Log in to your VDL account

Login
Skip to Main Content

Veterinary Diagnostic Laboratory

Related Sites Looking for the college?
Menu

Testing Protocol and Sample Handling

Endocrinology

Select

For complete information about Endocrinology tests, specimen requirements, or submittal procedures please see our catalog of available tests. Please call 517.353.1683 if you have any questions about Endocrinology testing. For easy reference, please see the table below for tests, protocol, and special instructions/comments.

  • Test

    Protocol

    Special Instructions/Comments

  • ACTH Response Test, Cortisol
    For Dogs or Cats. Collect baseline sample. If using Cortrosyn, administer 5 ug/kg IV and obtain post sample 1 hr later. If using ACTH gel, administer 2.2 IU/kg IM and collect post sample at 2 hr for dogs, or 1 hr for cats.
    Separate samples and pipet into a plain tube within 30 min of collection. This test is used to diagnose hypoadrenocorticism, hyperadrenocorticism and to monitor trilostane or mitotane therapy. It is also the best adrenal function test for diagnosis of iatrogenic hyperadrenocorticism.
  • ACTH Response Test, Aldosterone
    Follow ACTH Response test protocol.
    Separate EDTA plasma and pipet into a plain tube within 30 min of sampling.
  • ACTH, Endogenous
    Fasting sample. Centrifuge EDTA tube immediately after collection, pipet plasma into a PLASTIC tube, freeze. EDTA plasma required.
    Endogenous ACTH is used to differentiate adrenal-based from pituitary-based hyperadrenocorticism. Diagnosis of hyperadrenocorticism using a LDDST or ACTH response test should be confirmed prior to eACTH determination.
  • Calcitriol, 1,25-Dihydroxyvitamin D
    Fasting sample. Allow serum to clot at room temperature for 30-60 min prior to separation. Centrifuge to separate serum and pipet into a plain tube.
    Avoid exposure to light. Calcitriol is used to: determine serum calcitriol levels, especially in cases of chronic kidney disease (typically there is a calcitriol deficiency in chronic kidney disease); monitor calcitriol therapy; help diagnose rare causes of osteomalacia, such as vitamin D receptor defects.
  • Combined Dexamethasone Suppression Test /ACTH Response Test
    For Dogs or Cats. Collect baseline sample, administer 0.1 mg dex/kg IV. Obtain second sample 2 - 4 hr later. Then follow ACTH Response Test protocol.
    Separate samples within 30 min of collection and pipet into a plain tube. This test is used to screen for hyperadrenocorticism. Some pituitary tumors will suppress normally with this high dose of dexamethasone. Followed by an ACTH response test.
  • Equine Dexamethasone Suppression Test
    For Horses. Collect baseline sample at approx 5pm; administer 20 mg dex/500 kg BW IM; Collect post samples 15 and 19 hrs later.
    Separate samples within 30 min of collection and pipet into a plain tube. This is the test of choice for diagnosis of equine hyperadrenocorticism.
  • Gastrin
    Fasting serum sample.
    May be falsely elevated if the animal is receiving cimetadine.
  • High Dose Dexamethasone Suppression Test (HDDST)
    For Dogs. Collect baseline sample, administer 0.1 mg dex/kg IV or IM. Obtain samples at 4 hrs and at 8 hrs post dexamethasone (total of 3 samples).
    Separate samples within 30 min of collection and pipet into a plain tube. This test is used to differentiate pituitary-based hyperadrenocorticism.
  • IGF-1
    Fasting not necessary.
    Provides indirect assessment of growth hormone production.
  • Insulin/Glucose Ratio
    Fasting sample. For glucose tolerance testing, obtain fasting sample, infuse glucose 1.0 g/kg IV over 30 sec, obtain post samples at 15, 30, 45, and 60 min.
    Separate serum within 30 min of collection and pipet into a plain tube. Used to diagnose insulinoma. Also used to document insulin resistance especially in horses.
  • Low Dose Dexamethasone Suppression Test (LDDST)
    For Dogs. Collect baseline sample, administer 0.01 mg dex/kg IM. Obtain samples at 4-6 hrs, and at 8 hr post dex (total of 3 samples).
    Separate samples within 30 min of collection and pipet into a plain tube. This test is used to diagnose hyperadrenocorticism and may differentiate pituitary-based hyperadrenocorticism. May be followed by an ACTH response test.
  • Malignancy Profile (PTH, ionized calcium, and PTHrP)
    Fasting samples. Allow serum to clot at room temp for 30 to 60 min prior to separation. Centrifuge EDTA tube and pipet plasma into a plain tube (label as plasma).
    Avoid lipemia and hemolysis. DO NOT SEND an EDTA tube without separating the plasma.
  • OFA Canine Thyroid Registry
    Fasting sample. See OFA website for sample handling requirements.
    Avoid hemolysis and lipemia. Owner must submit a separate check made out to OFA. Completed OFA application form must be enclosed. Animal must not have received thyroid therapy for 3 months prior. Results will not be available by telephone.
  • Parathyroid Profile, Basic (PTH and ionized calcium)
    Fasting sample. Allow serum to clot at room temp for 30 to 60 min prior to separation and pipet into a plain tube.
    Avoid lipemia and hemolysis.
  • Parathyroid hormone related protein (PTHrP)
    Fasting sample. Centrifuge EDTA tube and pipet plasma into a plain tube (label as plasma). EDTA plasma required.
    Avoid lipemia and hemolysis. DO NOT SEND an EDTA tube without separating the plasma.
  • Phenobarbital
    Take sample 2 or more hours post phenobarbital.
    Phenobarbital concentrations are slightly lower in samples in serum separator tubes. Steady state concentrations are reached after 2-3 wks of treatment.
  • Progesterone
    For ovarian remnant determination: Dog: sample 7-14 days after signs of estrus end; Cats: Sample 7-14 days after induction of ovulation by manual stimulation or giving HCG 500 IU/kg IM.
    Samples submitted for same-day progesterone assay must be received by 12:30 pm to have result reported on the same day.
  • T3 Suppression Test, Feline - Standard or Premium
    Collect baseline sample. Give 25 ug T3 (Cytomel) at 8 hr intervals for 6 or 7 treatments. Collect post sample 2-4 hrs after last treatment.
    Baseline serum sample may be kept refrigerated or frozen so that both samples may be shipped together.
  • Testosterone
    For Dog or Cat: baseline sample usually sufficient. Horse- baseline; 30 min, 1 and 2 hr post HCG injection (6000-12000 IU/horse IV or IM Dog GnRH Response test: baseline, 1 & 2 hr post GnRH 0.22 ug/kg IV
    A baseline sample is often adequate in dogs and cats. An HCG response test is often needed in horses.
  • Thyroid Profile, Canine (Diagnostic or Monitoring)- Standard or Premium
    For monitoring thyroid supplementation, collect sample 3-8 hr post pill & specify type of therapy, dose, & time post pill.
    Avoid hemolysis and lipemia.
  • Thyroid Profile, Feline or Other – Standard or Premium
    Timing of sample not important.
    Avoid hemolysis and lipemia.
  • Urinary Cortisol: Creatinine Ratio
    Have owner collect urine at home under non-stressful conditions.
    The urinary cortisol:creatinine ratio is a screening test for hyperadrenocorticism. It is also positive with stress, and in many nonadrenal illnesses.
  • Vitamin D, 25-hydroxy
    Fasting sample. Allow serum to clot at room temp for 30 to 60 min prior to separation and pipet into a plain tube.
    Avoid exposure to light. Measured if inadequate or excessive vitamin D ingestion is suspected.
  • Vitamin D Profile (PTH, ionized calcium, and 25-hydroxyvitamin D)
    Fasting sample. Allow serum to clot at room temp for 30 to 60 min prior to separation and pipet into a plain tube.
    Avoid lipemia and hemolysis.

