Interestingly, the only known study where urinary NfL was measured by SIMOA found no differences between urinary NfL in 93 people with stroke/haemorrhage disease compared with 10 healthy controls when corrected for urinary dilution.108 The form of NfL fragments in urine should be investigated and compared with blood and CSF, to determine if fragments of NfL are important as a urinary ALS biomarker. Here, NEFL is linked to amyotrophic lateral sclerosis.