Pituitary Gland Dysfunction Flashcards

Question

Central Adrenal Insufficiency (AI)

Answer 1

Etiologies of Secondary/Tertiary AI Suppression of the HPA axis: S/p tumor resection for Cushing’s Syndrome (pituitary, ectopic or adrenal) Supraphysiologic exogenous glucocorticoid use (most common) greater than 5-7.5 mg prednisone (or equivalent glucocorticoid dose) for >1 month Drugs: Opioids and megace Hypothalamus/Pituitary Diseases and/or their treatments. Other-Isolated ACTH deficiency (very rare)

Answer 2

Fatigue Anorexia, nausea/vomiting and weight loss Generalized malaise/aches Scant Axillary/Pubic hair (DHEA-S dependent in females) Hyponatremia and Hypoglycemia

Answer 3

Basal testing: random am cortisol level, less than 3 ug/dl is AI, greater than 18 excludes AI Stimulation tests: insulin induced hypoglycemia (gold standard) Cosyntropin (synthetic ACTH) stim test valid for assessing HPA axis only if prolonged loss of pituitary signaling and resulting adrenal atrophy

Answer 4

``` high FSH/LH: Hypergonadotropic Congenital Anorchia Klinefelter's syndrome Testicular injury Autoimmune testicular dz glycoprotein tumor (rare) ``` Low FSH/LH Hypogonadotropic hypogonadism Hypothalamic/pituitary diseases: macoedemas, prolactinomas, XRT Isolated GnRH deficiency Hemochromatosis Functional deficiency: critical illness, OSA, starvation, Meds-opiates, glucocorticoids

Answer 5

``` novulatory cycles oligo/amenorrhea, infertility Vagina dryness, dyspareunia Hot Flashes Decreased libido Breast atrophy Reduced bone mineral density ```

Answer 6

Reduced libido Erectile dysfunction Oligospermia or azoospermia Infertility Decreased muscle mass, testicular atrophy and decreased BMD Hot flashes with acute and severe onset of hypogonadism

Answer 7

- majority of FSH/LH tumors are clinically silent - rare presentations: ovarian hyperstim syndrome (F) or macro-orchidism (males) Middle aged pts (m greater than f) with macroadenomas and related mass effects (HA, vision loss, CN palsies, and or pit hormone def)

Answer 8

Blood tests: usually low FSH/LH, T/E2 Pituitary MRI Immunohistochemical analyses (+FSH, LH, or ASU staining) of the resected tumor

Answer 9

Etiologies: secondary Thyrotropin secreting pituitary tumor very rare (less than 1% of pit tumors) thryoid hormone resistance

Answer 10

Clinical Presentation Thyrotropinoma (TSHoma)-similar clinical presentation to primary hyperthyroidism (e.g., goitre, tremor, weight loss, heat intolerance, hair loss, diarrhea, irregular menses) but also with associated mass effects (e.g., headaches, vision loss, loss of pituitary gland function) from macroadenoma. Diagnosis Elevated Free T4 and a non-suppressed TSH Pituitary MRI (greater than 80% macroadenomas)

Answer 11

Etiologies Pituitary/Hypothalamic Diseases and/or their treatments Critical Illness/Starvation-Euthyroid Sick Syndrome Congenital defects (TSH-beta mutations, PROP1, POUF1 mutations). Pediatric onset Drug induced-supraphysiologic steroids, dopamine, rexinoids. Clinical presentation: similar to primary hypothyroidism (e.g., fatigue, weight gain, cold intolerance, constipation, hair loss, irregular menses). Possible mass effects Diagnosis: Low Free T4 levels in the setting of a low or normal TSH

Answer 12

Definition: Deficiency of 1 or more pituitary hormones. Panhypopituitarism=loss of all pituitary hormones Etiologies: Congenital-Genetic Diseases (transcription factor mutations) Acquired-Pituitary Lesions and/or their treatments (75%) Macroadenomas/Pituitary Surgery/Radiation Therapy Infiltrative/Infectious/Granulomatous diseases Traumatic Brain Injury/Subarchnoid Hemorrhage Apoplexy

Answer 13

Definition: Clinical syndrome of headache, vision changes, ophthalmoplegia and altered mental status caused by the sudden hemorrhage or infarction of the pituitary gland. Occurs in ~10-15% of pituitary adenomas; sub-clinical disease is more common Diagnosis: Pituitary MRI or CT Treatment Emergent surgery is indicated for evidence of severe vision loss, rapid clinical deterioration, or mental status changes. Stress dose steroids for adrenal insufficiency.

Answer 14

predictable loss of anterior pituitary hormones ADH deficiency common with metastatic tumors (breast, lung, or GI) or craniopharyngiomas, but not pituitary adenomas

Answer 15

-depends on severity -similar presentation to target gland hormone def w/ exceptions: Primary adrenal insufficiency also presents with hyperkalemia from mineralcorticoid deficiency and hyperpigmentation from ACTH excess. Dx: basal and dynamic testing

Answer 16

Treatment of Anterior Pit. Hormone Deficiencies (End Organ Hormone Replacement): Thyroid – Multiple L-thyroxine formulations available. Adrenal – Physiologic hydrocortisone or prednisone Medic Alert Bracelet, Sick day rules for glucocorticoid replacement No mineralcorticoid replacement needed Gonadal – Various formulations-oral/transdermal E2, transdermal/IM Testosterone Gonadotropin or pulsatile GnRH therapy Growth Hormone Various Formulations of subcutaneous shots (not orally active). Prolactin – SQ formulation, research purposes only.

