Idexx SNAPshot Dx - Page 21

C-8
C. High-Dose Dexamethasone Suppression Test
4-Hour Cortisol Level 8-Hour Cortisol Level Interpretation
<1.5 μg/dL (41.4
nmol/L) or <50% of
baseline
>1.5 μg/dL (41.4
nmol/L) and >50% of
baseline
Consistent with PDH
>1.5 μg/dL (41.4
nmol/L) and >50% of
baseline
<1.5 μg/dL (41.4
nmol/L) or <50% of
baseline
Consistent with PDH
<1.5 μg/dL (41.4
nmol/L) or <50% of
baseline
<1.5 μg/dL (41.4
nmol/L) or <50% of
baseline
Consistent with PDH
>1.5 μg/dL (41.4
nmol/L) and >50% of
baseline
>1.5 μg/dL (41.4
nmol/L) and >50% of
baseline
Additional testing required to
differentiate PDH from ATH;
consider measuring plasma
ACTH levels and/or performing an
abdominal ultrasound.
D. Post-ACTH Stimulation Mitotane (Lysodren*) Monitoring
Loading
Dose Interpretation
Maintenance
Dose Interpretation
<1 μg/dL
(27.6 nmol/L)
Discontinue mitotane.
If dog is listless or ill,
administer maintenance
prednisone in tapering
dose for 2 weeks. If dog
is clinically healthy, do not
start prednisone, but start
low maintenance dose of
mitotane in 2 weeks.
<1 μg/dL
(27.6 nmol/L)
Discontinue mitotane.
If dog is listless or ill,
administer maintenance
prednisone in tapering
dose for 2 weeks. If dog
is clinically healthy, do not
start prednisone. Restart
mitotane maintenance
therapy in 2 weeks, but
reduce dose by 25%.
1–5 μg/dL
(27.6–138.0
nmol/L)
Begin maintenance
mitotane dosing (25–50
mg/kg per week with food
in divided doses); repeat
ACTH stimulation test in
one month.
1–5 μg/dL
(27.6–138.0
nmol/L)
Maintain current dosage;
repeat ACTH stimulation
test every 3–4 months.
>5 μg/dL
(138.0 nmol/L)
Continue mitotane
loading dose for 3–7
days; recheck 3–7 days;
observe for adverse
reaction.
>5 μg/dL
(138.0 nmol/L)
Increase weekly dose
or repeat loading dose
for 3–7 days; observe
for adverse reaction and
then increase weekly
maintenance dose.
Note: 1 μg/dL = 27.6 nmol/L
SNAP Test Procedures