Co57 Vitamin B12 Clearance Studies in Pernicious Anaemia

• 1 Clearance rate of intravenously administered radioactive vitamin B₁₂ in untreated pernicious anaemia patients is slow in 50 per cent of cases studied.
• 2 Administration of labelled vitamin B₁₂ bound to slow serum to ‘normal clearing’ pernicious anaemia subjects or to normal persons is followed by normal clearance rate.
• 3 Radioactive vitamin B₁₂ bound to normal serum is cleared at a normal rate in pernicious anaemia patients with slow clearance rate.
• 4 Radioactive vitamin B₁₂ bound to slow serum when mixed with normal serum in proportions of 1:1 or 1:0.5 is cleared at a normal rate in ‘slow clearing’ pernicious anaemia patients.
• 5 These studies suggest the presence of a ‘serum factor’ in normal serum and some patients with pernicious anaemia in relapse which enhances clearance of vitamin B₁₂ bound to ‘slow serum’.