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General Information:

Web Links:

Mayo Clinic Laboratories

Test Code LAB0255265 Homocysteine, Total, Plasma

Additional Codes

Mayo Test ID
HCYSP

Performing Laboratory

Mayo Clinic Laboratories in Rochester

Useful For

An aid for screening patients suspected of having an inherited disorder of methionine metabolism including:

-Cystathionine beta-synthase deficiency (homocystinuria)

-Methylenetetrahydrofolate reductase deficiency and its thermolabile variants

-Methionine synthase deficiency

-Cobalamin (Cbl) metabolism

-Combined methyl-Cbl and adenosyl-Cbl deficiencies: Cbl C2, Cbl D2, and Cbl F3 deficiencies

-Methyl-Cbl specific deficiencies: Cbl D-Var1, Cbl E, and Cbl G deficiencies

-Transcobalamin II deficiency

-Adenosylhomocysteinase deficiency

-Glycine N-methyltransferase deficiency

-Methionine adenosyltransferase I/III deficiency

 

Screening and monitoring patients suspected of, or confirmed with, an inherited disorder of methionine metabolism using plasma specimens

 

Evaluating individuals with suspected deficiency of vitamin B12 or folate

Method Name

Liquid Chromatography Tandem Mass Spectrometry (LC-MS/MS)

Reporting Name

Homocysteine, Total, P

Specimen Type

Plasma EDTA


Necessary Information


1. Patient's age and sex are required.

2. Biochemical Genetics Patient Information (T602) is recommended, but not required, for suspected cases of inherited disorders of methionine metabolism.



Specimen Required


Supplies: Sarstedt Aliquot Tube, 5 mL (T914)

Collection Container/Tube:

Preferred: Lavender top (EDTA)

Acceptable: Green top (sodium or lithium heparin)

Submission Container/Tube: Plastic vial

Specimen Volume: 1 mL

Collection Instructions:

1. Immediately place specimen on wet ice.

2. Within 4 hours of collection, centrifuge and aliquot plasma into a plastic vial.

3. If blood cannot be placed on wet ice immediately, then within 1 hour of collection, centrifuge and aliquot plasma into a plastic vial.

4. A refrigerated centrifuge is not required if the above time restrictions are met.


Specimen Minimum Volume

0.3 mL

Specimen Stability Information

Specimen Type Temperature Time
Plasma EDTA Refrigerated (preferred) 28 days
  Frozen  309 days
  Ambient  28 days

Reject Due To

Gross hemolysis OK
Gross lipemia OK
Gross icterus OK

Reference Values

Age

Total homocysteine (nmol/mL)

