LABOKLIN Service ID: 1186
| Diagnosis | - Clarification of PPID (Cushing’s disease)
- If the results of ACTH determination or of the Dexamethasone Suppression Test (low dose) do not correlate with the clinical findings or are inconclusive (TRH Stimulation Test with high sensitivity and specificity).
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| Material | EDTA plasma 2x 0.5 ml or 3x 0.5 ml (centrifuged immediately, pipetted off; cooled until arrival at the laboratory) |
| Execution | - First blood collection = baseline value
- Slow injection of 1 mg of TRH i.v. horses > 250 kg bdw (horses < 250 kg bdw: 0.5 mg)
- Second sample exactly 10 min post TRH injection = stimulation value
A third blood sample may additionally be taken 30 minutes after administration of TRH.
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| Parameter | ACTH |
| Method | Chemiluminescence assay (CLIA) |
| Species list | Horse |
| Duration | Reporting of results on the day the sample is received (Mon–Sat) |
| Assessment | - Cut-off value 10 min after stimulation: < 100 pg/ml;
Borderline: 100–220 pg/ml; positive: > 200 pg/ml - Cut-off value 30 min after stimulation: < 40 pg/ml;
Borderline: 40–90 pg/ml; positive: > 90 pg/ml - These values are valid for the months of January to June.
- The stimulation test is not recommended from July to December. However, if the result is negative during this period (< 100 pg/ml after 10 minutes, < 40 pg/ml after 30 minutes), a diagnosis of PPID is very unlikely.
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