Answer 17

-assoc with disorders of AVP (arginine vasopressing) = ADH antidiuretic hormone Release controlled primarily by high osmolar states via hypothalamic osmoreceptors ADH release also controlled by hypovolemia (baroreceptors)

Answer 18

V1: vascular vasoconstriction, platelet aggregation V2: antidiuretic effects in kidney adenylate cyclase activation leads to movement of aquaporin water channels to the cell membrane leads to water reabs

Answer 19

Definition: A syndrome of inappropriate AVP release/action in the absence of physiologic osmotic or hypovolemic stimulus. Hallmark is the excretion of inappropriately concentrated urine in the setting of hypo-osmolality and hyponatremia. SIADH is one of the most frequent causes of hyponatremia, and occurs in an estimated: 15-22% of hospitalized patients 5-7% of ambulatory patients

Answer 20

Major Categories: Malignant Disease- Carcinoma, Lymphoma, Sarcomas Pulmonary Disorders-Infections, Asthma, Cystic Fibrosis, Positive Pressure Ventilation CNS Disorders-Infection, Tumors, Trauma, Bleeds Drugs-Stimulate/Potentiate AVP release/actions Narcotics, Nicotine, Anti-psychotics, Carbamazepine, Vincristine Miscellaneous-Nausea, Stress and Pain

Answer 21

- depends on severity/rapidity of devel - Manifests with neurological symptoms from osmotic fluid shifts and brain edema ``` Plasma Na 130-135: asx 125-130: anorexia, n/v, HA, irritable 115-125: altered sensorium, gait disturbance less than 115: seizure, coma, death ```

Answer 22

Hyponatrema (Na less than 135 mmol/L) and hypotonic plasma osmolaltiy (less than 275 mOsm/kg) Inapp urine conc (urine osm greater than 100) with normal renal func euvolemic status exclude other potential causes of euvolemic hypo-osmolality Hypothyroidism Hypocortisolism

Answer 23

Identify and Reverse Underlying Disorder (when possible) Treatment depends on the severity of hyponatremia, the rate of development and the patient’s symptomatology ``` Mild-to-Moderate Hyponatremia (Na+ ~120-134 mmol/L) Water Restriction (500-1000L/24hrs) V2 Receptor Antagonists ($$$) Salt tablets, Lasix, Urea (Europe) ``` Severe: usually Na less than 120 mmol/L Hypertonic (3%) Saline-if patient is symptomatic (delirium/seizure/coma)

Answer 24

Limit Correction of Chronic Hyponatremia: less than 12 mmol in the first 24 hrs. Slower correction with other risk factors associated with osmotic demyelination syndrome Hypokalemia, alcoholism, poor nutritional status NO LIMITATIONS with acute onset hyponatremia (eg less than 48 hr onset, marathon runners)

Answer 25

Definition-DI is a syndrome of hypotonic polyuria as a result of either: Inadequate ADH secretion Inadequate renal response to ADH Hallmark-Voluminous (Urine output greater than 40ml/kg/d) dilute urine Main Causes: Central Diabetes Insipidus Nephrogenic Diabetes Insipidus Pregnancy-increased ADH metabolism from placental vasopressinase, but is generally not clinically relevant Primary Polydipsia Clinical Significance: Can lead to severe dehydration if thirst mechanisms are impaired, or if the patient has limited access to water.

Answer 26

nephrogenic vs neurogenic

Answer 27

Congenital: X-linked recessive AVP V2 receptor gene mutation; autosomal recessive aquaporin-2 water channel gene mutation Drugs: demeclocycline, lithium, amphotericin B Electrolyte abnormalities: hypokalemia and hypercalcemia Infiltrative kidney diseases: sarcoidosis and amyloidosis Vascular disease: sickle cell anemia

Answer 28

Neoplasms: craniopharyngioma, metastatic pituitary disease (e.g., colon, breast, lung) Idiopathic:+AVP Ab Congenital defects: autosomal dominant AVP neurophysin gene mutation Inflammatory/Infectious/granuloma pituitary diseases: lymphocytic hypophysitis, histiocytosis, sarcoidosis Trauma/Vascular event: neurosurgery, TBI/deceleration injury

Answer 29

Classic Triphasic response: Primary phase– DI-polyuric phase due to axonal shock/decreased AVP release (days 1-5) Secondary phase – SIADH from degenerating neurons/excessive AVP release (days 6-11) Tertiary phase-Permanent DI after depleted ADH stores and if greater than 80% AVP neuronal cell death Permanent DI-uncommon complication with an experienced neurosurgeon Isolated Second (SIADH) Phase-More Common (~25%)

Answer 30

Confirm polyuria with 24 hr urine volume collection (normalized to creatinine) Exclude hyperglycemia (osmotic diuresis), renal insufficiency and electrolyte disturbances (K+/Ca 2+) Assess Urine and Plasma Osmolalities Consider Water Deprivation Test Pituitary Imaging (for suspected neurogenic DI)

Answer 31

Fluid restriction to stimulate ADH release Measure Uosm , Posm Serum Na+ and Urine output Urine concentration Response to dDAVP +/- ADH Level after mild dehydration

Answer 32

Anti-Diuretic Hormone Replacements First Line-dDAVP (nasal, oral or parenteral routes of administration) Longer half-life than ADH No Vasopressor Effect Second-Line-ADH (IV, SQ or IM routes of administration). Goals: Resolution of Polyuria/Polydipsia Minimal disruption of sleep/daily routine Normal Serum Sodium

Pituitary Gland Dysfunction Flashcards

(56 cards)