J. Metz et al., BIOCHEMICAL INDEXES OF VITAMIN-B-12 NUTRITION IN PREGNANT PATIENTS WITH SUBNORMAL SERUM VITAMIN-B-12 LEVELS, American journal of hematology, 48(4), 1995, pp. 251-255
To determine the significance of the commonly observed fall in serum v
itamin B-12 levels during pregnancy, serum levels of the B-12 metaboli
tes methylmalonic acid (MMA) and homocysteine (Hey) were measured in a
group of 50 pregnant patients with subnormal serum B-12 (range 45-199
pg/ml) and the results compared with those of 25 pregnant controls (s
erum B-12 208-580 pg/ml), Mean values for serum MMA and total Hey in t
he subnormal B-12 group were 445.4 nmol/L and 7.03 mu mol/L, respectiv
ely, which were not significantly different from the mean MMA of 440.5
nmol/L and Hey of 6.88 nmol/L in the controls, For the total group of
patients, neither serum MMA nor serum Hey levels correlated with seru
m B-12. One-third of pregnant patients showed elevated serum MMA value
s, independent of B-12 status, Significant elevation of serum Hey was
detected in only two patients, both with subnormal serum B-12 and hema
tological evidence of B-12 deficiency, We conclude that the usual fall
in serum B-12 concentration in pregnancy does not reflect B-12 defici
ency at the biochemical level, In establishing true B-12 deficiency in
pregnancy, the serum Hey level (in the absence of folate deficiency)
but not serum MMA, is of value. (C) 1995 Wiley-Liss, Inc.