Pituitary Endocrine Disorders Flashcards
OBJ: Know and understand the clinical signs and pathophysiology of Acromegaly
- Unregulated diabetes (PU/PD/PP)
- Broad face, prominent jowls
- Large body size
- thick skin on head, neck, limbs
- heart failure signs
- arthritis/arthropathy
OBJ: Know and understand the clinical signs and pathophysiology of Diabetes Insipidus (DI)
- excessive thirst
- water-seeking
- increase urine production
- encephalopathy
OBJ: Know and understand the key clinical and laboratory features of Acromegaly
- Hyperphosphatemia without azotemia
- Hyperglobulinemia
- elevated ALP and ALT
- Proteinuria/Hyposthenuria
- periarticular periosteal proliferation
- Hyperostosis of the skull
- Cardio-, hepato-, and renomegaly
OBJ: Know and understand the key clinical and laboratory features of Diabetes Insipidus
OBJ: Know and understand the diagnostic tests used to confirm Acromegaly
- Hormone assessment
- GH - not useful do to fluctuations and availability
- Insulin-like Growth Factor 1
- liver response to GH
- reflects GH 24hr prior - Elevated in Acro
OBJ: Know and understand the diagnostic tests used to confirm Diabetes Insipidus
- Monitor water intake for 24hr
- obtain serial plasma and urine osmolality
- Determine response to Osmotic stimulus and ADH
- Water deprivation test
- DDAVP response test (ADH analogue)
OBJ: Know and understand the treatment options for Acromegaly
- Radiation - TOC cats
- Hypophysectomy
- Medical management
- pasireotide
- supportive care
OBJ: Know and understand the treatment options for Diabetes Insipidus (DI)
- provide water
- intranasal DDAVP
- Monitor for over/under treatment
What is Acromegaly?
- “Hypersomatotrophism”
- Chronic excess GH secretion
- GH (growth hormone) aka somatotrophin
- Causes overgrowth of soft tissues, bones, and viscera (anabolic) and insulin resistance (catabolic
- RARE
What is the etiology of Acromegaly in cats?
- ACRO caused by GH producing pituitary tumor
- Macroadenoma of the pituitary somatotrophs
- Functional, benign tumor; locally expansive; rare distal metastasis
What is the etiology of Acromegaly in Dogs?
- Excess progestin compounds
- Exogenous or endogenous PROG stimulates GH secretion
- Medroxyprogesterone (MPA; Depo-Provera) most commonly implicated
What is the common signalment/history of patients with Acromegaly
- Geriatric males over-represented (mean age 10yo)
- Unregulated diabetes (PU/PD/PP) - historical or at initial presentation
What are the common physical exam findings of a patient with Acromegaly?
- Pronounced physical changes
- Broad face, prominent jowls
- Protruding jaw (prognathia), enlarged interdental spaces
- Large body size, distended abdomen
- Thick skin on head, neck, limbs (dogs)
- Weight gain (*despite diabetes mellitus)
- Heart failure signs (tachycardia, dyspnea)
- Arthritis/arthropathy
- Neurological signs (abnormal mentation, depression
Which hormones can be assessed for an Acromegaly diagnosis? which is the most useful?
- GH
- IGF-1 - MOST useful
Why isn’t GH as useful for diagnostics
- Should be most useful, but
- GH level fluctuates over the day and disease stage
- GH assays not regularly available
- GH level rarely determined in dogs and cats
Why is IGF-1 most useful
- IGF-1 is produced in the liver in response to GH
- IGF-1 level reflects GH secretion for 24 hr prior and is ELEVATED in Acromegaly
- Some poorly-regulated diabetic cats have elevated IGF-1 levels that overlap with Acromegaly cats
- very high level strongly suggests Acromegaly
- Feline and Canine IGF-1 assays are offered by several commercial labs
What Laboratory Findings are common for patients with Acromegaly?
- CBC - erythrocytosis
- CHEM:
- changes caused by diabetes - hyperglycemia, hypercholestrolemia
- Elevations in ALP and ALT
- Hyperglobulinemia
- Hyperphosphatemia without Azotemia
- Renal failure present in some cats: azotemia and hyperphosphotemia
- Urinalysis:
- Proteinuria
- Hyposthenuria
- Ketonuria is uncommon
What findings are common during imaging of patients with acromegaly?
- Enlarged soft tissues of head and neck
- Periarticular periosteal proliferation
- Elongated mandible
- Hyperostosis of the skull
- Cardio-, hepato- and renomegaly
What are the treatment options for Acromegaly?
- Radiation - TOC in cats
- mixed results; improvement over months
- Hypophysectomy
- some success w/ surgical removal of tumor; limited experience/availability
- Medical Management
- Pasireotide (somatostatin analogue) - shows promise in European studies $$$
- Others - bromocriptine, octreotide
- Not useful in cats
- Supportive therapy - address diabetes, heart failure, renal insufficiency
What is the prognosis for patients with Acromegally?
