PART 2

DISEASES OF THE ENDOCRINE SYSTEM

HYPERPARATHYROIDISMHYPOPARATHYROIDISM

DISEASES OF THE PARATHYROID GLANDS

Thyroid/Parathyroid glands

1=normal thyroid gland2 and 3=parathyroid gland4=enlarged thyroid gland

Parathyroid gland

Secretion: Parathyroid hormone (PTH, Parathormone)

Function: ↑ plasma Ca2+ concentration 1. ↑ osteoclast activity 2. ↑ Ca++ absorption from GI tract 3. ↑ Ca++ reabsorption from kidney tubules

Hyperparathyroidism →hypercalcemia

Hypoparathyroidism →hypocalcemia

Hyperparathyroidism

Causes: 1º hyperparathyroidism—adenoma or carcinoma 2º hyperparathyroidism—poor diet; low Ca intake;

renal disease

Clinical signs: Many animals show no clinical signs signs occur as organ dysfunction occurs

urinary/renal calculi (high plasma Ca++) cardiac arrhythmias, tremors (Ca++

necessary for normal muscle contraction) Anorexia, vomiting, constipation weakness

Hyperparathyroidism

Dx:Routine chemistry panel

↑ blood Calcium (normal: ~8-10 mg/dl)) +/- ↓ blood Phosphorus

PTH assay normal PTH: dogs ~20 pg/ml, cats ~17 pg/ml In a normal animal: if blood Ca++ is high, PTH is low (neg feedback) 1º Hyperparathyroidism: Ca++ high, PTH elevated

Ultrasound of neck – enlarged glands, abdomen - uroliths

Hyperparathyroidism

Tx:1. Surgical removal of diseased parathyroid

Other options:2. Ultrasound-guided chemical (ethanol) ablation

3. Ultrasound-guided heat (laser) ablation

Post-Op Care:1. Hospitalize for 1 wk; ↓PTH may predispose animal to hypocalcemia2. Calcium therapy (oral tabs, liquid)3. Vit D supplements (promotes Ca intestinal absorption)

Hyperparathyroidism

Client Info1. Most hyperparathyroid animals show

no signs when first diagnosed2. Run yearly chem panels on all

normal, older animals

Hypercalcemia: Other causes

Causes Neoplasia (lymphoma, perianal

gland tumors) Renal failure Hypoadenocorticism Vitamin D rodenticide Drugs or artifacts

Clinical signs vary with cause PU/PD, anorexia, lethargy, vomiting,

weakness, stupor/coma (severe), uroliths

Hypercalcemia

Treatment Fluids: 0.9% NaCl

No Ca2+ containing fluids Diuretics (furosemide) Steroids

Complications Irreversible renal failure Soft tissue calcifications

Hypocalcemia

Causes:1. Puerperal Tetany (Eclampsia)—late gestation thru

post-partum perioda. Improper prenatal nutritionb. Heavy lactationc. Inappropriate Ca++ supplementation

2. Parathyroid diseasea. Inadvertent removal of parathyroid during

thyroidectomy (most common causeb. 1º Hypoparathyroidism (uncommon in animals)

3. Chronic renal failure—a. Vit D normally activated in kidneyb. Protein-losing nephropathy results in loss of albumin-bound

Ca

http://www.thepetcenter.com/gen/eclampsia.html#The_video

Hypocalcemia

Clinical Signs:1. Restlessness, muscle tremors,

tonic-clonic contractions, seizures 2. Tachycardia with excitement;

bradycardia in severe cases (Ca++ is necessary for proper muscle contractions)

3. Hyperthermia4. Stiffness, ataxic

Hypocalcemia

Dx:Total serum <6.5 mg/dl

Tx:1. IV infusion of 10% Ca gluconate

solution (monitor HR and rhythm during infusion)

2. Diazepam (IV) to control seizures3. Oral supplements of Ca (tabs, caps,

syrup)4. Improve nutrition

Hypocalcemia

Client info:1. Well-balanced diet; increase

volume as pregnancy progresses2. Signs in pregnant animal is

emergency; call vet immediately3. May recur with subsequent

pregnancies4. Early weaning is recommended

DIABETES MELLITUSINSULINOMA

EXOCRINE PANCREATIC INSUFFICIENCY

DISEASES OF THE PANCREAS

Review of pancreas functions

Long flat organ near duodenum and stomach

Exocrine function (the majority of the pancreas): Digestive enzymes

Endocrine function – islets of Langerhans Alpha cells => glucagon Beta cells => insulin Delta cells => somatostatin

Pancreas

Pancreas: beta cells

Review

Insulin Moves glucose into cells to be used for

energy Decreases blood glucose

Glucagon Raises blood glucose

Stimulates liver to release glucose Stimulates gluconeogenesis

Other hormones from other glands perform similar functions (hyperglycemic effect) Growth hormone Glucocorticoids

Insulin/Glucagon Balance

Endocrine Pancreas

Hyperglycemia Definition: Excessively high blood

glucose levels Normal in dogs: 60-120 mg/dl Normal in cats: 70 -150 mg/dl

Diabetes Mellitus

Definition: Disorder of carbohydrate, fat and protein metabolism caused by an absolute or relative insulin deficiency

Type I – Insulin Dependent DM – very low or absent insulin secretory ability

Type II – Non insulin dependent DM (insulin insensitivity) – inadequate or delayed insulin secretion relative to the needs of the patient

Diabetes mellitusIncidence:

Dogs: ~100% Type I (Insulin dependent)Cats: ~ 50% Type I and 50% Type II

-non-insulin dependent catscan sometimes be managed withdiet and drug therapy

Causes: Chronic pancreatitisImmune-mediated disease -beta cell destruction

Predisposing/risk factors:Cushing’s DiseaseAcromegalyObesityGenetic predispositionDrugs (steroids)

