Posterior-Pituitary-Syndrome by GerardLum

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Posterior Pituitary Syndrome

Roles                                                                            Syndrome of Inappropriate Secretion of ADH (SIADH)
                  ADH                                   Oxytocin
Control amount of H2O reabsorbed         Contraction of Uterus during Labour     Definition
Acts in Distal Portion of Renal Tubule   Stimulates Milk Flow from Breasts       Characterized by
•     Distal Convulated Tubule           (contraction of muscle fibres in milk   Excessive release of ADH from Posterior Pituitary
•     Collecting Duct                    ducts)                                  Results in Hyponatraemia, Fluid Overload
Retention of H2O (Not Solute)                                                    1° condition that results in Abnormal Handling of H2O
Dilutes Blood (↓ [Na])                                                           Not excessive Solute Loss

Diabetes Insipidus (DI)                                                          Causes
                                                                                 Meningitis
Definition                                                                       Lung Cancer
Characterized by                                                                 Head Trauma
Excessive Thirst                                                                 Brain Tumour
Excretion of ↑ amou nts of severely Diluted Urine                                Drugs
(↓ Fluid Intake having no effect)
Due to                                                                           Pathophysiol ogy
Inability of Renal Tubular Cells to Reabsorb H2O properly from Urine                       Release of ADH not Inhibited by ↓ in Plasma Osmolality
                                                                                                  (When H2O Intake, Osmolality of Plasma ↓)
Classification                                                                                                         ↓
           Central/ Neurogenic                        Nephrogenic                                     ↓ Na Detected (laboratory testing)
Insuffi cient Production, Secretion of   Lack of Kidney response to normal                               (Na is main solute in Plasma)
ADH                                      levels of ADH                                                                 ↓
Result from damage to pituitary gland    Caused by                                                                  SIADH
Caused by                                •     Drugs
•      Brain Injuries                    •     Chronic Disorders                 Symptoms
•      Genetic Disorders                        o Kidney Failure                 Nausea
                                                o Sickle Cell Disease            Vomiting
                                                o Polycystic Kidney Disease      Irritability
                                                                                 Personality changes
Pathophysiol ogy                                                                 •     Combativeness
        Central/ Neurogenic                            Nephrogenic               •     Confusi on
           Destruction of                       Vasopression Receptors           •     Hallucinations
           Hypothalamus                       (Aquaporin-2 H2O channels)         Seizures
  Hypothalamus-Hypophyseal Tract              Acquired sensitivity to drugs      Stupor
         Posterior Pituitary                                ↓                    Coma
                 ↓                         Loss of Kid ney’s Response to ADH
        ↓ Secretion of ADH                                  ↓                    Treatment
                 ↓                              ↓ Reabsorption of H2O            Fluid restriction
      ↓ Reabsorption of H2O                from Urine at Renal Tubular Cells     IV Saline
  from Urine at Renal Tubular Cells                         ↓                    Drugs
                 ↓                                     Dilute Urine              •     Demeclocycline
            Dilute Urine                                 Polyuria
                                                                                 •     Conivaptan
              Polyuria                                  Polydipsia
                                                                                 •     Tolvaptan
             Polydipsia

Causes
Head Trauma
Surgery
Tumour
Tuberculosis
Meningitis
Sarcoidosis
Family Hereditary

Symptoms
Urinary Frequency
Nocturia
Enuresis
Pale Urine

Treatment
Adequate Hydration
       Central/ Neurogenic                           Nephrogenic
Desmopressin                             Diuretic Hydrochlorothiazide
Carbamazepine

								
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