Re: Frodo - Radiographs, Iron Panel Results - in Flare-Up

Kirsten Rasmussen

Hi Becky,

The only calc to do is Transferrin Index:
(Serum Fe ÷ TIBC) × 100

For information on iron overload, see this link:,%20Iron%20Testing,%20Iron%20Overload/Iron%20-%20Dr.%20Kellon%20on%20Iron%20Overload.pdf

Specifically this message on normal ranges:
The tests in an iron screen are:
1. Serum iron - the amount of iron circulating in the blood. This primarily reflects the amount the horse is absorbing from his diet. Upper normal is between 150 and 190 for most labs.
2. TIBC - Total iron binding capacity. This is a measure of transferrin, a protein in the blood that binds and carries iron. Free iron is very damaging to the tissues. TIBC normally increases as serum iron increases. Like serum iron, it can't be used as a measure of body iron load. KSU has reported seeing them as high as 455, but I have several higher than that, in both the normal and the IR group. Think of it as a "reaction" to the presence of iron in theblood, like insulin going up is a "reaction" to blood glucose.
3. TSI - Transferrin saturation index. This is a calculation, iron divided by TIBC x 100, that shows how much of the transferrin protein is saturated with iron. TSI does correlate with body iron burden, and also with how much iron is being absorbed. Upper normal is somewhere in the low 40s.
4. Ferritin - This is the protein that binds iron in the tissues and has been proven in horses to correlate very well with body iron burden. It can also be elevated with inflammation, malignancy, severe trauma, etc. but in that case the serum iron and TIBC go down. Horses in the IR study that were actively laminitic and showed the pattern of high ferritin but low iron and TIBC were not included so that there would be no false elevation of ferritin values. Serum ferritin of normal horses in Dr. Smith's study showed a mean of 152 with a standard deviation of 54.6, which means 152 was the average and most (95%) of the horses fell within a range of 97.4 to 206.6. My normals were similar, 139 plus or minus 43.9.
If the supplement contributed to this laminitis, you might have to do more than just remove it.  To stabilize Frodo again,  try separating him and soaking his hay for a few weeks.  My experience has been that after a laminitic flare-up I have to do more than just remove the apparent trigger for my horse.  Perhaps this is because my horse's 7% hay was borderline for him when fed dry, so soaking it makes the biggest difference.

I would separate and soak anyways if Frodo is still in pain.  All it takes is an electrified string and some push-in posts (or wood posts in buckets of solidified concrete) between him and his buddies, or some round pen panels if you have them. 

Also, following up on the ACTH testing.  Generalization: most IR horses are ravenous and not picky eaters.  If he is being picky then maybe that's another sign of PPID having a role in this.  Interesting that the rest of the herd is picky, too!

Kirsten and Shaku (IR + PPID) - 2019
Kitimat, BC, Canada
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