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methylmalonate in 24 hr urine
Metabolism of methylmalonate is dependent upon vitamin B12.
Normal range:
- 24 hour urine: < 9.0 mg/day (< 76 umol/day)
- random urine: < 3.76 mg/g creatinine (< 3.6 mmol/mol creatinine)
Increases:
1) vitamin B12 deficiency (but NOT folate deficiency)
2) renal insufficiency (even mild renal insufficiency)
3) chemical interferences with color method
a) acetoacetate
b) ascorbate
c) creatinine
d) uric acid
4) congenital methylmalonic aciduria
Methods:
- GLC, GC-MS (random urine), color
Specimen:
1) 24 hour urine
- administer 10 g of L-valine orally.
- begin collection of urine immediately after L-valine administration
- add 10 mL of 6M HCl
- stable for 3 months when frozen
2) random urine:
- collect 2nd voided specimen after overnight fast
- store frozen.
Related
methylmalonate in serum
methylmalonate; methylmalonic acid (MMA)
General
24 hour urine
methylmalonate in urine
References
- Medical Knowledge Self Assessment Program (MKSAP) 11, American
College of Physicians, Philadelphia 1998
- Clinical Guide to Laboratory Tests, 3rd edition, NW Tietz
ed, WB Saunders, Philadelphia, 1995