1st order laboratory parameters – obligatory laboratory tests.
- Small blood count
- Differential blood count
- Creatine kinase (CK, CK-MB) – may be elevated.
- Electrolytes – calcium, magnesium, sodium, potassium, phosphates, chloride.
- Inflammatory parameters – CRP (C-reactive protein) or ESR (erythrocyte sedimentation rate).
- Liver parameters – alanine aminotransferase (GPT), aspartate aminotransferase (GOT).
- Fasting glucose (fasting blood glucose), if necessary oral glucose tolerance test (oGTT).
- Thyroid parameters – TSH, fT3, fT4
- Serum protein and immunoelectrophoresis.
- Vitamin B12 (methylmalonic acid, homocysteine)
- Neurofilament light chain proteins (NFL; neurofilament light chain) in serum [exceeding a diagnostic threshold → ALS is considered likely].
Laboratory parameters 2nd order – depending on the results of the history, physical examination and the obligatory laboratory parameters – for differential diagnostic clarification.
- ANA (antinuclear antibodies), anti-DNA, anti-Hu, anti-MAG, anti-AchR, anti-MU.
- Angiotensin converting enzyme (ACE).
- Hexosaminidase A and B
- CSF puncture (collection of cerebrospinal fluid by puncture of the spinal canal) for CSF diagnosis – for differential diagnosis.
- Muscle and nerve biopsy – especially in case of atypical manifestation (atypical occurrence) to delineate metabolic, immunologic, and neoplastic causes (neoplasia, i.e., neoplasms)
- Muscle biopsy reveals neurogenic degeneration of II-A fibers and compensatory hypertrophy (enlargement of a tissue) of muscle fibers. The hypertrophy maintains the power output until approximately 50% of the muscle fibers are affected by atrophy. Consequently, muscle strength in ALS patients does not decline until the advanced stage.
- Serology (e.g., borrelia, syphilis (lues), HIV), antibodies against K+ channels.
- If necessary, blood gas analysis (BGA)
