Homocysteine, Total, Plasma (HCYSP)

Test Code: HCYSPSO

Overview
Ordering
Specimen
Performing
Clinical/Interpretive
Contacts
Coding

Synonyms/Keywords

Cystathionine beta-synthase deficiency
Methylenetetrahydrofolate reductase deficiency (MTHFR)
MTHFR deficiency
Methionine synthase deficiency
Cobalamin (Cbl) metabolism
Methyl-Cobalamin deficiency
Adenosyl-cobalamin deficiency
Cbl C2 deficiency
Cbl D2 deficiency
Cbl F3 deficiency
Cbl D-Var1 deficiency
Cbl E deficiency
Cbl G deficiency
Transcobalamin II deficiency
Adenosylhomocysteinase (AHCY) deficiency
Glycine N-methyltransferase (GNMT) deficiency
Methionine adenosyltransferase (MAT) I/III deficiency
Cobalamin C2 deficiencyCobalamin D2 deficiency
Cobalamin F3 deficiency
Cobalamin D-Variant 1 deficiency
Cobalamin E deficiency
Cobalamin G deficiency

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 (MTHFR) 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 (AHCY) deficiency
-Glycine N-methyltransferase (GNMT) deficiency
-Methionine adenosyltransferase (MAT) I/III deficiency
-Screening and monitoring patients suspected of or confirmed with an inherited disorder of methionine metabolism
-Evaluating individuals with suspected deficiency of vitamin B12 or folate.

Specimen Requirements

Fasting Required	Specimen Type	Preferred Container/Tube	Acceptable Container/Tube	Specimen Volume	Specimen Minimum Volume (allows for 1 repeat)	Pediatric Minimum Volume (no repeat)
No	EDTA Plasma	Lavender Top Tube (LTT)	Green Top Tube (sodium or lithium heparin)	1.0 mL		0.10 mL

Collection Processing Instructions

Centrifuge and separate plasma from cells within 4 hours of collection.

Fill out the following form: Biochemical Genetics Patient Information

Specimen Stability Information

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

Interference

Factors that may influence and increase plasma homocysteine include:

-Age

-Smoking

-Poor diet/cofactor deficiencies

-Chronic kidney disease/renal disease

-Hypothyroidism

Medications that may increase homocysteine concentrations include:

Medication	Effect
Methotrexate	5-Methyltetrahydrofolate depletion
Azuridine	Vitamin B6 antagonist
Nitrous Oxide	Inactivation of methionine synthase
Phenytoin	Interference with folate metabolism
Carbamazepine	Interference with folate metabolism
Oral Contraceptives	Estrogen-induced vitamin B6 deficiency

Performing Laboratory Information

Performing Location	Day(s) Test Performed	Analytical Time	Methodology/Instrumentation
Mayo Clinical Laboratories	Monday through Friday	3 days	Liquid Chromatography-Tandem Mass Spectrometry (LC-MS/MS)

Reference Lab

Mayo Clinic Laboratories

Reference Range Information

Performing Location	Reference Range
Mayo Clinical Laboratories	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

Performing Location

Reference Range

Mayo Clinical Laboratories

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 infomative in patients evaluated for suspected nutritional deficiencies (vitamin B12, foltate) and inborn errors of metabolism. Measurement of methylmalonic acid (MMA) distinguishes between 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.

Outreach CPTs

CPT	Modifier (if needed)	Quantity	Description	Comments
83090		1	Homocysteine, Total, Plasma

Synonyms/Keywords

Ordering Applications

Ordering Application	Description
Clinical Order Manager	Homocysteine, Total, Plasma (HCYSP)
Cerner	Homocysteine, Total, Plasma (HCYSP)

If the ordering application you are looking for is not listed, contact your local laboratory for assistance.