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HelpTest Code HCMM Homocysteine (Total), Methylmalonic Acid, and Methylcitric Acid, Blood Spot
Performing Laboratory
Mayo Clinic Laboratories in Rochester
Reporting Name
HCMM, BSSpecimen Type
Whole bloodOrdering Guidance
The preferred test for evaluating adults for an inherited disorder of methionine, cobalamin, or propionate metabolism is CMMPP / Cobalamin, Methionine, and Methylmalonic Acid Pathways, Plasma or CMMPS / Cobalamin, Methionine, and Methylmalonic Acid Pathways, Serum.
Specimen Required
Supplies: Card-Blood Spot Collection (Filter Paper) (T493)
Container/Tube:
Preferred: Card-Blood Spot Collection (Filter Paper)
Acceptable: Local newborn screening card, Whatman Protein Saver 903 filter paper, PerkinElmer 226 (formerly Ahlstrom 226) filter paper, Munktell filter paper
Specimen Volume: 2 Blood spots
Collection Instructions:
1. Do not use device or capillary tube containing EDTA or ACD to collect specimen. Sodium heparin is acceptable but must be spotted on card the same day as collected.
2. Completely fill at least 2 circles on the filter paper card (approximately 100 microliters blood per circle) using blood from a heel or finger stick.
3. Let blood dry on filter paper at ambient temperature in a horizontal position for a minimum of 3 hours.
4. Do not expose specimen to heat or direct sunlight.
5. Do not stack wet specimens.
6. Keep specimen dry.
Additional Information:
1. For collection instructions, see Blood Spot Collection Instructions
2. For collection instructions in Spanish, see Blood Spot Collection Card-Spanish Instructions (T777)
3. For collection instructions in Chinese, see Blood Spot Collection Card-Chinese Instructions (T800)
Reject Due To
| Shows serum rings; Insufficient specimen | Reject |
Specimen Stability Information
| Specimen Type | Temperature | Time | Special Container |
|---|---|---|---|
| Whole blood | Ambient (preferred) | FILTER PAPER | |
| Frozen | FILTER PAPER | ||
| Refrigerated | FILTER PAPER | ||
Specimen Minimum Volume
1 Blood spot
Special Instructions
Day(s) Performed
Monday, Thursday
Specimen Retention Time
1 yearReport Available
3 to 6 daysReference Values
HOMOCYSTEINE:
<9.0 nmol/mL
METHYLMALONIC ACID:
<4.0 nmol/mL
METHYLCITRIC ACID:
<1.0 nmol/mL
An interpretive report will also be provided.
Useful For
Second-tier assay of newborn screening specimens when abnormal propionyl carnitine or methionine concentrations are identified in a primary newborn screen
CPT Code Information
83090
83918
LOINC Code Information
| Test ID | Test Order Name | Order LOINC Value |
|---|---|---|
| HCMM | HCMM, BS | 100765-7 |
| Result ID | Test Result Name | Result LOINC Value |
|---|---|---|
| 50252 | Homocysteine | 54301-7 |
| 50253 | Methylmalonic Acid | 82385-6 |
| 50254 | Methylcitric Acid | 82386-4 |
| 50255 | Interpretation | 59462-2 |
| 50257 | Reviewed By | 18771-6 |
Disease States
- Homocystinuria
Forms
1. Biochemical Genetics Patient Information (T602)
2. If not ordering electronically, complete, print, and send a Biochemical Genetics Test Request (T798) with the specimen.
Supportive Data
In a Mayo study that analyzed specimens from 200 unaffected neonates, clear clinical discrimination was observed when compared to patients with defects of propionate or methionine metabolism. The 99.5 percentile, determined from the analysis of 200 dried blood spots of unaffected controls, for methylmalonic acid (MMA), methylcitric acid (MCA), and homocysteine (HCY), are 1.58 nmol/mL, 0.62 nmol/mL, and 9.9 nmol/mL, respectively, providing clear clinical discrimination from patients with defects of propionate or methionine metabolism (eg, methylmalonic acidemia: MMA=31.9 nmol/mL; propionic acidemia: MCA=12.8 nmol/mL; homocystinuria: HCY=189 nmol/mL).