PTH and hyperparathyroidism: In this study, we retrieved anonymized data on calcium metabolism parameters assessing the occurrence of subclinical hyperparathyroidism—subclinical nutritional rickets (PTH > 45 pg/mL with normal serum calcium) in 1138 children and adolescents in the post-COVID-19 period (2022, 2023) compared to similar data from our group retrieved in the pre-COVID era (2016–2018) on 3060 patients.