Pathology/Lab Coding Alert

Question: What is an MTHFR test for a pregnant patient, and what codes should I report for it?

Kentucky Subscriber

Answer: MTHFR (Methylene-tetra-hydro-folate-reductase) is an enzyme that is needed to metabolize homocysteine, an amino acid found in protein foods.

Why it’s important: When an expectant mother carries a genetic mutation (MTHFR) that inhibits the production of this enzyme, it can affect either her or the fetus. When homocysteine levels are elevated (because MTHFR is lacking), the risk of fetal neural tube defects and miscarriage increases. An elevated homocysteine level can also indicate an increased risk factor for blood clots, arteriosclerosis and strokes in the mother.

The code for the molecular pathology test for MTHFR is 81291 (MTHFR [5,10-methylenetetrahydrofolate reductase] [e.g., hereditary hypercoagulability] gene analysis, common variants [e.g., 677T, 1298C]).

The ordering physician should assign the diagnosis codes. Because she is pregnant, you might see a code such as 648.93 (Other current maternal conditions classifiable elsewhere, antepartum) as the primary diagnosis, or if she was showing signs of hypercoagulation problems, you might see 649.33 (Coagulation defects complicating pregnancy, childbirth, or the puerperium, antepartum condition or complication). If the test identifies an MTHFR genetic mutation, the proper code is 270.4 (Disturbances of sulphur-bearing amino-acid metabolism).

ICD-10: When ICD-9 becomes ICD-10 in Oct. 2014, you’ll report the following equivalents:

648.93 = O99.89 (Other specified diseases and conditions complicating pregnancy, childbirth and the puerperium)

649.33 = O99.11X (Other diseases of the blood and blood-forming organs and certain disorders involving the immune mechanism complicating pregnancy) with a sixth digit of 1, 2 or 3 to indicate the trimester

270.4 = E72.12 (Methylenetetrahydrofolatereductase deficiency).