Assay of methylmalonic acid in the serum of patients with cobalamin deficiency using capillary gas chromatography-mass spectrometry.

Abstract

To determine the incidence of elevated levels of serum methylmalonic acid in patients with cobalamin deficiency, we utilized a new capillary gas chromatographic-mass spectrometric technique to measure methylmalonic acid in the serum of 73 patients with clinically confirmed cobalamin deficiency. Values ranged from 55 to 22,300 ng/ml, and 69 of the 73 patients had values above the normal range of 19-76 ng/ml as determined for 50 normal blood donors. In the cobalamin-deficient patients, serum methylmalonic acid was significantly correlated with the serum folate level and the degree of neurologic involvement. Some patients with pernicious anemia who were intermittently treated with cyanocobalamin were found to have elevated serum levels of methylmalonic acid while free of hematologic and neurologic abnormalities. A cobalamin-deficient patient is described with a normal serum cobalamin and an elevated serum methylmalonic acid. We conclude that the ability to measure methylmalonic acid in human serum will be useful in studies designed to determine the incidence of cobalamin deficiency in various patient populations. IntroductionPrevious investigators have shown that most patients with cobalamin (Cbl, vitamin B12)' deficiency have elevated levels of methylmalonic acid in their urine (1-12). The origin of the methylmalonic acid has recently been elucidated (13) and is illustrated in Fig. 1. In Cbl deficiency, reduced levels ofadenosylCbl result in decreased activity of L-methylmalonyl-coenzyme A (CoA) mutase and a resultant increase in intracellular levels ofL-methylmalonyl-CoA. D-methylmalonyl-CoA is also elevated due to the activity of D,L-methylmalonyl-CoA racemase (14) and is cleaved to coenzyme A and methylmalonic acid by the recently recognized and characterized enzyme, D-methylmalonyl-CoA hydrolase (13). Methylmalonic acid is then released into blood in unknown amounts and is excreted in the urine. In normal individuals (15) and laboratory animals (13), about

Relationship between methylmalonic acid, homocysteine, vitamin B12 intake and status and socio-economic indices, in a subset of participants in the British National Diet and Nutrition Survey of people aged 65 y and over

“…Table 3 of the present study indicate that some elderly respondents with raised MMA levels also have abnormal plasma urea and creatinine concentration, and therefore impaired kidney function. Many other studies have also detected a link between raised blood MMA levels and impaired kidney function (Stabler et al, 1986;Rasmussen et al, 1990a, b;Joosten et al, 1993;Lindenbaum et al, 1994;Koehler et al, 1996;Norman, 1998Norman, , 1999van Asselt et al, 1998;Herrmann et al, 2000;Hvas et al, 2000). According to Whitehead et al (1994), the 97.5th centile of plasma creatinine in adults aged 25 -55 y is approximately 122 mmol=l (males) and 100 mmol=l (females), and for plasma urea it is 7.6 mmol=l (males) and 6.8 mmol=l (females).…”

“…Following the early studies that demonstrated the basic relationship between vitamin B 12 and MMA in man (Gompertz et al, 1967;Chanarin et al, 1973;Norman et al, 1982;Carmel, 2000), and which established reliable assay techniques for MMA (Stabler et al, 1986), were a number of key studies showing a surprisingly high prevalence of raised MMA levels in the plasma of older people, where it appeared to provide a more reliable indicator of functional vitamin B 12 status than serum or plasma vitamin B 12 concentrations per se (Lindenbaum et al, 1988;Rasmussen et al, 1989;Moelby et al, 1990;Joosten et al, 1993;Allen & Casterline, 1994;Lindenbaum et al, 1994;Koehler et al, 1996;Baik & Russell, 1999;Bjorkegren & Svardsudd, 1999;Herrmann et al, 2000). Clearly, the ageing process in itself, and the increasing prevalence of age-related medical conditions that impair vitamin B 12 absorption, both increase the probability that people will become vitamin B 12 -deficient as they grow older.…”

Elevated serum levels of methylmalonic acid and homocysteine in elderly people. A population‐based intervention study

“…Cobalamin is a coenzyme in the conversion of methylmalonyl-CoA to succinyl-CoA [7,8]. In a situation with deficiency of cobalamin, methylmalonyl-CoA is converted to methylmalonic acid (MMA) rather than to succinyl-CoA [9].…”

Response of early weaned piglets to graded levels of dietary cobalamin

“…A deficiency of dietary cobalamin leads to depressed tissue and plasma cobalamin concentrations (Stangl et al 2000). Additionally, the prolonged consumption of cobalamin-deficient diets (Stangl et al 2000), administration of cobalamin analogues (Stabler et al 1997), or the inactivation of cobalamin via nitrous oxide exposure ) can lead to the development of hyperhomocysteinemia via inhibition of methionine synthase and methylmalonicaciduria (Stabler et al 1997) via inhibition of methylmalonyl-CoA mutase.…”