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Thiamine is a crucial cofactor involved in the maintenance of carbohydrate metabolism and participates in multiple cellular metabolic processes within the cytosol, mitochondria, and peroxisomes. Currently, four genetic defects have been described causing impairment of thiamine transport and metabolism: SLC19A2 dysfunction leads to diabetes mellitus, megaloblastic anemia and sensory-neural hearing loss, whereas SLC19A3, SLC25A19, and TPK1-related disorders result in recurrent encephalopathy, basal ganglia necrosis, generalized dystonia, severe disability, and early death. In order to achieve early diagnosis and treatment, biomarkers play an important role. SLC19A3 patients present a profound decrease of free-thiamine in cerebrospinal fluid (CSF) and fibroblasts. TPK1 patients show decreased concentrations of thiamine pyrophosphate in blood and muscle. Thiamine supplementation has been shown to improve diabetes and anemia control in Rogers' syndrome patients due to SLC19A2 deficiency. In a significant number of patients with SLC19A3, thiamine improves clinical outcome and survival, and prevents further metabolic crisis. In SLC25A19 and TPK1 defects, thiamine has also led to clinical stabilization in single cases. Moreover, thiamine supplementation leads to normal concentrations of free-thiamine in the CSF of SLC19A3 patients. Herein, we present a literature review of the current knowledge of the disease including related clinical phenotypes, treatment approaches, update of pathogenic variants, as well as in vitro and in vivo functional models that provide pathogenic evidence and propose mechanisms for thiamine deficiency in humans., (© 2019 SSIEM.)

Thiamine transporter-2 deficiency is caused by mutations in the SLC19A3 gene. As opposed to other causes of Leigh syndrome, early administration of thiamine and biotin has a dramatic and immediate clinical effect. New biochemical markers are needed to aid in early diagnosis and timely therapeutic intervention. Thiamine derivatives were analysed by high performance liquid chromatography in 106 whole blood and 38 cerebrospinal fluid samples from paediatric controls, 16 cerebrospinal fluid samples from patients with Leigh syndrome, six of whom harboured mutations in the SLC19A3 gene, and 49 patients with other neurological disorders. Free-thiamine was remarkably reduced in the cerebrospinal fluid of five SLC19A3 patients before treatment. In contrast, free-thiamine was slightly decreased in 15.2% of patients with other neurological conditions, and above the reference range in one SLC19A3 patient on thiamine supplementation. We also observed a severe deficiency of free-thiamine and low levels of thiamine diphosphate in fibroblasts from SLC19A3 patients. Surprisingly, pyruvate dehydrogenase activity and mitochondrial substrate oxidation rates were within the control range. Thiamine derivatives normalized after the addition of thiamine to the culture medium. In conclusion, we found a profound deficiency of free-thiamine in the CSF and fibroblasts of patients with thiamine transporter-2 deficiency. Thiamine supplementation led to clinical improvement in patients early treated and restored thiamine values in fibroblasts and cerebrospinal fluid., (© The Author (2015). Published by Oxford University Press on behalf of the Guarantors of Brain. All rights reserved. For Permissions, please email: journals.permissions@oup.com.)

Thiamine is an essential cofactor for several important enzymes involved in brain oxidative metabolism, such as the alpha-ketoglutarate dehydrogenase complex (KGDHC), pyruvate-dehydrogenase complex (PDHC), and transketolase. Some investigators reported decreased thiamine-diphosphate levels and decreased activities of KGDHC, pyruvate-dehydrogenase complex and transketolase in the brain tissue of Alzheimer's disease (AD) patients. We measured cerebrospinal (CSF) levels of thiamine-diphosphate, thiamine-monophosphate, free thiamine, and total thiamine, using ion-pair reversed phase high performance liquid chromatography, in 33 patients with sporadic AD and 32 matched controls. The mean CSF levels of thiamine-derivatives did not differ significantly from those of controls, while the mean plasma levels of thiamine-diphosphate, free and total thiamine were significantly lower in the AD-patient group. CSF and plasma thiamine levels were not correlated with age, age at onset, duration of the disease, and scores of the MiniMental State Examination, with the exception of plasma thiamine-diphosphate with MiniMental State Examination (r = 0.41, p < 0.05) in the AD-patients group. CSF and plasma values did not predict dementia progression, assessed with the MiniMental State Examination scores. These results suggest that CSF thiamine levels are not related with the risk for and the progression of AD.

