Co⁵⁷ Vitamin B₁₂ Clearance Studies in Pernicious Anaemia

Abstract

1) Clearance rate of intravenously administered radioactive vitamin B,, in untreated pernicious anaemia patients is slow in 50 per cent of cases studied.(2) Administration of labelled vitamin B,, bound to slow serum to 'normal clearing' pernicious anaemia subjects or to normal persons is followed by normal clearance rate.(3) Radioactive vitamin B,, bound to normal serum is cleared at a normal rate in pernicious anaemia patients with slow clearance rate. (4) Radioactive vitamin B,, bound to slow serum when mixed with normal serum in proportions of 1:l or 1 : O S 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 B,, bound to 'slow serum'.

Plasma Clearance Studies of 57Co Vitamin B12 in Fish Tapeworm Anaemia

“…These estimates fall well within the normal range and results are identical with those reported in patients with P.A. in relapse (Meyer et al 1967). In part (c) are shown plasma radioactivity in four patients with F.T.A., demonstrating that when a tracer dose of (0.066 pg.)…”

“…The possibility exists that there was insufficient 'clearance factor' in the unheated serum of donors used for patients KH and HT, and that increasing amount of normal serum would have produced a normal pattern or that 'clearance factor' in donor serum given to patient ND was not destroyed by heating at 56" C. for 30 minutes and so administration of "Co B12 normal serum produced the same effect seen in part (b) of Table I1 and which was previously described in patients with P.A. in relapse (Meyer et al 1967).…”

“…in relapse, administration of a tracer dose of radioactive BIZ pre-bound to normal serum will convert the slow clearance to a normal rate, suggesting the presence of a 'clearance factor' present in normal serum and either absent or reduced in F.T.A. (Meyer et al 1967). The above results also suggest that 'clearance factor' is heat labile, since following exposure of normal serum pre-bound with a tracer dose of labelled vitamin B12 to a temperature of 56" C. for 30 minutes, correction of slow clearance to normal does not take place.…”

“…serum pre-bound with 57C0 BI2 in vitro and administered to patients with P.A. in relapse, the slow rate is converted to normal (Meyer et al 1967). This ability to correct 'slow' serum was lost or reduced when normal serum was heated to 56" C. for 30 minutes prior to addition to 'slow' serum pre-bound with radioactive B12.…”

“…It has been shown in many laboratories that plasma clearance of an intravenously administered tracer dose of radioactive vitamin Blz is slower in patients with pernicious anaemia in relapse, malabsorption syndrome and fish tapeworm anaemia than in normal persons (Mollin et al 1956, Miller et al 1957, Brody et al 1960, Hall et al 1962. More recently it was demonstrated that in a group of 14 patients with untreated pernicious anaemia half the subjects had slow clearance rates while the remainder fell into the normal range (Meyer et al 1967). A patient with macrotytic anaemia and megaloblastic bone marrow 19 years following gastrectomy showed clearance also.…”