Thiamine overdose is a rare condition that occurs when excessive amounts of vitamin B1 accumulate in the body, typically from high-dose supplementation. It is caused by consuming too much thiamine through supplements, as dietary sources alone rarely cause toxicity. The Vitamin B1 (Thiamine) LC/MS/MS test is the most important test for diagnosis, as it precisely measures elevated thiamine levels in the blood.
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Thiamine overdose is caused by consuming excessive amounts of vitamin B1, almost always through high-dose supplements rather than food sources. While thiamine is water-soluble and excess amounts are typically excreted through urine, very high supplemental doses can temporarily overwhelm the body's elimination capacity. This leads to elevated blood levels that can cause symptoms like restlessness, fluid retention, nausea, rapid pulse, irregular heartbeat, low blood pressure, and hives. Dietary sources of thiamine, such as whole grains, legumes, and pork, do not typically cause overdose.
The Vitamin B1 (Thiamine) LC/MS/MS test is the most important test for thiamine overdose because it uses liquid chromatography-tandem mass spectrometry technology to precisely measure thiamine levels in your blood. This advanced testing method can detect even slightly elevated concentrations that may be causing overdose symptoms such as restlessness, fluid retention, nausea, weakness, rapid pulse, irregular heartbeat, low blood pressure, and hives. The high accuracy of this test allows healthcare providers to definitively confirm whether your symptoms are related to excess vitamin B1, enabling them to make informed decisions about discontinuing or adjusting your supplement regimen.
You should get tested if you are taking high-dose thiamine supplements and experience symptoms like restlessness, unexplained swelling or fluid retention, persistent nausea, weakness, rapid or irregular heartbeat, low blood pressure, or hives. Testing is especially important if you recently started a new supplement regimen or increased your thiamine dosage and noticed these symptoms shortly afterward. Getting tested promptly helps confirm whether elevated vitamin B1 levels are the cause of your symptoms so your healthcare provider can adjust your supplement intake appropriately.
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What this means
Your Vitamin B1 levels are slightly below the optimal range, which may explain feelings of fatigue, low energy, or irritability you've been experiencing. While this is not an emergency, low thiamine can affect how efficiently your body converts food into energy and supports nerve function.
Recommended actions
Include more whole grains, legumes, nuts, and lean pork in your diet
Consider a B-complex supplement after consulting with your healthcare provider
Reduce or eliminate alcohol consumption, as it depletes B1 stores
Retest in 8-12 weeks after making dietary changes to monitor improvement
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