QUESTIONS

1. Explain how steroid hormones are able to effect action within cells.
    
2. There are three zones of the adrenal cortex.  Which layer is the outermost and which layer is responsible for aldosterone production?  Which layers produce cortisol?
    
3. What is the effect of corticosteroids on:
   
   a) hepatic gluconeogenesis?
   
   b) cellular uptake of glucose?
    
4. What is released into the hypothalamo-hypophyseal portal system to cause the release of ACTH by the adenohypophysis?
    
5. Of dogs with Cushing�s disease, what percentage have pituitary dependent disease and what percentage have adrenal dependent disease?
    
6. Of the dogs with pituitary dependent Cushing�s disease, what percent have microadenomas and what percentage have macroadenomas?
    
7. How big does a pituitary tumor have to be to be classified as a macroadenoma?
    
8. What is ectopic ACTH syndrome?
    
9. Explain the rationale behind the ACTH stim test.
    
10. Explain the rationale behind the low and high dose dexamethasone suppression tests.
     
11. How should the urine cortisol:creatinine ratio fit into the diagnosis of Cushing�s disease?
     
12. What percentage of adrenal tumors show calcification?
     
13. What volume per pound is considered normal water consumption in determining whether a pet is polydypsic.
    
14. What is �pseudomyotonia?�
     
15. How do corticosteroids induce a �stress leukogram?�
     
16. List the isozymes of alkaline phosphatase.
     
17. In using Lysodren, what are the chief complications to beware of?
     
18. What are the advantages and disadvantages of using Ketoconazole to treat Cushing�s disease?
     
19. Describe a typical protocol for the initiation of and maintainance on lysodren therapy.
     
20. What treatment options are available for pituitary macroadenoma?
     
21. What treatment options are available for adrenal tumors?
    
    
    
     

ANSWERS

1. The glucocorticoids exert their effects in responsive cells by getting absorbed into the cell & then binding w/an aporeceptor. They go together to the nucleus & influence transcription together.
   
   
   
   
    
2. The zona glomerulosa is the outermost layer & it is also the layer responsible for aldosterone production.  Zona fasciculata = the middle layer & the zona reticularis is the inner most. The innermost & middle layers produce cortisol.
   
   
   
   
    
3. Glucocorticoids increase hepatic gluconeogenesis but inhibit peripheral glucose uptake.
   
   
   
   
    
4. Corticotrophin-releasing hormone is the substance released into the hypothalamo-hypophyseal portal system.
   
   
   
   
    
5. 85% have pituitary disease, 15% have adrenal dependent disease.
   
   
   
   
    
6. Approximately 10% have macroadenomas.
   
   
   
   
    
7. Macrotumors are > 1 cm across.
   
   
   
   
    
8. Ectopic ACTH syndrome involves a tumor that secretes an ACTH-like substance. This phenomenon has not been documented in the dog but is usually due to lung tumors in humans.
   
   
   
   
    
9. When ACTH is delivered, the adrenal gland will dump its stored cortisol. A Cushing�s adrenal has a lot to dump & will produce a higher cortisol level than a normal adrenal can.
   
   
   
   
    
10. If you give a normal dog dexamethasone, the pituitary will cut ACTH production & 8 hours later, cortisol level will be suppressed.  If the dog has cushing�s disease, either the pit. tumor will be unaffected by the dex & no suppression will result or the adrenal tumor will not be affected by the loss of ACTH & will not suppress.
    
    In HDDS, there is so much dex being used that a pit. tumor actually will suppress.
    
    
    
    
     
11. The urine cortisol:creatinine ratio is a screening test only. If it is normal, cushing�s is ruled out.  If it is high, more testing is needed.
    
    
    
    
     
12. Approximately 50% of adrenal tumors will calcify.
    
    
    
    
     
13. A water consumption of 100 cc/kg (or 50cc/lb -1/5 cup per lb) would be considered polydipsia.
    
    
    
    
     
14. Pseudomyotonia is a rare myopathy that occurs in Cushing�s disease is characterized by persistent muscle contraction after a voluntary effort ends. dogs have pelvic limb stiffness & bizarre EMGs.
    
    
    
    
     
15. Increased PMNs & increased monocytes come from inducing demarginization & prevention of normal egress from the vasculature.  The decrease in eosinophils comes from induced marrow sequestration.  The decrease in lymphocytes comes from lysis.
    
    
    
    
     
16. The isozymes of ALP are: placental, bone, steroid induced, liver.
    
    
    
    
     
17. Chief problems w/lysodren = induction of Addison�s disease, temporary cortisol reductions leading to GI signs, or just reactions to the drug. It can even cause CNS signs as Opddd is related to DDT.
    
    
    
    
     
18. The advantages of ketoconazole include the lack of necessary ACTH stims on a regular basis. If you get side effects from keto, you just stop the drug & wait for side effects to go away.  Disadvantages = cost & that it must be given BID.
    
    
    
    
     
19. Typical induction is 50 mg/kg divided BID for approx. 9 days. ACTH stim confirms the endpoint of induction.  If ACTH is a flat line, the same dose is divided 2x per week. ACTH stims are due twice a year.
    
    
    
    
     
20. Pituitary macroadenomas are treated with radiation.  70% will show improved neuro function. Of these 50% will show rapid improvement & the rest improvement didn�t show up until a month or two. Radiation may or may not control the Cushing�s disease, too.
    
    
    
    
     
21. Treatment options for adrenal tumors include surgery or high doses of lysodren.