Pituitary dysfunction Flashcards

Question

Thyrotropin (TSH) Elevation

Answer 1

Secondary | Thyrotropin secreting pituitary tumor-very rare (

Answer 2

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 (>80% macroadenomas)

Answer 3

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 4

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 5

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 6

GH, LH/FSH->TSH, ACTH->PRL

Answer 7

-similar presentation to target gland hormone deficiency, with some exceptions: -Primary adrenal insufficiency also presents with hyperkalemia from mineralcorticoid deficiency and hyperpigmentation from ACTH excess. Diagnosis: Basal and Dynamic Testing

Answer 8

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 9

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 10

Depends on the severity of hyponatremia and the rapidity of development (acute,

Answer 11

Criteria - Hyponatremia (Na+ 135 mmol/L) (hypotonic plasma (100mOSm/kg)with normal renal fcn - Euvolemic Status (no orthostatics hypotension) - Exclusion of other potential causes of euvolemic hypo-osmolality - ---Hypothyroidism - ---Hypocortisolism

Answer 12

Identify and Reverse Underlying Disorder (when possible) Tx depends on the severity of hyponatremia Mild-to-Moderate Hyponatremia (Na+ ~120-134 mmol/L) - Water Restriction (500-1000L/24hrs) - V2 Receptor Antagonists ($$$) - Salt tablets, Lasix, Urea (Europe) ``` Severe Hyponatremia (usually Na+ = 120mmol/L) -hypertonic saline ```

Answer 13

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 > 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 14

Nephrogenic DI 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 Neurogenic DI 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 15

Classic Triphasic Response: 1° phase– DI-polyuric phase due to axonal shock/decreased AVP release (days 1-5) 2° phase – SIADH from degenerating neurons/excessive AVP release (days 6-11) 3° phase-Permanent DI after depleted ADH stores and if >80% AVP neuronal cell death Permanent DI-uncommon complication with an experienced neurosurgeon (

Answer 16

*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)