Table 2 Summary of Alzheimer's Biomarkers Standardization Initiative recommendations for Alzheimer's disease biomarker testing
Alzheimer's Biomarkers Standardization Initiative recommendations | ||
|---|---|---|
1 | Computed tomography or MRI performed before LP | LP should not be performed in cases where there is high intracranial pressure or where there is a mass lesion in the brain |
2 | Concomitant medication | LP should not be performed in patients treated with anticoagulants (for example, warfarin). Treatment with platelet aggregation inhibitors is not a contraindication |
3 | Diurnal variation | No diurnal variation |
4 | CSF gradient/volume | No gradient observed. No requirement for a certain fraction. Minimum volume of 1.5 ml |
5 | Meal consumption | No need for fasting |
6 | Position | LP may be performed with the patient either sitting or lying down. The position of the patient does not affect the results |
7 | Location | Vertebral body L3 to L5. The incision point of the needle (L3 to L4 or L4 to L5) does not affect the results |
8 | Disinfection/anesthesia | Disinfection will reduce the risk of local infection. Local anesthetics introduce a risk of adverse effects, but can be given to patients who worry about local pain during LP |
9 | Needle | Use a small diameter (0.7 mm and 22 G), preferably nontraumatic needle. A small-gauge needle will make a smaller hole in the dura, aiding healing, and an atraumatic needle will reduce the chance of blood contamination in the CSF |
10 | Rest | Leave the patient to rest for half an hour after LP. Prolonged bed rest or other procedures will not influence the risk of post-LP headache |
11 | Tubes and aliquotation (type, volume, homogeneity) | Each laboratory should use the same polypropylene tube. Glass or polystyrene tubes should in no circumstances be used. Tubes of the smallest volume should be used, and these should be filled to at least 50% of their volume |
12 | Documentation of sampling/aliquotation | It is important to have carefully recorded and validated details concerning each stored sample so that any investigator when using these samples has a precise history of the sample |
|  | Centrifugation (speed and temperature) | Centrifugation only required for visually hemorrhagic samples. Centrifuge as soon as possible - within 2-hours of LP (on site or at nearest laboratory). Speed has no effect; however, recommend 2,000 × g for 10-minutes at room temperature (controlled) |
13 | Time and temperature before storage | Samples may be sent by regular post (transport 5 days). |
14 | Method of freezing (liquid nitrogen, dry ice, slow freezing at -20°C or -80°C | Freezing at -80°C for storage. No difference between methods of freezing |
15 | Length of storage (when frozen) | Storage at -20°C for less than 2 months. Note: no evidence of any effect for up to 2 years at -80°C. |
16 | Number of freeze/thaw cycles | Limit the number of freeze/thaw cycles to one or two |
17 | Interfering substances (hemolysis) | Traumatic LP: Discard first 1 to 2 ml. Samples with an erythrocyte count of 500/ml should not be used without centrifugation |