Clinical spectrum and diagnosis of cobalamin deficiency [see comments]

To better estimate how frequently patients with low serum cobalamin levels in current clinical practice are truly deficient in Cbl and to determine the incidence of atypical or nonclassic presentations of Cbl deficiency, we prospectively studied 300 unselected consecutive patients with serum Cbl concentrations less than 200 pg/mL seen at two medical centers over a 2-year period

SP Stabler; RH Allen; DG Savage; J Lindenbaum


Scholarcy highlights

  • Serum levels of methylmalonic acid and/or total homocysteine were elevated greater than 3 SDs above the mean for normal subjects in 94% of the Cbl-responsive patients
  • 5 of the 59 patients who did not respond to Cbl had marked elevations of both serum methylmalonic acid and serum total homocysteine
  • With respect to the results of many of the tests listed in Tables 2 and 3, the patients with unknown Cbl status resembled those who did not respond to Cbl more than those who did
  • Our studies show that assays for serum methylmalonic acid and total homocysteine are useful in this regard, especially when both assays are performed
  • W e presently are studying the utility of performing assays for serum methylmalonic acid, total homocysteine, and anti-intrinsic factor antibodies on all patients with serum Cbl levels less than 300 pg/mL, and in rare patients with values greater than 300 pg/mL where the clinical picture is extremely suggestive of Cbl deficiency

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