Reference values for CFNL, CFND and LDIFlare?

Posted by crankycoder @crankycoder, 4 days ago

Hi all,

I'm looking to see if I can find reference ranges to detect SFN for corneal nerve fiber length (CNFL) and corneal nerve fiber density (CNFD).

The most recent numbers I could find are from doi: 10.2337/dc14-2311

Specifically for female age 50, I see in Table 3:

"Corneal Nerve Parameter Cutoff points for clinical use:"

CNFD 13.91 no./mm^2
CNFL 12.48 mm/mm^2

I'm also looking for reference ranges for LDIFlare - I see a paper from 2013: doi: 10.1371/journal.pone.0069920

Here - the cut off value is < 3.66cm^2 to detect SFN.

I'm asking because the labwork I got back came in with:

CNFL: 4.02 mm/mm^2
CNFD: 7.29 no/mm^2
LDIFlare: 3.14 cm^2

These all seem to be below the floor thresholds I can find. The hospital here in Toronto seems to claim these are 'normal' - am I completely out to lunch?

Interested in more discussions like this? Go to the Neuropathy Support Group.

Colleen Young, Connect Director | @colleenyoung | 1 day ago

Welcome, @crankycoder. I noticed you wished to insert links to research papers with your post. You will be able to add URLs to your posts in a few days. There is a brief period where new members can't post links. We do this to deter spammers and keep the community safe. Allow me to postthem for you.
- Normative values for corneal nerve morphology assessed using corneal confocal microscopy: a multinational normative data set https://pubmed.ncbi.nlm.nih.gov/25633665/
- The Rate of Decline in Small Fibre Function Assessed Using Axon Reflex-Mediated Neurogenic Vasodilatation and the Importance of Age Related Centile Values to Improve the Detection of Clinical Neuropathy https://pmc.ncbi.nlm.nih.gov/articles/PMC3723820/

I wonder if this systemic review paper might also be helpful for you:
- Corneal Confocal Microscopy to Diagnose Peripheral Neuropathy: A Systematic Review and Meta‐Analysis https://pmc.ncbi.nlm.nih.gov/articles/PMC12593550/

It sounds like you may be looking for input from medical experts. You may be able to inquire at Mayo Clinic Laboratories https://www.mayocliniclabs.com/customer-service/contacts