Inversion of T/TMP ratio in ALS: a specific finding?

Area of Science:

• Neuroscience
• Biochemistry
• Clinical Neurology

Background:

• Thiamine (Vitamin B1) and its primary metabolite, thiamine monophosphate (TMP), play crucial roles in neuronal function.
• Altered thiamine metabolism has been implicated in various neurological disorders, but its specific role in Amyotrophic Lateral Sclerosis (ALS) requires further elucidation.

Purpose of the Study:

• To investigate the levels of thiamine (T) and thiamine monophosphate (TMP) in the cerebrospinal fluid (CSF) of patients with typical sporadic ALS.
• To determine the diagnostic utility of the T/TMP ratio in differentiating ALS from other motor neuron diseases (MND) and neurological conditions affecting motor pathways.

Main Methods:

• Cerebrospinal fluid (CSF) samples were collected from patients diagnosed with typical sporadic ALS, other MND, and various conditions causing upper and/or lower motor neuron lesions.
• Thiamine (T) and thiamine monophosphate (TMP) levels were quantified using a sensitive electrophoretic fluorometric method.
• The ratio of T to TMP (T/TMP ratio) was calculated for each patient.

Main Results:

• A high percentage of patients (94%) with typical sporadic ALS exhibited a T/TMP ratio greater than or equal to 1.
• In contrast, only 35.7% of patients with other MND showed a T/TMP ratio of 1 or higher.
• All patients with other neurological conditions affecting motor neurons had a T/TMP ratio below 1.

Conclusions:

• The decrease in TMP levels, leading to an inverted T/TMP ratio (≥1), is a highly specific biomarker for typical sporadic ALS.
• This biochemical marker may aid in the differential diagnosis of ALS, distinguishing it from other motor neuron diseases and neurological disorders.