Urine gas chromatography-mass spectrometry revealed a highly elevated ratio of methylmalonic acid
(199.3; normal range: <1.0) and methyl citrate (33.6; normal range: <1.0; [Figure 1]a).
The following information was obtained from the case files: demographic data; background; family history; serum vitamin B12, folate, plasma homocysteine, and urine methylmalonic acid
(MMA) levels; and direct, indirect, and total bilirubin levels.
Secondary outcomes included NTB scores, serum methylmalonic acid
(MMA) and homocysteine.
According to the US National Institutes of Health, additional laboratory tests which include homocysteine and methylmalonic acid
values may also be needed to reliably detect low levels of vitamin B-12.
Compared with placebo, metformin significantly increased the mean serum concentration of methylmalonic acid
. The increase in methylmalonic acid
levels was associated with a significant increase in the severity of polyneuropathy.
Methylmalonic acidurias (MMAurias) are a heterogeneous group of inherited metabolic disorders (IMDs) leading to increased urinary methylmalonic acid
excretion.1 The aetiology of MMAurias includes isolated and combined with hyperhomocystenaemia.2Isolated MMAuria is caused by complete or partial deficiency of the enzyme methylmalonyl-CoA mutase (MCM) usually with normal serum methionine concentration.3,4 In intracellular Cobalamin-related remethylation disorders (Cb1-RD), MMAuria and hyperhomocystenaemia are present.
Age-related hearing loss, methylmalonic acid
, and vitamin B12 status in older adults.
Both actual cobalamin levels and levels of methylmalonic acid
(MMA) were evaluated in the study cats.
Further workup reveals a cobalamin (vitamin B,2) level of 82 pg/mL (reference range, 180 to 900 pg/mL) and a methylmalonic acid
level of >5 (reference range, <0.3).
Second, our study was based on serum B12 results, which alone, without other biochemical markers such as homocysteine, methylmalonic acid
might not be accurate measures of B12 deficiency.
Serum concentrations of Hcy and methylmalonic acid
(MMA) are elevated in VitB12 deficiency, due to a decreased rate of metabolism.
Laboratory findings were as follows: plasma methylmalonic acid
(MMA)  was highly increased: 17.4 [micro]mol/L (reference interval: 0-0.29 [micro]mol/L); total homocysteine was highly increased: 125 [micro]mol/L (reference interval: <12.5 [micro]mol/L); vitamin [B.sub.12] was low: 188 pg/mL (200-1100 pg/mL); and liver enzymes were slightly increased: alanine transaminase (ALT): 54 U/L (reference interval: 3-35 U/L); aspartate transaminase (AST): 48 U/L (reference interval: 15-46 U/L).