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Test Code HCYSP Homocysteine, Total, Plasma

Performing Laboratory

Mayo Clinic Laboratories in Rochester

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

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

Day(s) Performed

Monday through Friday

CPT Code Information

83090

Clinical Information

Homocysteine is an intermediary in the sulfur-amino acid metabolism pathways, linking the methionine cycle to the folate cycle. Inborn errors of metabolism that lead to homocysteinemia or homocystinuria include cystathionine beta-synthase deficiency (homocystinuria) and various defects of methionine remethylation. Genetic defects in vitamin cofactors (vitamins B6, B12, and folate) and nutritional deficiency of vitamin B12 and folate also lead to abnormal homocysteine accumulation.

 

Homocysteine concentration is an indicator of acquired folate or cobalamin deficiency and is a contributing factor in the pathogenesis of neural tube defects. Homocysteine was once thought to be an independent predictor of cardiovascular disease (atherosclerosis, heart disease, thromboembolism), as early observational studies prior to the year 2000 linked homocysteine to cardiovascular risk and morbidity and mortality. However, following US Food and Drug Administration mandated folic acid supplementation in 1998, homocysteine concentrations decreased by approximately 10% without a similar change in cardiovascular or ischemic events. Currently, the use of homocysteine for assessment of cardiovascular risk is uncertain and controversial. Based on several meta-analyses, at present, homocysteine may be regarded as a weak risk factor for coronary heart disease, and there is a lack of direct causal relationship between hyperhomocysteinemia and cardiovascular disease. It is most likely an indicator of poor lifestyle and diet.

 

This test should be used in conjunction with plasma amino acids, quantitative acylcarnitines, methylmalonic acid, and urine organic acids to aid in the biochemical screening for primary and secondary disorders of methionine metabolism.

Report Available

3 to 5 days

Reject Due To

Gross hemolysis OK
Gross lipemia OK
Gross icterus OK

Method Name

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