Defining the regenerative stage of an anemia is an important step in analyzing the cause and deciding on the therapy and prognosis. The degree of regeneration classically has been determined by a number of methods including: percentage of reticulocytes, corrected reticulocyte percentage, and reticulocyte production index. These are all calculations based on a subjective review and manual count by the technologist.

More accurate direct measurements of the absolute reticulocyte number are now available from state-of-the-art hematology analyzers, or by determining a manual reticulocyte percentage and multiplying it by the RBC count.

The absolute reticulocyte number is more easily and accurately interpreted than either the corrected reticulocyte percentage or reticulocyte production index, and can be easily compared on a daily or weekly basis to monitor the patient’s response to anemia.

Beginning September 1, 2001, Antech will report all reticulocyte counts for cats and dogs as absolute numbers. The normal (nonregenerative) ranges for cats and dogs will be:

    Cats < 45,000/uL
    Dogs < 60,000/uL

Significant elevations above these levels are necessary to classify an anemia as regenerative. If you have any questions about result interpretation, please don’t hesitate to call the Consult Line at 1-888-VET-INFO.

Elevated serum 17-hydroxyprogesterone (OHP) concentrations in response to ACTH administration have been reported in dogs with hyperadrenocorticism (HAC).

A recent study evaluated 23 dogs suspected of having HAC. Diagnosis of HAC was confirmed by resolution of clinical signs after medical therapy or by adrenal gland biopsy. All dogs had elevated OHP concentrations subsequent to ACTH administration, including 12 dogs with normal ACTH stimulation test results and 4 dogs with normal ACTH stimulation and LDDS test results.

Conclusion:
ACTH stimulation and LDDS tests remain the tests of choice for confirming a diagnosis of HAC. Measurement of OHP concentrations may help to confirm the diagnosis in dogs with normal ACTH stimulation and LDDS test results—the so-called atypical cases of HAC.

Submission Information:
The test requires 50 ul of serum collected 1 hour post-synthetic ACTH or 2 hours post-ACTH gel administration. The test can be added on to a previously submitted post-ACTH serum sample, as it is not necessary to measure resting (pre-) OHP concentrations. The test code is 85388.