Increased blood levels of iron in horses with hyperinsulinemia

This is an interesting paper but of uncertain significance. Horses with equine metabolic syndrome and those with Cushings often have hyperinsulinemia. This paper finds these horses are also likely to have elevated blood levels of the bound iron ferritin and this condition is known as hyperferritinemia. Little is known about the significance of this in horses as well as humans where there have been some studies. In humans hyperferritinemia is associated with other diseases as seems to be thought of more as a result and not a cause though doubt exists. Horses generally have an excess of iron in the diet because it is prevalent in horses. We will watch this and see if this something that needs addressing.
DrO

Open Vet J. 2020 Jan;9(4):287-293. doi: 10.4314/ovj.v9i4.2. Epub 2019 Oct 21.
Possible dysmetabolic hyperferritinemia in hyperinsulinemic horses.
Kellon EM1, Gustafson KM1.

Author information:
1. Equine Cushing’s and Insulin Resistance Group, Inc, 2307 Rural Road, Tempe, AZ 85282, USA.
Abstract
Background:

Hyperinsulinemia associated with equine metabolic syndrome and pituitary pars intermedia dysfunction is a risk factor for laminitis. Research in other species has shown elevated body iron levels as both a predictor and consequence of insulin resistance. In humans, this is known as dysmetabolic hyperferritinemia.
Aim:

To explore the relationship between equine hyperinsulinemia and body iron levels.
Methods:

We reviewed case histories and laboratory results from an open access database maintained by the Equine Cushing’s and Insulin Resistance Group Inc. (ECIR). We identified 33 horses with confirmed hyperinsulinemia and laboratory results for serum iron, total iron binding capacity, and ferritin. Pearson correlation was used to test the relationship between insulin and iron indices. Additionally, we performed a secondary analysis of a previously reported controlled trial that was originally designed to test the correlation between iron status and the insulin response in horses. Here, we used a t-test to compare the mean values of insulin and ferritin between horses we categorized as normal or hyperinsulinemic based on their response to an oral challenge.
Results:

Serum ferritin exceeded published reference range in 100% of the horses identified from the ECIR database. There were no statistically significant associations between insulin indices (RISQI, log insulin) and iron indices (log serum iron, log TSI%, log ferritin). There were trends for a negative association between RISQI and log iron [r(31) = -0.33, p = 0.058] and a positive association between age and ferritin [r(30) = 0.34, p = 0.054]. From the secondary data analysis of published data, we found significantly elevated ferritin (p = 0.05) in horses considered hyperinsulinemic by dynamic insulin testing compared to horses with a normal response.
Conclusion:

These results suggest the potential for iron overload in hyperinsulinemic horses, a feature documented in other species and should stimulate further study into the relationship between insulin and iron dysregulation in the horse.