- Guarded to poor
- survival is 18 - 36 monthsd
How is Diabetes Mellitus regulated in cats with Acromegally?
- Same treatment principles as other diabetic cats
- Ketosis is uncommon
- Large doses of insulin may be needed
- May never get complete control
- Affected cats are at risk for DM complications
What is Diabetes Insipidus (DI)?
- RARE disorder
- Caused by ADH deficiency
- ADH - Anti-diuretic hormone (aka “AVP”)
- Produced from posterior pituitary
- Main hormone involved in water balance
- ADH deficiency = POLYURIA (increased urine volume)
What are the different types of Canine Diabetes Insipidus (CDI)?
- Complete - NO ADH secretion
- Partial - Insufficient amounts of ADH
What are the causes of Canine Diabetes Insipidus?
- Congenital - genetic/developmental
- Acquired - various causes
- intracranial tumor
- Metastatic tumor
- Infiltrative disease
- Infection
- Head trauma
- pituitary surgery
What are the clinical signs of CDI?
- Excessive thirst
- water-seeking behavior
- Increased urine production
- Encephalopathy - ill animals
- Signs of primary disease (acquired CDI)
What Laboratory findings are common in CDI?
- Hydrated animals:
- Typically normal
- Dilute USG (<1.008)
- Dehydrated animals:
- Hypernatremia (severe)
- Neurologic impairment
- Azotemia (pre-renal)
- Dilute USG (<1.008)
What are the common differential diagnoses for CDI?
- Primary Polydipsia (PP)
- young, hyperactive, excitable dogs
- Environmental/physical stressors
- Resolution occurs in novel situations
- Nephrogenic Diabetes Insipidus (NDI)
- Acquired water imbalance - secondary to other disorders (e.g. hypercalcemia, renal failure)
- “ADH” resistance
- Normal ADH productions
- Kidney is insensitive to ADH
How is CDI diagnosed?
- Quantitate 24-hr water intake
- Obtain serial plasma and urine osmolality
- Determine response to osmotic stimulus and ADH
- water deprivation test
- DDAVP response test (ADH analogue)
What is the treatment for CDI?
- Ensure adequate access to water at all times
- Intranasal DDAVP formulation
- 1 drop q12 hors into conjunctival sac
- Monitor to ensure patient is not over/under treated
What is the prognosis for CDI?
- Good for congenital CDI
- as long as the owner is aware and willing to treat
- Guarded/Poor for acquired CDI
- depends on primary pathology
What is the common signalment in dogs with acromegaly?
- Intact females (mean 7-8yo)
- young dogs receiving MPA
What history is common to dogs with Acromegaly
- Respiratory stridor, panting, fatigue
- Hx of MPA administration or estrus cycling
- Occasionally diabetes is present
- Less common: vaginitis, pyometra, skin and joint changes
How is acromegaly diagnosed in dogs?
- Based on history of progesterone exposure
What is the treatment for canine Acromegaly?
- Medical management (TOC)
- Discontinue exogenous progestin or perform ovariohysterectomy
- All organ and tissue changes are expected to resolve over time
- Diabetes in dogs with ACRO can resolve
- Diabetes never resolves in some dogs and insulin is needed for life
- Prognosis - good with appropriate therapy
What is Pituitary Dwarfism?
- “Hypopituitarism”
- Extremely Rare
- German shepherd dogs are most commonly affected
What is the etiology and pathology of Pituitary Dwarfism?
- Genetic defect - genes unknown
- Autosomal recessive in GSD - unknown in other breeds
- Histology:
- pituitary hypoplasia (anterior lobe)
- Pituitary cysts - may be cause for consequence of hypoplasia
What clinical signs are common in Pituitary dwarfism dogs?
- Growth retardation - noticed at a young age, concern about poor growth
- Hair/coat abnormalities - retained puppy coat; alopecia may occur over time
- Determatopathy - hyperpigmentation and dry skin/scaling
- Reproductive abnormalities - cryptorchidism and anestrus
- Normal activity with lethargy developing later in life
How is Hypopituitarism diagnosed?
- Requires measurement of abnormal GH secretion
- Basal GH level test - typically low but inconsistent (NOT recommended)
- GH stimulation test:
- assess GH secretion after injection of GH secretogogue
- Normal dogs = 2-4x increase
- Not widely available
- Ancillary Testing - needed for full patient evaluation
- Assess thyroid, adrenal, and reproductive function
- Pituitary imaging - Brain CT/MRI
- small pituitary/cystic structures
How is Hypopituitarism treated?
- Optimal = GH replacement
- Canine/Feline GH is not commercially available for hormone replacement
- Porcine GH has bee used for dogs
- Hypoglycemia and diabetes are potential side effects
- Progestins may provide alternative therapy - not studied
What responses are expected from treatment of hypopituitarism?
- Growth may occur - depending on the status of the growth plates
- Improvement in skin and coat
What is the prognosis of Hypopituitarism?
- Poor w/out treatment
- Guarded w/ treatment
