MMA Vitamin B12 Deficiency Methylmalonic Acid in Urine
This examination consists of the following tests:
- creatinine in urine
- methylmalonic acid in urine
Methylmalonic Acid in Urine follow-up test vitamin B12 deficiency
The test for methylmalonic acid has a place alongside the other tests performed to diagnose vitamin B12 deficiency. MMA and creatinine are measured.
Methylmalonic acid accumulates in the human body in vitamin B12 deficiency due to impaired conversion of methylmalonyl. Methylmalonic acid can be considered a functional direct marker of vitamin B12 deficiency. Indeed, methylmalonic acid provides a picture of biochemical damage at the cellular level.
Determination of Methylmalonic Acid
The determination of methylmalonic acid is useful because methylmalonic acid in urine is already elevated at the first subtle neurological changes that occur due to vitamin B12 deficiency at the cellular level. According to some studies, determination of MMA allows early recognition of the diagnosis before measurable changes in vitamin B12 concentration in blood occur or the first hematological abnormalities are detectable (2,3). Early diagnosis of vitamin B12 deficiency is essential since simple administration of this vitamin can prevent irreversible neurological damage. The MMA concentration normalizes after successful vitamin B12 therapy.
Increased MMA concentrations are also specific to vitamin B12 deficiency and are not seen in folate deficiency. One should keep in mind, however, the existence of congenital (hereditary) methylmalonic acid acidemia. Those with this trait always have elevated MMA concentrations. Falsely elevated values and due to hypovolemia (too low circulating blood volume) or insufficient renal function are avoided by determining methylmalonic acid in urine. Here the MMA concentration should be related to the excretion of creatinine (which is more or less constant daily) to correct for dilution effects of the urine.
So this test also measures the creatinine level.
When to measure?
The determination of MMA in urine is important in every patient with a relatively low and vitamin B12 value. Also in patients with anemia without clear cause and unexplained neurological abnormalities, this analysis can be useful.
You will receive a vacuum pump to suck up a tube of urine. Submitting a portion of the first morning urine (sober) facilitates the interpretation of the result because certain amino acids present in the diet. The concentrations of these interfering amino acids are lowest in the first morning urine.
Collecting spontaneous urine: Start with urinating, but let the first bit run off into the toilet. Then start collecting the urine in a jar. Stop collecting urine before you finish peeing and continue peeing in the toilet.
The urine sample is best stored in the refrigerator until shipment, before layover time you can mail the sample. No preservatives or other additives are required.
It is advisable to avoid histamine-rich foods before taking the urine.