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M6 13-005
Exam 13: Pituitary Disorders
Term | Definition |
---|---|
Pituitary Gland | The "Master Gland". Controls and communicates the functions over other endocrine glands through the negative feedback system. |
Hormones | Chemical in nature and are considered messengers. |
Anterior Pituitary (adenohypophysis) releases | GH (Growth Hormone). TSH (Thyroid Stimulating Hormone). ACTH (Adenocorticortropin Hormone). FSH (Follice Stimulating Hormone)& LH (Luteinizing Hormone). MSH (Melanocyte Stimulating hormone). Prolactin. |
GH (Growth Hormone) | Bone, cartilage, muscle and organs. 1) Accelerates anabolism of proteins and catabolism of fats. 2) Slows catabolism of carbohydrates (glucose). |
TSH (Thyroid Stimulating Hormone) | Thyroid & Parathyroid |
ACTH (Adenocorticortropin Hormone) | Adrenal Cortex |
FSH (Follicle Stimulating Hormone) & LH (Luteinizing Hormone) | Female |
MSH (Melanocyte Stimulating Hormone) | Skin. Pineal Gland |
Prolactin | Mammary glands |
Two Parts of Pituitary Gland | Anterior Pituitary. Posterior Pituitary |
Posterior Pituitary (Neurohyophysis) release | ADH (Anti-diuretic Hormone. Kidney tubules. Also called vasopressin). Oxytocin (uterus smooth muscles and mammary glands). |
Acromegaly | Overproduction of somatotropin (growth hormone or GH) in the adult. Caused by idiopathic hyperplasia of the anterior pituitary gland or tumor growth. Common signs are enlarged hands and feet. Irreversible. |
Acromegaly Dx Evaluation | Pt Hx and Clinical Manifestations. CT scan, and cranial radiographic evaluation. Lab tests to confirm ↑ serum Growth Hormone (GH) Levels: ↑ levels of serum GH, ↑ plasma insulin-like-growth factor-1. |
Meds for Acromegaly | Dopamine Agonists: (Cabergoline [Dostinex], Bromocriptine mesylate [Parlodel]). Octreotide (Sandostatin): Antagonizes the effects of natural GH by inhibiting the release of GH. |
Sx Tx for Acromegaly | Trasphenoidal Hypophysectomy; removal of tumor tissue through the nose. Irradiation w/ proton beam therapy to destroy tumors. |
Gigantism: Causes | Over secretion of GH results from hyperplasia of the anterior pituitary. Defect in the hypothalamus, which releases more GH. |
Dx test for Gigantism and Acromegaly | GH supression test AKA "Glucose-loading test". Reveals ↑ baseline GH levels. Criterion standard: The inability to supress serum GH level. |
Dwarfism: Cause | Deficiency in growth hormone. Most cases are idiopathic. Small amount attributed to autosomal-recessive trait. Some cases show lack of ACTH, TSH & gonadotropins. |
Dwarfism Assessment | Pt understanding of disease process. Family Hx. Determine when growth retardation was 1st noted. |
Dwarfism Evaluation | ↓ plasma levels of growth hormone is considered the definitive diagnosis. NPO after midnight. |
Dwarfism: Medical Management | Replace GH by injetion. Replace other specific hormones as needed to correct deficiencies. |
Diabetes insipidus | Disorder of the posterior pituitary in which ADH is deficient. |
Diabetes Insipidus: Causes | Primary (malfunction of the posterior pituitary). Secondary to other conditions. Infections (encephalitis or meningitis). ↓ in ADH results in electrolyte imbalance. -↑ plasma osmolatlity. -↑ urianry output. |
Diabetes Insipidus: Manifestations | Marked polyuria. Intense Polyuria. Severe hydration. Hypernatremia. |
Low Specific Gravity | 1.001-1.005 |
Urine specific gravity | < 1.003 (normal 1.005-1.030) |
Serum sodium level | > 145 mEq/L (normal 135-145 mEq/L) |
Serum osmolality | may be >300 mOsm/kg (normal 280-300) |
Water deprivation test | How well pituitary is working and rule out other causes. Patient is deprived of fluid intake and urine output is monitored. |
Dibetes Insipidus: Medical Management | Aqueous vasopressin (pitressin). DDAVP (Desmopressin) |
Aqueous Vasopressin (Pitressin) | 1) Increases water resorption in distal tubules and collecting ducts of nephron. 2) Concentrates urine, reducing water excretion by up to 90%. 3) Causes potent vasoconstriction in large doses. |
DDAVP (Desmopressin) | 1) Synthetic drug with ADH activity that will reduce urine output to 2-3 L/24 hours. 2) Monitor for the following side effects: dizziness, hypotension, nausea, blurred vision/diplopia, or palpitations. |
Syndrome of Inappropriate Antidiuretic Hormone (SIADH) | Pituitary releases too much ADH. Kidneys reabsorb more water. Urine output decreases. Circulating volume expands. Results in: -Hyponatremia. -Hemodilution. -Fluid overload without peripheral edema. |
SIADH: Causes | Pituitary gland releases too much ADH. In response to ADH, the kidneys reabsorb more water. Urine output decreases. Circulating volume expands. Results in hyponatremia, hemodilution, and fluid overload without peripheral edema. |
SIADH: Risk factors (Medications) | 1) General anesthetics. 2) Opiates. 3) Barbiturates. 4) Thiazide diuretics. 5) Oral hypoglycemic. 6) Oxytocin. |
SIADH: Risk Factors (Malignancies) | 1) Oat-cell cancer of the lung. 2) Duodenal cancer. 3) Pancreatic cancer. |
SIADH: Risk Factors (Non-Malignant Pulmonary Diseases) | 1) Tuberculosis. 2) Lung abscess. 3) Pneumonia. |
SIADH: Risk Factors (Nervous System Disorders) | 1) Head trauma. 2) Cerebrovascular thrombosis. 3) Cerebral atrophy. 4) Acute encephalitis 5) Meningitis. 6) Guillain-Barre syndrome. |
Hyponatremia | (Na <135 mEq/L though serious symptoms do not appear until Na reaches 125 mEq/L). |
Water Intoxication: S&S | Hyponatremia. Diarrhea. LOC changes. Deep tendin reflexes will diminish. ↓ UOP. Weight gain. |
SIADH: Diagnosis | Hyponatremia (Sodium < 134 mEq/L). BUN/Creatinine is low to normal. Urine specific gravity > 1.032. urine sodium will be elevated. |
SIADH: Medical Management | Fluid restriction. Electrolyte management. Medication regimen. Declomycin. Lithium Carbonate. Eliminate cause. |