Castle's Test (with Vitamin B₁₂ and Normal Gastric Juice) in the Ileum in Patients with Genuine and Patients with Tapeworm Pernicious Anaemia

Abstract

A mixture of vitamin B,, and normal gastric juice, instilled through an intestinal tube into the ileum, produces haematological remission in patients with tapeworm pernicious anaemia. When a similar mixture is administered by mouth, this effect fails to occur. This observation constitutes evidence in favour of the view that Diphyllobothrium latum, attached to the proximal portion (jejunum) of the intestine, absorbs the vitamin B,, contained in the food, thus preventing vitamin bound to the intrinsic factor of the gastric juice from reaching the receptors in the distal portions of the small intestine of the host. In genuine pernicious anaemia, remission results from the administration of vitamin B,,+gastric juice both by mouth and into the ileum.

Causes of Vitamin B12 and Folate Deficiency

“…The fact that it causes vitamin B 12 deficiency was first recognized in 1886 when it was identified as the cause of "fish tapeworm anemia" [55], which mimics pernicious anemia. The tapeworm competes for vitamin B 12 with its human host, taking up large amounts of the vitamin from the intestinal lumen [56].…”

Parasites of the small intestine

“…Vitamin B 12 absorption takes place exclusively in the terminal ileum. In infected persons, therefore, the parasite gets exposed to the vitamin B 12 prior to the host being able to absorb it [37]. Why this does not occur with other parasites of the small bowel is unknown.…”