Background: The aims of the present study were: i) to measure levels of the dopamine metabolite homovanillic acid (HVA), the serotonin metabolite 5-hydroxindoleacetic acid (5HIAA) and precursor tryptophan, as well as the noradrenaline metabolite 3-methoxy-4-hydroxyphenylethylene glycol (MHPG) and thiamine in the cerebrospinal fluid (CSF) of patients with Friedreich's ataxia (FA), olivopontocerebellar atrophy (OPCA), and the autosomal recessive spastic ataxia of Charlevoix-Saguenay (ARSAC), as compared with sex- and age-matched control subjects., Patients and Methods: CSF amine related compound levels and thiamine results were compared in 40 FA, 44 OPCA and nine ARSAC patients with those of 94 sex- and age-matched subjects. Neuroimaging (CT scans and single photon emission computed tomographies i.e. SPECT) were carried out in all patients and controls. Genetic studies were conducted on OPCA patients. CSF amine related compounds were measured by high performance liquid chromatography, whereas CSF thiamine levels were measured by a microbiological method., Results: FA patients had significantly lower CSF HVA, 5HIAA and thiamine values than control patients and a trend for lower MHPG levels. In OPCA patients, CSF HVA, MHPG and thiamine values were markedly lower whereas CSF 5HIAA values showed only a trend towards lower levels; in ARSAC patients only thiamine and HVA CSF values were lower than those in control subjects., Conclusion: After presenting the relationships between neurochemical findings on one side, the degree of ataxia, the degree of cerebellar atrophy and the SPECT findings on the other, the authors concluded that replacement and neuroprotective clinical trials in these patients would have to include two or three drugs because the neurotransmitter deficiencies are multiple.

Thiamine is an essential cofactor for several important enzymes involved in brain oxidative metabolism, such as the alpha-ketoglutarate dehydrogenase complex (KGDHC), pyruvate-dehydrogenase complex, and transketolase. The activity of KGDHC is decreased in the substantia nigra or patients with Parkinson's disease (PD). We measured cerebrospinal (CSF) levels of thiamine-diphosphate, thiamine-monophosphate, free thiamine, and total thiamine, using ion-pair reversed phase high performance liquid chromatography, in 24 PD patients and 40 matched controls. The mean CSF levels of thiamine-derivatives did not differ significantly from those of controls, with the exception of lower CSF free thiamine levels in the PD-patient group. PD patients under levodopa therapy had significantly higher CSF thiaminediphosphate and total thiamine than those not treated with this drug. CSF thiamine levels were not correlated with age, age at onset, duration of the disease, scores of the Unified Parkinson Disease Rating Scale of the Hoehn and Yahr staging in the PD group. These results suggest that low CSF free thiamine levels could be related with the risk for PD.

A 24-year-old woman with a large cell anaplastic CD 30-positive T-cell non-Hodgkin's lymphoma (NHL) developed downbeat nystagmus, anisocoria, and oscillopsia. Prior to overt cerebral invasion by NHL, she had a thiamine deficiency with very low thiamine concentrations in the CSF, probably caused by protracted vomiting and increased vitamin B1 consumption by intrathecal tumor cells. We believe that her neurologic symptoms were caused -- at least partly -- by thiamine deficiency, as she reacted well to thiamine supplementation at the beginning of treatment.

Actual therapeutic assays in spinocerebellar ataxias, i.e. in Friedreich's ataxia (FA) and olivopontocerebellar atrophy (OPCA) are discussed in relation to (i) the serotoninergic theory; (ii) the excitotoxic action of glutamate; and (iii) cerebrospinal fluid thiamine deficiency in ataxic patients. Data from the literature show that neurochemical deficiencies arising from cerebellar damage in both FA and OPCA patients are multiple. Assays of replacement and neuroprotective therapeutics with a single drug have produced controversial data or mildly effective results. Consequently, it is hypothesized that a drug cocktail, i.e. L-5-hydroxytryptophan, thiamine and amantadine hydrochloride, would be more beneficial. This cocktail proved to be useful in open studies, improving respiratory disorders in FA patients. More powerful inhibitors of N-methyl-D aspartate receptor channels should be tried initially in animal experiments.

Thiamin, thiamin monophosphate, ascorbic acid, and folic acid were determined in serum and cerebrospinal fluid (CSF) in 31 outpatients who underwent a myelography because of back-pain. All subjects were otherwise healthy. The CSF concentration (mean +/- SD) was 8.6 +/- 3.9 nmol thiamin/L, 16.9 +/- 8.3 nmol thiamin monophosphate/L, 133 +/- 58.8 mumol ascorbic acid/L, and 44.9 +/- 13.2 nmol folic acid/L. The CSF-serum ratio was 2.1 +/- 0.8 for thiamin, 8.3 +/- 4.3 for thiamin monophosphate, 3.0 +/- 1.4 for ascorbic acid, and 3.3 +/- 0.8 for folic acid; the amount in CSF was significantly higher than in serum for each compound. These results support the existence of a saturated transport mechanism of water-soluble vitamins from serum into CSF for thiamin monophosphate, ascorbic acid, and folic acid. However, low CSF concentrations are correlated with low serum concentrations for the three vitamins. High serum concentrations should therefore be advocated to ensure high CSF concentrations.

