Idexx SNAPshot Dx - Page 20

C-7
A. ACTH Stimulation Test
Pre-ACTH Interpretation
<2 μg/dL
(55.2 nmol/L)
Must evaluate in conjunction with post-ACTH result. If both
results are <2 μg/dL (55.2 nmol/L), results are consistent with
hypoadrenocorticism. Begin treatment with mineralocorticoid and/or
glucocorticoid as appropriate.
2–6 μg/dL
(55.2–165.6
nmol/L)
Normal
>22 μg/dL
(607.2 nmol/L)
Consistent with Cushing’s syndrome; perform high-dose
dexamethasone suppression test.
Post-ACTH Interpretation
<2 μg/dL
(55.2 nmol/L)
Ideally, should be evaluated in conjunction with pre-ACTH result. If
both results are <2 μg/dL (55.2 nmol/L) , results are consistent with
hypoadrenocorticism. Begin treatment with mineralocorticoid and/or
glucocorticoid as appropriate.
2–6 μg/dL
(55.2–165.6
nmol/L)
Inconclusive
6–18 μg/dL
(165.6–496.8
nmol/L)
Normal
18–22 μg/dL
(496.8–607.2
nmol/L)
Equivocal; Cushing’s syndrome possible
>22 μg/dL
(607.2 nmol/L)
Consistent with Cushing’s syndrome; perform high-dose
dexamethasone suppression test to discriminate between PDH and
ATH, ACTH level, and/or abdominal ultrasound.
B. Low-Dose Dexamethasone Suppression Test
4-Hour Cortisol Level 8-Hour Cortisol Level Interpretation
<1 μg/dL (27.6 nmol/L) <1 μg/dL (27.6 nmol/L) Normal
1–1.5 μg/dL
(27.6–41.4 nmol/L)
1–1.5 μg/dL
(27.6–41.4 nmol/L)
Inconclusive; consider repeating
in 6–8 weeks.
>1.5 μg/dL (41.4
nmol/L) and >50% of
baseline
>1.5 μg/dL (41.4
nmol/L) and >50% of
baseline
Consistent with Cushing’s
syndrome; perform high-dose
dexamethasone suppression test,
endogenous ACTH concentration
test, and/or abdominal ultrasound
to discriminate between PDH and
ATH.
<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) and <50% of
baseline
Consistent with PDH
SNAP Test Procedures