Quantity Not Sufficient (QNS) Results

There are two situations in which a "Quantity Not Sufficient" will be reported instead of a result.

The first situation is that insufficient serum arrived at the laboratory. Please check up-to-date guidelines on sample volumes provided in our test catalog. Sometimes samples leak in transit, or tubes are crushed. If tubes are individually enclosed in sealed plastic bags, this can help salvage material after a leak.

The second situation in which we might report "Quantity Not Sufficient" is if one of our assays suffers a quality failure. The radioimmunoassay techniques we generally use in this laboratory are complex procedures susceptible to a number of factors which could affect their performance. For this reason, we have to verify the quality of the analysis before releasing results. If there is a quality failure and there is sufficient spare serum in the laboratory, we will just re-run the test. If there is not spare serum we would rather report “Quantity Not Sufficient” than an inaccurate or incorrect result. In some circumstances, therefore, you may have submitted sufficient volume for us to perform the analysis once, but not enough for us to recheck questionable results.

Turnaround Time for Results

Turnaround time depends on the tests ordered. Please see the test catalog for turnaround time for the test(s) you’re requesting. After samples arrive at the the MSU VDL, packages must be opened, samples sorted, and patient and sample information entered into the computer system. Samples are then transported to the lab. Depending on the time the package arrives, many thyroid profiles are started the same day. Some assays (such as the thyroid profile) take two days to complete the testing. Many of our tests are started early in the morning as they can be long assays, and if the sample arrives mid-day on the day we are running the test, chances are that the assay has already been started.

Overnight, On Ice Shipping for Premium Thyroid Profiles

Time and temperature can both have an effect on Free T4 by equilibrium dialysis (FT4d). Most thyroid hormone exists bound to proteins, and only a small percentage exists as free hormone. Once a sample is drawn, these proteins start to break down, releasing more free thyroid hormone. This process is accelerated with warm temperatures, and over time. This release of free hormone from the binding proteins can result in a ‘false’ increase in measured FT4 by equilibrium dialysis.