Blood thiamine levels in ataxia patients were studied. No significant differences were found between 30 patients with Friedreich's ataxia and 29 patients with olivopontocerebellar atrophy (OPCA) compared with control subjects. Both OPCA and Friedreich's ataxia patients presented significantly lower cerebrospinal fluid thiamine levels than their controls (p less than 0.001 and p less than 0.04 respectively). These results, discussed in terms of the high degree of cerebellar atrophy on CT scans in OPCA v Friedreich's ataxia patients, seem to correlate with cerebellar thiamine turnover and content.

Free thiamin and thiamin monophosphate have been found in the cerebrospinal fluid, plasma and in erythrocytes of patients suffering from ataxia of different origins. In erythrocytes, thiamin pyrophosphate was also measured. In a limited number of cases, uptake of 14C-thiamin by erythrocytes was found as well. Controls were hospitalized patients affected by chronic neurological diseases without any clinical sign of thiamin deficiency. The results showed a significant decrease in thiamin and thiamin monophosphate in the cerebrospinal fluid and in the plasma of ataxic subjects, in comparison to controls. In erythrocytes, only thiamin pyrophosphate levels had decreased. The uptake of 14C-thiamin by erythrocytes was similar in both ataxic and control groups. These results were comparable to those observed in thiamin-deficient individuals, like alcoholic patients, and prompted further investigation into thiamin metabolism in these diseases.

Nine 115- to 180-kg, hay-adapted, Holstein steers were fed an experimental diet with added sodium sulfate that induces polioencephalomalacia (PEM). Five calves developed the disease. Thiamine concentrations in blood, CSF, brain, and liver were not indicative of thiamine deficiency. The odor of hydrogen sulfide in eructated rumen gas was associated with the onset of PEM. Sulfide concentrations in rumen fluid were measured 1 or 2 times a week by 2 techniques. Sulfide concentrations progressively increased in all 9 calves after the feeding of the PEM-inducing diet commenced. The highest concentrations coincided with the onset of clinical signs of PEM and were significantly higher in the calves that developed PEM than in those that did not. This suggests that PEM can result from sulfide toxicosis following excess production of sulfide in the rumen.

We determined pediatric age-specific normative ranges for total, phosphorylated, and nonphosphorylated thiamin in whole blood (n = 323) and cerebrospinal fluid (CSF; n = 208). Whole-blood total thiamin decreased from 258 +/- 63 (mean +/- SD; age 0-3 mo group) to 214 +/- 44 nmol/L (age 3-12 mo group) in the first year of life and was stable at 187 +/- 39 nmol/L after 12 mo of age. The overall decline in whole-blood total thiamin was mainly due to a drop in phosphorylated thiamin, the biologically active form. Mean CSF total thiamin decreased from 135 +/- 42 (age 0-9-mo group) to 107 +/- 34 nmol/L (age 9-18-mo group) in the first 1.5 y of life and was stable at 84 +/- 51 nmol/L thereafter. This overall decline was due initially to a drop in nonphosphorylated thiamin and later to a drop in phosphorylated thiamin. The changes in whole blood and CSF occurred independently and probably represent metabolic and neurological maturation of the infant. Whole-blood total and phosphorylated thiamin concentrations were lower in blacks only after pubarche. Age-specific norms should be used for determining the thiamin status in infancy because thiamin concentrations are significantly higher in the first few months of life.

A total of 157 epileptic patients were studied with respect to (1) biogenic amine precursors and metabolites in the CSF, (2) levels of folate and thiamine in the blood and CSF, (3) length of treatment with phenytoin (PHT), (4) PHT intoxication, (5) CNS atrophy. Alterations in CSF amine metabolite levels were related primarily to PHT intoxication, and low CSF folate and thiamine levels, but not to length of treatment or CNS atrophy. PHT intoxication increased CSF 5-hydroxyindoleacetic acid (5HIAA). Low folate levels were associated with decreased CSF 5HIAA and homovanillic acid, while low thiamine levels were associated with decreased CSF 5HIAA and 3-methyoxy-4-hydroxyphenylethylene glycol. It remains to be seen to what extent these alterations in biogenic amine metabolism, mediated by low CNS vitamin levels, also lead to deficits in cerebral function.

A series of children with Leigh's disease had normal hepatic pyruvate carboxylase activity, increased cerebral thiamine diphosphate, and decreased cerebral thiamine triphosphate. These thiamine esters were normal in liver. The author suggests that the histologic changes of Leigh's disease, as well as the similar changes of Wernicke's disease, could be due to a deficiency of cerebral thiamine triphosphate.

