This was an email question from one of my telemedicine clients:
This was an email question from one of my telemedicine clients:
Does the “stress ” of an ultrasound interfere with results if done same day in your opinion? Never been asked that before today…
Andi Parkinson, RDMS
IntraPet Imaging, LLC
My response: Never been tested that I know of. Would make sense though.
This is what I quoted from an article she had forwarded to me to go over:
I said this is the concept most practitioners forget or have issues with re the LDDST
“The specificity of the LDDST can be low (40% to 50%), especially when measured in a population of sick dogs (4). Because of the low specificity of this test, diagnosis of Cushing’s syndrome should never be based on results of an LDDST alone, especially in a dog with nonadrenal disease. It is best to delay testing for hyperadrenocorticism until the dog has recovered from the concurrent illness (4).”
http://endocrinevet.blogspot.it/2012/05/helpful-tips-to-improve-accuracy-of-low.html?m=1
Her client had run an lddst without getting a urine spec grav first which is a big No No. You have to establish true PU/PD (I use USG < 1.020 repeatedly to be sure true PUPD is present) first unless chasing atypical like the endocrine panel U Tennessee.
But if looking for Hyper production of cortisol true PUPD has to be established… many mistake dysuria and pollakuria every day for PUPD so I am often pulling the Trilostane and Lysodren out of their hands often before making something Addisonian when a UTI or stone or urethral tumor is in play causing the clinical signs.Moreover there are many other causes of pupd… medullary washout, salty dietary indiscretion, renal failure, psychogenic PD, d insipidis and so on. So even if pupd is established and sap is up doesn’t mean the pupd is Cushings even with an LDDST + there are still some false + with other causes of PUPD … especially when adrenals are normal in size shape and contour ont he sonogram there is only a small % of normal adrenal dogs that are pdh… usually early pdh but its very important ot look for other things casuing the true pupd and sap rises with tons of possible non cushings sap inducers;… breeds (min schnauzers, huskies, other) age, tumors, fibrosis, mucoceles, other enocrinopathies, bone issues, Gi issues… the wind blowing a different direction..SAP is a very aspecific enzyme
So if you think of all the disease processes that occur in dogs of Cushing’s age then there is a lot to cause stress + on the LDDST. These dogs are often/nearly always carrying around something “stressful”.. pancreatitis, mucoceles, uti, neoplasia or orthopedic disease and pain… not to mention white coat effect.
So I pinged Remo Lobetti (http://sonopath.com/about/specialists/remo-lobetti-bvsc-mmedvet-phd-decvim) and of course “The Remo Manual” has an answer regarding the sonogram timing and the LDDST to answer my client’s question:
Abstract on the subject:
May ER, Frank LA, Hnilica KA, Lane IF. Effects of a mock ultrasonographic procedure on cortisol concentrations during low-dose dexamethasone suppression testing in clinically normal adult dogs. Am J Vet Res. 2004 65:267-270.
OBJECTIVE:
To determine whether the stress of an ultrasonographic procedure would interfere with the suppressive effect of dexamethasone during a low-dose dexamethasone suppression test (LDDST) in healthy dogs.
ANIMALS:
6 clinically normal adult dogs.
PROCEDURE:
In phase 1, an LDDST was performed 5 times at weekly intervals in each dog. Serum samples were obtained 0, 2, 4, 6, and 8 hours after dexamethasone injection. A mock 20-minute abdominal ultrasonographic examination was performed on all dogs at each time point during the LDDST on weeks 2 through 5. In phase 2, serum cortisol concentrations were measured before and immediately after a 20-minute mock abdominal ultrasonographic examination, as described for phase 1.
RESULTS:
We did not detect significant differences after dexamethasone injection when comparing median cortisol concentrations for weeks 2 to 5 (mock ultrasonographic procedure) with median concentration for week 1 (no mock ultrasonographic procedure). For 5 of the 6 dogs, cortisol concentrations after dexamethasone injection decreased to < 35.9 nmol/L after each mock ultrasonographic procedure and remained low for the duration of the LDDST. In phase 2, all dogs had significant increases in cortisol concentrations immediately after the mock ultrasonographic procedure.
CONCLUSIONS AND CLINICAL RELEVANCE:
A 20-minute mock abdominal ultrasonographic examination performed during LDDST did not alter results of the LDDST in most dogs. Cortisol concentrations measured immediately after a mock ultrasonographic examination were significantly increased. Ultrasonographic procedures should be performed a minimum of 2 hours before collection of samples that will be used to measure cortisol concentrations.
