Severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) causes coronavirus disease 2019 (COVID-19), with a clinical outcome ranging from mild to severe, including death. To date, it is unclear why some patients develop severe symptoms. Many authors have suggested the involvement of vitamin D in reducing the risk of infections; thus, we retrospectively investigated the 25-hydroxyvitamin D (25(OH)D) concentrations in plasma obtained from a cohort of patients from Switzerland. In this cohort, significantly lower 25(OH)D levels (p = 0.004) were found in PCR-positive for SARS-CoV-2 (median value 11.1 ng/mL) patients compared with negative patients (24.6 ng/mL); this was also confirmed by stratifying patients according to age >70 years. On the basis of this preliminary observation, vitamin D supplementation might be a useful measure to reduce the risk of infection. Randomized controlled trials and large population studies should be conducted to evaluate these recommendations and to confirm our preliminary observation.

A macro-thyroid-stimulating hormone (macro-TSH) is an infrequent yet noteworthy phenomenon in the thyroid field. A 69-year-old patient presented with persistently elevated thyroid-stimulating hormone (TSH) levels ranging from 30 to 50 mIU/L, paradoxically accompanied by normal thyroid hormone levels and normal thyroid ultrasound, with no findings on pituitary magnetic resonance. Laboratory studies were conducted to investigate potential interferences impacting the accuracy of TSH measurements. After excluding other potential causes, polyethylene glycol (PEG) precipitation technique was used, which led us to the diagnosis of macro-TSH. This result was confirmed through chromatography. Macro-TSH, although rare, emerged as the key contributor to the patient’s unexplained increase in TSH levels. This case highlights the importance of considering macro-TSH as a potential etiology in cases characterized by unexplained TSH elevation, offering insights into diagnostic protocols and expanding our understanding of thyroid function anomalies.