Potential Risks and Benefits of Desiccated Thyroid Extract for the Treatment of Hypothyroidism: A Systematic Review.

Background: Desiccated thyroid extract (DTE) is no longer recommended for the treatment of hypothyroidism but is still in use. This review aimed to summarize the available literature on treatment with DTE in adult patients with hypothyroidism. Methods: The search was conducted up until January 6, 2024, in six electronic databases. Two reviewers independently screened all the search results. The retrieved studies compared DTE treatment with levothyroxine or combination therapy with liothyronine and levothyroxine. The primary outcome was quality of life (QoL), and the secondary outcomes included symptoms, treatment preference, adverse effects, thyroid hormone levels, thyroid autoantibodies, cardiovascular measures, and gene polymorphisms in deiodinase enzymes. Results: In the qualitative synthesis, we included nine nonrandomized studies of interventions (NRSIs), two randomized clinical trials (RCTs), and three case reports. The overall quality of evidence was moderate to very low for the various outcomes. The RCTs found no difference between treatments regarding QoL and symptom score assessments. In the NRSIs, symptom and QoL assessments were in favor of DTE. The included studies indicated that DTE may cause an increase in heart rate, lower body weight, and lower high-density lipoprotein compared with other treatment regimens, but results were conflicting. Conclusions: Most studies of DTE treatment are hampered by an inferior design, and data on long-term effects and side effects are lacking. Two RCTs could not demonstrate any difference in QoL or symptom scores when comparing DTE with other thyroid hormone substitutions. Future trials of DTE in patients with hypothyroidism should be based on adequate study designs, validated measures of QoL, patients with reduced QoL, and the assessment of biomarkers reflecting long-term adverse effects.

Macro-TSH: A Diagnostic Challenge.

INTRODUCTION: Analytical problems should be considered in case of a discrepancy between the results of biochemical tests and the clinical findings. Macro-hormones often artefactually elevate biochemical tests. CASE PRESENTATION: A young male was referred with persistently elevated TSH (148 mIU/L) measured by a sandwich electrochemiluminescence immunoassay, ECLIA (Cobas; Roche, Basel, Switzerland). The patient's complaints were unspecific, and he appeared clinically euthyroid. The plasma levels of free T4 and free T3 were within the normal range, thyroid autoantibodies were negative, and thyroid ultrasonography was normal. During a short trial of thyroid hormone substitution, the level of TSH decreased to near-normal levels, but hyperthyroid symptoms emerged. TSH analysed by a different immunoassay (Architect; Abbott, Chicago, IL, USA) yielded similar results. In addition, serial dilutions were performed showing linearity, without detection of heterophilic antibody interference. Gel filtration chromatography confirmed the presence of macro-TSH. CONCLUSION: The patient harboured macro-TSH, which is a rare condition. The complex binding of TSH to other plasma proteins, most often immunoglobulins, results in elevated plasma TSH. However, the biologically active fraction of TSH is normal, reflected by clinical and biochemical euthyroidism.