Table 1.

Methylmalonic Acid Concentration in Phenotypes and Enzymatic Subtypes of Methylmalonic Acidemia

Methylmalonic Acidemia
Phenotype / Enzymatic
Subtype 1		Methylmalonic Acid Concentration
UrineBlood
Infantile/non-B12-responsive 2 /
mut0, mut–, cblB		1,000-10,000 mmol/mol Cr
  • 100-1,000 µmol/L (if eGFR >50 mL/min/1.73 m2)
  • 1,000-10,000 µmol/L in those w/advanced renal disease
B12-responsive 2 /
cblA, cblD-MMA, cblB, mut– (rare)		Tens - hundreds mmol/mol Cr5-100 µmol/L
MCEE deficiency 3100-6,800 mmol/mol Cr5-180 µmol/L
Normal 4<4 mmol/mol Cr<0.27 µmol/L

Cr = creatinine; eGFR = estimated glomerular filtration rate; MCEE = methylmalonyl-coenzyme A epimerase

1.

Biochemical parameters and clinical phenotype are not always concordant, partly because renal function can influence plasma MMA concentration [Kruszka et al 2013, Manoli et al 2013]. Patients in kidney failure show massive elevations in plasma MMA that can exceed 5,000 µmol/L.

2.

Approximate numbers, representing the author's experience with >150 individuals with the B12-responsive and non-B12-responsive types as well as data from Fowler et al [2008]

3.
4.

Normal values have not been exclusively derived from children or neonates. Some laboratories report urine MMA concentrations in mg/g/Cr (normal: <3 mg/g/Cr) and serum concentrations in nmol/L (normal: <271 nmol/L). The molecular weight of MMA is 118 g/mol.

From: Isolated Methylmalonic Acidemia

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