EQUIN� ENDOCRINOLOGY

GROUP

Table 3 - Diagnostic testing: Resting insulin concentrations

Resting insulin concentration

Uses: Only use for identifying more severely affected animal (test has low sensitivity/high specificity)

Convenience sampling

Results

< 20 µU/mlb

20-50 µU/mlb

> 50 µU/mlb

Update: Fasting samples no longer recommended

After hay (no grain)

Do not feed grain within 4 hours

Collect into serum or EDTA tube

(check with laboratory)

While on pasture

Used to assess insulin concentrations

during grazingd

(assessment of current management)

Results must be interpreted in the context of the insulin assay used

(chemiluminescent assay, radioimmunoassay, or ELISA)

lnterpretationc

Non-diagnostic

ID suspect

Insulin dysregulation

Recommendation

Dynamic test recommended

to better assess

Proceed with ID management

• Assay should be validated for use with equine samples

b Cut-off values for lmmulite 1000; different values may be required for other assays or analyzers. For example, equivalent lmmulite 2000xpi

values are 31 and 80 uU/mL for 20 and 50 uU/mL, respectively

'Quality and NSC content of forages can vary and affect results; cut-off values are only applicable when horses are consuming low-NSC

carbohydrate hay

d Note that these values reflect the NSC content of the grass being consumed at the time of testing, which can change quickly and significantly

over time