Update on therapeutic use of levothyroxine for the management of hypothyroidism during pregnancy.

Hypothyroidism is a relatively common finding during pregnancy. This may be due either to the presence of existing thyroid disease and/or to the increased demands that pregnancy places the thyroid gland to provide thyroid hormones for the mother and the developing fetus. There is no doubt that overt hypothyroidism is associated strongly with adverse pregnancy outcomes, including miscarriage. Meta-analyses show that thyroid hormone replacement with levothyroxine (LT4) reduces the risk of adverse pregnancy outcomes in the setting of overt hypothyroidism. Accordingly, management guidelines in this area are unanimous in recommending intervention with to control the level of thyrotropin (TSH) to below 2.5 µIU/mL. The evidence for an adverse impact of subclinical hypothyroidism (SCH) on pregnancy outcomes is less clear, although meta-analyses suggest that SCH reduces the chance of a successful pregnancy outcome. Guidelines also support intervention for some patients with SCH, particularly where TSH is high (>10 µIU/mL), or where TSH is above its trimester-specific reference range in a woman with thyroid autoimmunity (giving LT4 to euthyroid women with thyroid autoimmunity is not supported). Real-world evidence suggests that hypothyroidism in pregnancy is often overlooked or that LT4 is not given appropriately to gain tight control of TSH. More research is needed to identify the barriers to optimal thyroid care with LT4 at this crucial time.

Subclinical hypothyroidism, outcomes and management guidelines: a narrative review and update of recent literature.

Subclinical hypothyroidism (SCH) is diagnosed when serum thyroid stimulation hormone (thyrotropin; TSH) levels are above the reference range, accompanied by levels of free thyroxine within its reference range. The management of SCH remains a diagnostic and therapeutic challenge despite many years of research relating to its epidemiology, aetiology, effectiveness of treatment and safety. European Thyroid Association (ETA) guidelines for the management of SCH were published almost a decade ago. This narrative review summarizes the clinical literature relating to SCH and outcomes since the publication of these guidelines. Clinical evidence emerging during the previous decade generally supports the view that SCH is associated with adverse outcomes to an extent that is intermediate between euthyroidism and overt hypothyroidism although evidence that treatment with thyroid hormone replacement is beneficial is lacking. Accordingly, the rationale for the recommendations for intervention in the ETA guidelines based on the age of the patient, level of serum TSH, symptoms and comorbidities remains valid today.

A novel point-of-care device accurately measures thyrotropin in whole blood, capillary blood and serum.

OBJECTIVES: Point-of-care (POC) measurement of thyrotropin (TSH) may facilitate prompt diagnosis of thyroid dysfunction. We evaluated the analytical performance of a new POC TSH assay (Wondfo). METHODS: TSH measurements were made from 730 consecutive, unselected subjects in an outpatient setting, using Wondfo in whole blood, capillary blood and serum or automated reference equipment (serum only). RESULTS: TSH measurements were user-independent. Total intra-and inter-assay variation (CV%) was 12.1 and 16.2%, respectively. Total CV% was 10.6-22.6% and 14.5-21.6% in serum and whole blood, respectively. Linearity was very good. Recovery rate was 97-127%. Prolongation of incubation time increased TSH results of 12% (13%) and 33% (35%) after 2 and 5 additional minutes in serum (blood), respectively. When measured simultaneously in two Wondfo devices, the slope of the regression line was 1.03 (serum) and 1.02 (blood), with Spearman's correlation of 0.99 for both. TSH measurements between Wondfo and reference correlated strongly (r=0.93-0.96), though TSH measurements were lower with Wondfo (slopes of plots of measurements made using the two devices were 0.94 [serum vs. serum]; 0.83 [whole blood vs. serum] and 0.64 [capillary blood vs. serum]). Depending on sample material, TSH in capillary blood was lower vs. whole blood (slope: 0.82) and for whole blood vs. serum (Wondfo and reference method; slope: 0.69 and 0.83). Total haemolysis, but not elevated bilirubin or lipemia, disrupted TSH measurement. CONCLUSIONS: The Wondfo system was straightforward to use without need for specialist technicians and demonstrated analytic performance suitable for clinical use for the diagnosis of thyroid dysfunction.