Thiamine deficiency

Thiamine deficiency is caused by a low level of thiamine (vitamin B₁) in the body, and when severe, a deficiency may manifest in adults as beriberi.

There are two main forms:

• wet beriberi: high-output cardiac failure predominates

  • Shoshin beriberi ³: severe acute wet form with high mortality

• dry beriberi: neurological dysfunction predominates

  • ​Wernicke encephalopathy: specific subtype of dry beriberi

In practice patients may present with mixed beriberi, i.e. with elements of both the wet and dry forms.

Clinical presentation

Wet beriberi

• high output heart failure

  • symptoms may include dyspnea, palpitations, fatigue

  • exam may reveal signs of elevated filling pressures including jugular venous distention and/or pulmonary vascular congestion

  • periphery may be warm with vigorous palpable arterial pulses

    • secondary to a low systemic vascular resistance with vasodilation

• features of dry beriberi are often also present

Dry beriberi

• altered mentation

  • ranging from subtle memory impairment to profound encephalopathy

• ataxia

  • vestibulo-cerebellar dysfunction predominantly affecting the lower extremities and gait

• visual disturbance

  • particularly oculomotor abnormalities e.g. nystagmus, ophthalmoplegia

• sensory and/or motor deficits

  • axonal degeneration with resultant myopathy and neuropathy

  • areflexia may also be noted

Tachycardia is common with early in the disease course, and assessment of a core temperature may demonstrate hypothermia. Tachypnea may also be present with a respiratory alkalosis on a blood gas. An elevated serum lactate may be present.

Confirmatory testing may include a whole blood thiamine level or an erythrocyte transketolase activity; the latter may be reassessed after thiamine repletion.

Pathology

Etiology

Deficiency is typically related to insufficient thiamine intake, decreased gastrointestinal absorption, or increased elimination. Congenital causes are also a consideration, albeit with a far lower incidence.

• restricted ("fad") diets

• eating disorders

  • anorexia nervosa

  • bulimia nervosa

• excessive ethanol consumption

• chronic illness

• prolonged or poorly constructed total parenteral nutrition (TPN)

• gastrointestinal malabsorptive disorders

  • Crohn disease

  • celiac disease

  • infective enteritis

• AIDS

• malignancy

• renal replacement therapy

• post-starvation refeeding syndrome

• prior bariatric surgery e.g. gastric banding ¹

Radiographic features

The imaging features of beriberi reflect its underlying manifestations, and therefore in wet beriberi, cardiomegaly, pulmonary edema, dilated cardiomyopathy may be seen; however there are no pathognomonic cardiac imaging findings ⁵.

For example:

• in wet beriberi, bedside point of care ultrasonography may demonstrate:

  • dilation of the inferior vena cava with diminished respiratory variation

  • bilateral, symmetric lung rockets (>3 B lines per sonographic field) in a gravitationally dependent distribution

  • an elevated left ventricular outflow tract velocity time integral (VTI) consistent with a high stroke distance (and by extension cardiac output)

• in dry beriberi, the classic MRI features of Wernicke encephalopathy may be seen

In general, radiology is a corroborative tool in beriberi. The diagnosis is usually clinical with response to supplemental thiamine confirmatory.

Treatment and prognosis

Optimal treatment of beriberi relies upon a two-pronged approach:

• thiamine supplementation

  • commonly administered parenterally, often with magnesium

  • biotin may be administered for certain genetic causes e.g. loss of low-affinity thiamine uptake transporter function

• supportive therapies e.g. cardiac support

Recovery is often rapid once thiamine supplements are started. 

History and etymology

Beriberi derives from the Sinhalese for "weak, weak", a deliberate duplication of the same word to emphasize how poorly a patient with the condition feels ².

An unrecognised nutrient on the surface of rice which was eliminated during the polishing process was speculated to be the nutritional factor deficient in beriberi in 1901 by Gerrit Grijns (1865-1944). The structure of thiamine was defined by Robert R Williams (1886-1965) and colleagues in 1934, and in 1936 was demonstrated in an avian model to reverse the metabolic derangement in aerobic glucose utilization present in thiamine deficiency.