Female

Male

0-11 months

3.1-8.3

3.2-9.7

12-23 months

3.2-8.3

3.3-9.6

24-35 months

3.2-8.2

3.3-9.6

3 years

3.2-8.2

3.3-9.6

4 years

3.3-8.2

3.4-9.5

5 years

3.4-8.1

3.5-9.4

6 years

3.5-8.1

3.6-9.4

7 years

3.5-8.1

3.7-9.4

8 years

3.6-8.2

3.8-9.3

9 years

3.7-8.2

3.9-9.4

10 years

3.8-8.3

4.1-9.4

11 years

3.9-8.4

4.3-9.4

12 years

3.9-8.6

4.4-9.5

13 years

4.0-8.7

4.6-9.6

14 years

4.1-8.8

4.8-9.7

15 years

4.2-8.9

5.0-9.8

16 years

4.2-9.1

5.2-9.9

17 years

4.3-9.2

5.4-10.0

18 years

4.3-9.3

5.6-10.1

19 years

4.4-9.5

5.7-10.3

20 years

4.4-9.6

5.9-10.5

21 years

4.4-9.8

6.0-10.6

22 years

4.4-9.9

6.1-10.8

23 years

4.4-10.1

6.2-11.0

24 years

4.4-10.3

6.2-11.1

25 years

4.4-10.4

6.3-11.3

26 years

4.4-10.6

6.3-11.4

27 years

4.3-10.8

6.4-11.6

28 years

4.3-11.0

6.4-11.7

29 years

4.3-11.2

6.4-11.8

30 years

4.3-11.4

6.4-11.9

31 years

4.4-11.6

6.4-12.1

32 years

4.4-11.8

6.4-12.2

33 years

4.4-11.9

6.4-12.3

34 years

4.5-12.1

6.4-12.4

35 years

4.5-12.2

6.4-12.6

36 years

4.6-12.4

6.4-12.8

37 years

4.6-12.5

6.4-12.9

38 years

4.7-12.7

6.4-13.1

39 years

4.7-12.8

6.4-13.2

40 years

4.8-13.0

6.5-13.4

41 years

4.8-13.2

6.5-13.5

42 years

4.8-13.4

6.5-13.7

43 years

4.9-13.5

6.6-13.9

44 years

4.9-13.7

6.6-14.0

45 years

4.9-13.9

6.6-14.2

46 years

4.9-14.0

6.7-14.4

47 years

4.9-14.2

6.7-14.5

48 years

5.0-14.3

6.8-14.7

49 years

5.0-14.4

6.8-14.9

50 years

5.0-14.5

6.8-15.0

51 years

5.1-14.6

6.8-15.2

52 years

5.1-14.7

6.9-15.4

53 years

5.1-14.8

6.9-15.5

54 years

5.2-14.9

6.9-15.6

55 years

5.2-15.0

6.9-15.7

56 years

5.3-15.0

6.9-15.8

57 years

5.3-15.1

6.9-15.9

58 years

5.3-15.2

6.9-16.0

59 years

5.4-15.2

6.9-16.0

60 years

5.4-15.3

6.9-16.1

61 years

5.4-15.4

7.0-16.2

62 years

5.5-15.4

7.0-16.2

63 years

5.5-15.5

7.0-16.3

64 years

5.6-15.5

7.1-16.3

65 years

5.6-15.6

7.1-16.3

66 years

5.7-15.6

7.1-16.3

67 years

5.7-15.7

7.2-16.3

68 years

5.8-15.7

7.2-16.3

69 years

5.9-15.7

7.2-16.3

70 years

6.0-15.8

7.3-16.3

71 years

6.1-15.8

7.3-16.3

72 years

6.2-15.8

7.3-16.3

73 years

6.3-15.9

7.3-16.3

74 years

6.4-15.9

7.3-16.3

75 years

6.5-15.9

7.3-16.3

76 years

6.6-15.9

7.3-16.3

77 years

6.7-16.0

7.4-16.3

78 years

6.8-16.0

7.4-16.3

79 years

6.9-16.0

7.5-16.3

80 years

7.0-16.0

7.5-16.3

81 years

7.1-16.0

7.7-16.2

82 years

7.2-16.0

7.8-16.2

83 years

7.2-16.0

7.9-16.2

84 years

7.3-16.0

8.0-16.2

85 years

7.3-16.0

8.2-16.2

>85 years

7.4-16.0

8.3-16.2

Interpretation

Elevated homocysteine concentrations are considered informative in patients evaluated for suspected nutritional deficiencies (vitamin B12, folate) and inborn errors of metabolism. Measurement of methylmalonic acid (MMA) distinguishes between vitamin B12 (cobalamin) and folate deficiencies, as MMA is only elevated in vitamin B12 deficiency. Treatment response can be evaluated by monitoring plasma homocysteine concentrations over time.

Day(s) Performed

Monday through Friday

Report Available

3 to 5 days

Specimen Retention Time

1 week

Test Classification

This test was developed and its performance characteristics determined by Mayo Clinic in a manner consistent with CLIA requirements. It has not been cleared or approved by the US Food and Drug Administration.

CPT Code Information

83090

LOINC Code Information

Test ID Test Order Name Order LOINC Value
HCYSP Homocysteine, Total, P 13965-9

 

Result ID Test Result Name Result LOINC Value
80379 Homocysteine, Total, P 13965-9