Free thiamin and thiamin monophosphate levels were determined by an electrophoretic fluorometric micromethod in plasma and CSF of patients with amyotrophic lateral sclerosis (ALS), alcoholics, and controls. In plasma of patients with ALS as well as in plasma and CSF of alcholics, both thiamin and thiamin monophosphate concentrations were decreased so that the thiamin-thiamin monophosphate (T/TMP) ratio remained unchanged compared with that of controls. In CSF of patients with ALS, however, thiamin monophosphate values decreased much more than thiamin levels, so that the T/TMP ratio was significantly increased. The selective impairment of thiamin monophosphate production by nerve cells is likely to result from the reduction of the activity of thiamin pyrophosphatase, an enzyme synthetized and highly concentratd in the Golgi complex. Thiamin pyrophosphatase is known to diminish in ALS as well as in experimental motor neuronal degeneration or axotomy. Thus, the T/TMP ratio could be taken as an index of the impairment of neuronal protein synthesis in ALS.

Thiamine (T) and thiamine monophosphate (TMP) levels were determined by an electrophoretic fluorometric method in the CSF of patients with typical sporadic ALS (50 cases), in other motor neuron diseases (MND) (14 cases) and in patients with upper and/or lower motor neuron lesions of varying origin (disseminated sclerosis, polyneuropathy, spondylotic myelopathy). T/TMP ratio was greater than or equal to 1 in a high percentage of patients with typical sporadic ALS (94%), in 35.7% of cases with other MND, while it was below 1 in the all other patients. The decrease of TMP with the inversion of the T/TMP ratio is a finding highly specific to typical sporadic ALS.

Total thiamine (free thiamine and thiamine phosphates) transport into the cerebrospinal fluid (CSF), brain, and choroid plexus and out of the CSF was measured in rabbits. In vivo, total thiamine transport into CSF, choroid plexus, and brain was saturable. At the normal plasma total thiamine concentration, less than 5% of total thiamine entry into CSF, choroid plexus, and brain was by simple diffusion. The relative turnovers of total thiamine in choroid plexus, whole brain, and CSF were 5, 2, and 14% per h, respectively, when measured by the penetration of 35S-labeled thiamine injected into blood. From the CSF, clearance of [35S]thiamine relative to mannitol was not saturable after the intraventricular injection of various concentrations of thiamine. However, a portion of the [35S]thiamine cleared from the CSF entered brain by a saturable mechanism. In vitro, choroid plexuses, isolated from rabbits and incubated in artificial CSF, accumulated [35S]thiamine against a concentration gradient by an active saturable process that did not depend on pyrophosphorylation of the [35S]thiamine. The [35S]thiamine accumulated within the choroid plexus in vitro was readily released. These results were interpreted as showing that the entry of total thiamine into the brain and CSF from blood is regulated by a saturable transport system, and that the locus of this system may be, in part, in the choroid plexus.

In three out of five patients with low cerebrospinal fluid thiamine concentrations, the 5-hydroxyindoleacetic acid (5HIAA) values also were low. All patients received thiamine replacement therapy; they underwent a second lumbar puncture after 13, 6, 7, 5 and 45 days of treatment. In all patients blood and cerebrospinal fluid thiamine values rose after treatment. In those patients with initially low CSF 5HIAA, thiamine treatment increased 5HIAA markedly.

Thiamine and folate levels in blood and cerebrospinal fluid (CSF) were determined by microbiological assays in 23 control subjects and 11 phenytoin-treated epileptics. There was no significant difference between the two groups for serum and CSF folate levels. There was, however, a statistically significant difference between the groups for both whole blood thiamine and CSF thiamine levels. Epileptic patients being treated with phenytoin had lower values than control subjects.

Whole blood hemolysed by freezing, serum, cerebrospinal fluid, and milk of human origin were deproteinized by perchloric acid. Thiamine pyrophosphate and thiamine monophosphate were hydrolysed to thiamine by acid phosphatase. Chromatography was performed on C18-coated silica using an n-octanesulfonate containing mobile phase methanol-aqueous citrate buffer pH 4.0 (45:55, v/v). In a post-column reaction K3Fe(CN)6 is used to oxidise thiamine to thiochrome, which is detected by fluorometry. Two ml blood is needed. The minimum detectable amount is 60 femtomol of thiamine. The intra-assay coefficient of variation (C.V.) is 2.3% and the inter-assay C.V. is 3.9%. The recovery of added thiamine pyrophosphate to blood samples was 98.7%. The reference range was found to be 88-157 nmol/1 whole blood. Examples of the analysis of cerebrospinal fluid, serum and milk are given.

With a specific and sensitive electrophoretic-fluorometric method, thiamin was found in the cerebro-spinal fluid of different mammals both in free and phosphorylated form, monophosphate being the only thiamin phosphoric ester. In humans, its amount was about 60% of total thiamin. Alcoholism greatly lowered total thiamin content, affecting both thiamin forms.