bubble_chart Overview

Vitamin B1 (abbreviated as B1), also known as thiamine, is water-soluble, acid-resistant but not alkali-resistant. It is abundant in grains, nuts, animal offal, eggs, and yeast. Over-processing of grains can lead to B1 loss. Raw fish and shellfish contain enzymes that destroy B1, and long-term consumption can easily lead to B1 deficiency.

B1 plays an important role in sugar metabolism in the body and can also inhibit the activity of cholinesterase. When B1 is deficient, sugar metabolism is inhibited, energy production is insufficient, and pyruvate and lactate accumulate in tissues, which can cause structural and functional changes in the nervous, cardiac, and brain tissues. At the same time, increased cholinesterase activity accelerates the hydrolysis of acetylcholine, which can interfere with nerve conduction and cause digestive symptoms such as slowed gastrointestinal motility and reduced digestive juice secretion.

The recommended daily dietary intake of B1 is 0.4mg for infants and 0.6–1.8mg for children and adolescents.

bubble_chart Diagnosis

[Auxiliary Examination]

Urinary thiamine excretion <15µg/24h(正常值為40～100µg/24h)，一次尿樣本中的硫胺素/肌酐比率<120µg/g肌酐(正常值為176µg/g肌酐)，紅細胞轉酮醇酶活性在加入b1後較加入前增高> 20%, significantly increased levels of blood lactate and pyruvate (normal lactate value <18µg/dl，丙酮酸為0.7～1.2mg/dl) ，均可協助診斷。

(1) Medical history Infants breastfed by mothers with vitamin B1 deficiency; history of long-term consumption of refined rice and flour; history of cooking rice with alkali or discarding rice water; history of chronic liver or intestinal diseases leading to reduced B1 absorption; prolonged fever or surgical procedures increasing demand; history of long-term consumption of raw fish or shellfish; history of residing in areas where beriberi is endemic, etc.

(2) Clinical manifestations Infantile beriberi often presents acutely, while older children typically exhibit chronic onset. The main manifestations include the following three aspects:

1. Gastrointestinal symptoms: More common in infants, such as decreased appetite, diarrhea, vomiting, abdominal distension and fullness, constipation, and hepatomegaly.
2. Neurological symptoms: Infants may exhibit nerve paralysis and central nervous system symptoms, such as hoarseness, weak crying, ptosis, head and neck arching backward, inability to grasp, weak sucking, weakened or absent tendon reflexes, drowsiness, unconsciousness, and death from spasms. Older children primarily present with multiple peripheral neuropathies, initially showing symmetrical sensory abnormalities like swelling, numbness, tingling pain, and burning sensations, as well as tenderness in the gastrocnemius muscle, followed by progressive motor paralysis ascending from the lower limbs, such as foot drop, wrist drop, frequent falls, difficulty squatting, and weakened or absent tendon reflexes.
3. Cardiovascular symptoms: Infants often display dysphoria, shortness of breath, pale complexion, perioral cyanosis, cough, and purplish skin mottling. Young infants may rapidly die from acute heart failure (fulminant cardiac beriberi) triggered by minor infections. Older children may experience palpitations and rapid breathing, with only a few developing heart failure. Edema may occur due to heart failure and hypoalbuminemia.

bubble_chart Treatment Measures

B1 Treatment: For mild cases, take 5-10 mg orally daily, and reduce to 1-5 mg for maintenance after symptoms disappear. For severe cases, administer 10 mg intramuscularly or intravenously twice daily. In cases of fulminant heart failure, administer 50-100 mg intravenously every 3 hours until heart failure is controlled, then reduce to 2-3 times daily while continuing heart failure treatment. Note that during improvement, sudden congestive heart failure leading to death may occasionally occur, possibly due to insufficient dosage or severe myocardial degeneration. In addition to B1 treatment, all other B vitamins should be supplemented. For breastfed infants with this condition, both mother and child require B1 treatment.

B1 toxicity has not been reported in humans. Patients with beriberi tolerate 500 mg of intravenous B1 well. However, in rare cases, doses of 100 mg or less may cause allergic reactions (thiamine shock), the nature of which remains unclear.

bubble_chart Differentiation

Beriberi should be differentiated from chronic arsenic poisoning, nervous system infections, porphyria, mononeuritis multiplex syndrome, Guillain-Barré syndrome, and various diseases that can cause congestive heart failure in children.