Test Catalog

Test ID: TDP    
Thiamine (Vitamin B1), Whole Blood

Useful For Suggests clinical disorders or settings where the test may be helpful

Assessment of thiamine deficiency


Measuring thiamine levels in patients with behavioral changes, eye signs, gait disturbances, delirium, and encephalopathy; or in patients with questionable nutritional status, especially those who appear at risk and who also are being given insulin for hyperglycemia

Clinical Information Discusses physiology, pathophysiology, and general clinical aspects, as they relate to a laboratory test

Thiamine (vitamin B1, thiamin) is an essential vitamin required for carbohydrate metabolism, brain function, and peripheral nerve myelination. Thiamine is obtained from the diet. Body stores are limited and deficiencies can develop quickly. The total thiamine pool in the average adult is about 30 mg. An intake of 0.5 mg per 1,000 kcal per day is needed to maintain this pool. Due to its relatively short storage time, marginal deficiency can occur within 10 days and more severe deficiency within 21 days if intake is restricted.


Approximately 80% of all chronic alcoholics are thiamine deficient due to poor nutrition. However, deficiency also can occur in individuals who are elderly, have chronic gastrointestinal problems, have marked anorexia, are on cancer treatment, or are receiving diuretic therapy.


The signs and symptoms of mild-to-moderate thiamine deficiency are nonspecific and may include poor sleep, malaise, weight loss, irritability, and confusion. Newborns breast fed from deficient mothers may develop dyspnea and cyanosis; diarrhea, vomiting, and aphonia may follow. Moderate deficiency can affect intellectual performance and well-being, despite a lack of apparent clinical symptoms.


Severe deficiency causes congestive heart failure (wet beriberi), peripheral neuropathy (dry beriberi), Wernicke encephalopathy (a medical emergency that can progress to coma and death), and Korsakoff syndrome (an often irreversible memory loss and dementia that can follow). Rapid treatment of Wernicke encephalopathy with thiamine can prevent Korsakoff syndrome. Symptoms of dry beriberi include poor appetite, fatigue, and peripheral neuritis. Symptoms of wet beriberi include cardiac failure and edema. Patients with Wernicke encephalopathy present with behavior change (confusion, delirium, apathy), diplopia (often sixth nerve palsies), and ataxia. A late stage, in which the patients may develop an irreversible amnestic confabulatory state, is referred to as the Wernicke-Korsakoff syndrome.


The response to thiamine therapy in deficient patients is usually rapid. Thiamine deficiency is a treatable, yet underdiagnosed, disorder in the United States. A heightened level of awareness of the possibility of thiamine deficiency is necessary to identify, intervene, and prevent thiamine deficiency's dire consequences. It appears that no conditions are directly attributable to thiamine excess and that thiamine administration is safe except in extremely rare cases of anaphylaxis from intravenous thiamin.


Whole blood thiamine testing is superior to currently available alternative tests for assessing thiamine status. Serum or plasma thiamine testing suffers from poor sensitivity and specificity, and less than 10% of blood thiamine is contained in plasma. Transketolase determination, once considered the most reliable means of assessing thiamine status, is now considered an inadequate method. The transketolase method is an indirect assessment. Since transketolase activity requires thiamin, decreased transketolase activity is presumed to be due to the decrease of thiamin. However, the test is somewhat nonspecific, as other factors may decrease transketolase activity. Transketolase is less sensitive than liquid chromatography-tandem mass spectrometry (LC-MS/MS), has poor precision, and specimen stability concerns.

Reference Values Describes reference intervals and additional information for interpretation of test results. May include intervals based on age and sex when appropriate. Intervals are Mayo-derived, unless otherwise designated. If an interpretive report is provided, the reference value field will state this.

70-180 nmol/L

Interpretation Provides information to assist in interpretation of the test results

Values for thiamine diphosphate of less than 70 nmol/L are suggestive of thiamine deficiency.

Cautions Discusses conditions that may cause diagnostic confusion, including improper specimen collection and handling, inappropriate test selection, and interfering substances

Vitamin supplementation and nonfasting specimens may result in elevated thiamine diphosphate concentrations.

Clinical Reference Recommendations for in-depth reading of a clinical nature

1. Naidoo DP, Bramdev A, Cooper K: Wernicke's encephalopathy and alcohol-related disease. Postgrad Med J 1991;67;978-981

2. Herve C, Beyne P, Letteron PH, Delacoux E: Comparison of erythrocyte transketolase activity with thiamin and thiamin phosphate ester levels in chronic alcoholic patients. Clin Chim Acta 1995;234:91-100

3. Majumdar SK, Shaw GK, O'Gorman P, et al: Blood vitamin status (B1, B2, B6, folic acid, and B12) in patients with alcohol liver disease. Int J Vitam Nutr Res 1982;52:266-271

4. Ball GFM: Vitamins: Their role in the human body. Oxford, Blackwell Publishing, 2004, pp 273-288

5. Brin M: Erythrocyte as a biopsy tissue for functional evaluation of thiamin adequacy. JAMA 1964;187:762-766

6. Roberts NB. Taylor A. Sodi R: Chapter 37 Vitamins and Trace Elements. In Tietz Textbook of Clinical Chemistry and Molecular Diagnostics. Edited by N Rifai, AR Horvath, CT Wittwer. Sixth edition. St. Louis, MO. Elsevier, 2018. pp 639-718