Journal Scan: Is there an easy screening test for canine hypoadrenocorticism?
Dogs with hypoadrenocorticism can have a range of clinical presentations that mimic other disease processes, so effective screening is beneficial when you suspect this endocrinologic disorder in a patient. Hypoadrenocorticism is diagnosed based on the results of an ACTH stimulation test. However, this test is not routinely performed unless there is a high level of suspicion.
A basal serum cortisol concentration is a simpler, less expensive screening tool. This method is highly sensitive but has low specificity and, thus, limited usefulness. A serum sodium:potassium ratio < 27 is suggestive of a mineralocorticoid deficiency but is not a highly sensitive or specific test for hypoadrenocorticism. Likewise, leukocyte parameters for dogs with hypoadrenocorticism generally fall within the normal reference ranges.
What they did
Study inclusion criteria
What they found
Furthermore, the results suggest that a patient’s absolute lymphocyte count at the time of initial evaluation represents an additional screening test that is more specific than the sodium:potassium ratio. Dogs with hypoadrenocorticism had significantly higher lymphocyte counts, although most were still within the reference range.
The finding that the sodium:potassium ratio is a less sensitive test than the lymphocyte count is consistent with previous research showing that electrolyte abnormalities, representing mineralocorticoid deficiency, occur in only 76% of hypoadrenocorticism cases.
Seth M, Drobatz KJ, Church DB, et al. White blood cell count and the sodium to potassium ratio to screen for hypoadrenocorticism in dogs. J Vet Intern Med 2011;25(6):1351-1356.