar range and the precarious equilibrium between free and bound T4 (to thyroid-binding globulin (TBG) and (pre-)albumin). Furthermore, IAs are known to be affected by the composition of the serum sample (matrix-effects), which ca...

Introduction: In patients with ACTH-dependent hypercortisolism, the corticotropin-releasing-hormone (CRH) test and the high dose dexamethasone suppression test (HDDST) can be used to differentiate between pituitary ACTH production (Cushing’s disease) and ectopic ACTH production. The rationale is that a pituitary adenoma will show some response to CRH and ACTH whereas an ectopic source is less responsive to ACTH and CRH. However, there is discussion about the clinical util...

Introduction: Thyroid disorders are generally diagnosed based on thyroid stimulating hormone (TSH) outside the reference interval (RI), and subsequent free thyroxine (FT4) concentrations. Most laboratories do not provide age-specific RIs for TSH and FT4 beyond childhood, although it is known that TSH concentrations vary with age which may be important to take into account. Therefore, we aimed to establish age-specific RIs for TSH and FT4 throughout life using an indirect metho...