Elecsys system

The symptoms and signs of symptomatic hypocalcemia include numbness or tingling around the mouth and fingers, muscle spasms, or cramps in the limbs. Other signs include the Chvostek sign and Trousseau sign. PTH was measured using an electrochemiluminescence immunoassay (Roche Elecsys System, Roche Diagnostics, Mannheim, Germany), and serum calcium was measured by the o-cresolphthalein complexone method (reference values 15–65 pg/mL and 2.0–2.6 mmol/L, respectively, according to the manufacturer’s normative data). Hypoparathyroidism was defined as PTH level below the normal range. PTH < 15 pg/mL has been adopted by some studies [6 (link), 12 (link), 13 (link)]. Normal parathyroid function was defined as PTH > 15 pg/mL without oral calcium or calcitriol replacement therapy. Permanent hypoparathyroidism was defined as postoperative PTH < 15 pg/mL lasting for more than 1 year and requiring oral calcium or calcitriol replacement therapy. The serum magnesium concentration reference value ranges from 0.66 to 1.07 mmol/L, and the serum phosphorus concentration value reference ranges from 0.86 to 1.78 mmol/L.

For the entire cohort, Aβ and total tau concentrations were measured using β-amyloid (1–42) and hTau Ag ELISA tests. Aβ42 and total tau levels were measured on the Roche Elecsys system. These measurements were performed by Clinical Laboratory Improvement Amendments (CLIA)-certified Mayo Clinic Laboratories following manufacturers’ instructions. CSF Aβ42 and total tau cut-offs follow Mayo Clinic reference values: Aβ42 at 1026 pg/ml and total tau cut-off at 238 pg/ml (Hansson et al., 2018 (link)).