The Lab Panel
Tests To Ask For — And Why Each One Matters
Standard blood panels don't include MTHFR testing. You have to ask for it specifically. Here is the complete panel that gives you the full picture — what's genetic, what's functional, and what's downstream.
| Test | What It Measures | Why It Matters | What To Look For |
|---|---|---|---|
| MTHFR C677T & A1298C | Genetic variants in the MTHFR gene | Confirms whether enzyme function is reduced and by how much | Heterozygous (one copy) or homozygous (two copies) |
| Homocysteine | Amino acid that accumulates when methylation is impaired | Functional marker — confirms methylation isn't working even if genetics aren't tested | Optimal: under 9 μmol/L. Concern: above 12. High risk: above 15. |
| Serum Folate + RBC Folate | Folate in blood plasma and within red blood cells | Serum can look normal while RBC is low — RBC is more accurate for tissue stores | RBC folate >400 ng/mL is optimal |
| Methylmalonic Acid (MMA) | B12 activity at the cellular level | Serum B12 can look normal while MMA is elevated, indicating functional B12 deficiency | Should be <0.40 μmol/L |
| Ferritin + Full Iron Panel | Iron storage and transport | Ferritin is the most sensitive marker of iron depletion — often low before standard iron tests show any problem | Optimal ferritin: 50–100 ng/mL for women |
| Vitamin D (25-OH) | Active vitamin D status | Low D is common with MTHFR; it overlaps heavily with fatigue and mood symptoms | Optimal: 50–80 ng/mL |
| Thyroid Panel (TSH, Free T3, Free T4) | Full thyroid function | MTHFR affects T4→T3 conversion in the liver; hypothyroid symptoms often overlap. TSH alone is insufficient. | Request Free T3 and Free T4 specifically, not just TSH |
| CBC with differential | Red blood cell size, shape, count | Megaloblastic anemia (large, immature RBCs) is a sign of functional folate/B12 deficiency | Elevated MCV (mean corpuscular volume) with low hemoglobin |
Lab Panel Request Card
Print this and bring it to your appointment. Hand it to your doctor or nurse.
Test 1
MTHFR C677T and A1298C genetic panel
Test 2
Homocysteine (plasma)
Test 3
RBC Folate (not just serum folate)
Test 4
Methylmalonic Acid (MMA)
Test 5
Ferritin + Full Iron Panel (TIBC, serum iron)
Test 6
25-OH Vitamin D
Test 7
Thyroid: TSH, Free T3, Free T4
Test 8
CBC with differential
I am researching a possible MTHFR variant and its downstream effects. I would like to rule in or out methylation impairment as a contributing factor to my symptoms. I understand these are not emergency tests but would appreciate including them in my next workup.
The Conversation
How To Raise This Without Sounding Like You've "Gone Online"
The biggest challenge is framing. If you walk in saying "I think I have MTHFR and it's causing my autism and OCD," most physicians will disengage immediately — not because they're wrong, but because the framing sounds self-diagnosed and conclusory.
Lead with your symptoms. Ask about the mechanism. Request the tests. Let the results do the persuading.
Opening Scripts That Work
For Yourself (Fatigue / Brain Fog / Iron)
"I've been experiencing [symptoms] for [timeframe]. My standard labs have come back mostly normal, but the symptoms aren't resolving. I'd like to investigate whether there's a methylation component — specifically, I'd like to test homocysteine, RBC folate, MMA, and if possible the MTHFR genetic panel. Can we add those to my next workup?"
For Your Child (ASD / ADHD / Language Delay)
"I've been reading about the connection between folate receptor function and neurodevelopmental outcomes. There are published clinical trials on leucovorin in children with autism and folate receptor antibodies that show meaningful improvements. I'd like to explore whether my child might benefit from folate receptor antibody testing and possibly a trial of active methylfolate supplementation. Can you refer me to a developmental pediatrician or functional neurologist who is familiar with this research?"
If You Already Have Results and Want Next Steps
"My MTHFR came back [result] and my homocysteine is [value]. I understand the standard position is that MTHFR alone isn't clinically significant, but given my symptom history and the homocysteine elevation, I'd like to discuss a trial of L-5-methylfolate supplementation and re-test homocysteine in 90 days to see if it normalizes. Is that something you'd be willing to manage with me?"
If your doctor dismisses you: You are not wrong for asking. MTHFR testing is not fringe medicine — it is ordered by cardiologists, hematologists, and OB/GYNs routinely. The hesitation usually comes from primary care physicians who haven't seen enough cases to connect the pattern. Ask for a referral to an integrative medicine physician or functional medicine doctor.
Who To See
The Right Specialists For This Work
Functional Medicine Physician
Most likely to understand the full methylation picture and work with you on supplementation protocols.
Find one: ifm.org/find-a-practitioner
Integrative Neurologist
For ASD and neurodevelopmental cases specifically. Familiar with leucovorin/folate protocols in children.
Search: "integrative neurology MTHFR"
Developmental Pediatrician
For children with ASD/ADHD diagnoses. Can order folate receptor antibody testing and monitor supplementation.
Ask for referral from your pediatrician
Naturopathic Doctor (ND)
Often the most willing to engage with methylation protocols and supplementation without resistance.
Find one: naturopathic.org