Diabetes mellitus

Age/sex: Dogs: 4-14 yrs, females 2x more likely

to be affected Cats: all ages, but 75% are 8-13yrs,

neutered males most affected

Breeds: Poodles, Schnauzers, Keeshonds, Cairn Terriers, Dachshunds, Cockers, Beagles

DIABETES MELLITUS

PathophysiologyInsulin deficiency => impaired

ability to use glucose from carbohydrates, fats and proteins

Impaired glucose utilization + gluconeogenesis => hyperglycemia

Diabetes mellitus

PATHOPHYSIOLOGY: Clinical signs develop when:

Exceeds capacity of renal tubular cells to reabsorb

Dogs – BG > 180-220 mg/dl Cats - BG > 200-280 mg/dl

Glucosuria develops Osmotic diuresis Polyuria/polydipsia UTI Suppress immune system

DIABETES MELLITUSSYSTEMS AFFECTED:

Endocrine/metabolic: electrolyte depletion and metabolic acidosis

Hepatic: liver failure 2° to hepatic lipidosis (mobilization of free fatty acids to liver leads to hepatic lipidosis and ketogenesis)

Ophthalmic: cataracts (dogs) from glaucoma

Renal/urologic: UTI, osmotic diuresis

Nervous: peripheral neuropathy in cats

Musculoskeletal: Compensatory weight loss

Diabetes Mellitus

Clinical Signs:PolyuriaPolydipsiaPolyphagiaWeight loss Dehydration Cataract formation-dogs Plantigrade stance-cats

Diabetes in Cats: Plantigrade posture

Diabetes Mellitus: Cataracts

Increase in sugar (sorbitol) in lens causes an influxof water, which breaks down the lens fibers

Diabetic Ketoacidosis

2 metabolic crises: ↑ lipolysis in adipose tissue → fatty acids →ketone bodies →ketoacidosis →coma (insulin normally inhibits lipolysis)↑ hepatic gluconeogenesis (in spite of high plasma glucose levels)

(insulin normally inhibits gluconeogenesis)

Diabetic Ketoacidosis

Definition: True medical emergency secondary to absolute or relative insulin deficiency causing hyperglycemia, ketonemia, metabolic acidosis, dehydration and electrolyte depletionDM causes increased lipolysis => ketone

production and acidosis

Diabetic Ketoacidosis

Diagnosed with ketones in urine or ketones in blood Can use urine dip stick with serum.

Clinical Signs All of the DM signs Depression Weakness Tachypnea Vomiting Odor of acetone on breath

Diabetic Ketoacidosis

IV fluids to rehydrate 0.9% NaCl Regular insulin to decrease

blood glucose Monitor BG q 2-3 hrs When BG close to normal and

patient stable switch to longer acting insulin

DIABETES MELLITUS

DIAGNOSIS: CBC: normal

Biochemistry panel: Glucose > 200 mg/dl (dogs), >250 (cats)

UA Glucosuria!!!! (causes UTI) Ketonuria USG – low

Electrolytes may be low due to osmotic diuresis

Fructosamine levels – mean glucose level for last 2-3 weeks (dogs) Ideal to test for regulation checks

Treatment: INSULIN AND DIET

Table 1. Traditional insulin outline.

Duration/onset category

Insulin types Concentration

Rapid acting Regular (Humulin R) U-100 (100 units/ml)

Intermediate acting NPH (Humulin N) U-100

Lente (Vetsulin® by Intervet)

U-40 (40 units/ml)

Long acting PZI (Idexx) U-40

Insulin Detemir U-100

Insulin Glargine U-100

Diabetes Mellitus: Insulin therapy

Diabetes Mellitus: Insulin therapy

Beef-origin insulin is biologically similar to cat insulin:

Porcine-origin insulin (porcine lente) is biologically similar to dog insulin

Dogs and cats have responded well to human insulin products protamine zinc insulin (human recombinant PZI)

Insulin Glargine: not approved for use in cats and PZI have same duration of action

DM: Insulin therapy

INSULIN ADMINISTRATION:ALWAYS USE THE

APPROPRIATE INSULIN SYRINGE! (U-40 vs. U-100) Insulin is given in units (insulin

syringes are labeled in units, not mL)

30 units, 50 units, 100 units

DM: dietary management

DIET DOGS: high fiber, complex carbohydrate diets

Slows digestion, reduces the post-prandial glucose spike, promotes weight loss, reduces risk of pancreatitis

Hill’s R/D or W/D

CATS: high protein, low carbohydrate diets Cats use protein as their primary source of

energyPurina DM, Hill’s M/D

Often a diet change in cats can dramatically reduce or eliminate the need for insulin This is particularly true for type II

Diabetes Mellitus

ORAL HYPOGLYCEMICS:o Sulfonylureas – Glipizide: cats

o Direct stimulation of insulin secretion from the pancreas

o Alpha-Glucosidase Inhibitors – Acarboseo Delays digestion of complex carbohydrates and

delays absorption of glucose from the intestinal tract.

Insulin is more effective than oral hypoglycemics

Diabetes Mellitus: Monitoring

Find an ear vein Prick the ear to get Place drop of blood blood sample on green tip; readout in

a few seconds

Diabetes Mellitus monitoring: Urine glucose

Diabetes Mellitus monitoring: Urine glucose

Diabetes Mellitus monitoring: Urine glucose

DIABETES MELLITUS

Client Education Lifelong insulin replacement therapy Insulin administered by injection Refrigerate insulin, mix gently (no

bubbles), single use syringes Vetsulin may require vigorous shaking

Consistent diet and exercise Recheck BG or curve regularly or

fructosamine levels if animal does not eat- NO INSULIN