KL and Alzheimer disease: Within the AD group, the median concentration of Klotho in CSF decreased with disease severity, from 1188.1 pg/mL (range, 756.3-1810.3 pg/mL) in the AD-MCI group to 1073.3 pg/mL (range, 698.2-1661.4 pg/mL) in the AD-dementia group.