Kamal W, et al. - In this investigation involving 958 patients, researchers sought to validate the International Classification of Diseases - 10th revision (ICD-10) diagnosis of hypoparathyroidism in the Swedish National Patient Register. Patients with ICD-10 diagnosis of hypoparathyroidism were included in the Swedish National Patient Register between 2004 and 2016. A total of 120 randomly selected medical records were reviewed and 109 cases were confirmed. This leads to an overall positive predictive value of 91%. In the Swedish National Patient Register, the validity of the ICD-10 diagnosis of hypoparathyroidism is high and the register is a trusted source for further study. There is a chance of miscoding when assigning the medical records to an ICD-code. They encourage physicians to be aware of this risk, particularly the risk of mix-ups with the more common diagnosis of hyperparathyroidism.