Serum calcium levels are associated with cognitive function in hypoparathyroidism: a neuropsychological and biochemical study in an Italian cohort of patients with chronic post-surgical hypoparathyroidism

Purpose: Hypoparathyroidism (HypoPT) is a rare endocrine disease and conventional therapy is based on calcium and vitamin D analogues. Conventional therapy does not restore calcium homeostasis and patients complain with neuropsychological symptoms, which have been evaluated with nonspecific self-administered questionnaires. This study aims to evaluate cognitive functions of patients with chronic post-surgical (PS)-HypoPT compared to a control population, using a standardized neuropsychological approach and evaluating the relationship with serum calcium (Alb-Ca). Methods: Observational, monocentric study on 33 patients with PS-HypoPT and 24 controls, in whom biochemical testing and a standardized neuropsychological assessment by a trained psychologist were performed. Results: In patients with PS-HypoPT, low Alb-Ca correlated with a worse performance on semantic memory abilities and executive function, as suggested by a significant inverse correlation between Alb-Ca and Trail Making Test A (TMT-A) scores (r = - 0.423; p = 0.014) and by a positive correlation with Semantic Fluency Test scores (SF)(r = 0.510; p = 0.002). PS-HypoPT patients with Alb-Ca <= 8.9 mg/dl had a significantly lower test performance compared with PS-HypoPT patients with Alb-Ca > 8.9 mg/dl, both at the TMT-A test (mean score: 34.53-18.55; p < 0.0001) and at SF test (mean score: 41.94-48.68; p = 0.01) and also a significantly lower test performance compared with control patients' group at TMT-A (mean score: 34.53-25.5; p = 0.0057). Conclusions: Patients with chronic PS-HypoPT in conventional therapy do not show a severe cognitive impairment; however, cognitive functions namely visuo-spatial attention, executive function and semantic memory appear to be modulated by Alb-Ca and impaired by its low levels.