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SpR Topic: Hyponatraemia

SpR Topic: Hyponatraemia. Jamilla Hussain ST3 April 2012 St. Catherine’s Hospice. AIMS. 2 Case study Definition Pathogenesis Epidemiology. Case 1: SM. 39 year old female A+E: fatigue, headache, nausea and vomiting, and profound weight loss ~ 1/12 OE: nil acute

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SpR Topic: Hyponatraemia

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  1. SpR Topic:Hyponatraemia Jamilla Hussain ST3 April 2012 St. Catherine’s Hospice

  2. AIMS • 2 Case study • Definition • Pathogenesis • Epidemiology

  3. Case 1: SM • 39 year old female • A+E: fatigue, headache, nausea and vomiting, and profound weight loss ~ 1/12 • OE: nil acute • Ix: Na 115, CXR: RUL mass, enlarged mediastinum • Seen by KC - Admitted

  4. CLINICAL ASSESSMENT

  5. Hx and Examination • VOLUME STATUS • CAUSES • SEVERITY

  6. Volstatus:Causes

  7. Severity

  8. Investigations-

  9. Plasma Osmolality < 280

  10. Essential Criteria for SIADH • Plasma Na<135mmol/l • Urine osmolalilty >100mOsm/kg • Urine Na >20 mmol/l • Euvolaemic • Exclusion of glucocorticoiddefficiency • Normal salt intake • Euvolaemic, urine Na>20, repeat Na 113

  11. Management

  12. Management of acute hyponatraemia + severe symptoms • Acute <48 hours • Fall >0.5mmol/l per day • Mortality 5-8% • IV hypertonic saline solution • 1.8% Saline = 0.3mmol/l Na • 1ml/kg body weight/hour • Aim 0.5mmol/l per hour correction • No more than 4-6 mmol/12 hr, stop >120mmol/l

  13. Central pontinemyelinosis • Balance risk of mortality with low Na with risk of irreversible myelinosis • 1-2 days post correction • Coma, confusion • Quadraparesis • CN defects, bulbar palsy (pons) • Cerebral irritation by low Na can produce irreversible brain damage, therefore hypertonic solution is life saving/brain preserving • 2 hourly assessment of Na • Worse if chronic/alcoholic

  14. SM • Infusion on ward whilst waiting transfer • Deteriorated rapidly on ward • Spoke to consultant • Opted for supportive care + uninterrupted time with children

  15. Definition • Na < 136mmol/l • SIAD more appropriate (15% no vasopressin) • Concentrated urine + hypo-osmolar plasma suggest abnormal free water excretion

  16. Physiology • Vasopressin gene on Ch. 20 • Peptide produce Arginine vasopressin (AVP) + vasopressin-specific neurophysin II (NP II) • HypothalamusPost. PituitaryAVP + NPII • 3 AVP receptions, V2 on renal CD • AVP binds V2c-AMPinserts AQP2 • Acquaporin water channels into apical plasma membrane CD • Allow passage of free water but not ions

  17. Epidemiology • Stimulation of HPA • Distal nephrons • Paraneoplastic -tumour secretes ectopic AVP - OR vasopressin-like peptide

  18. Epidemiology • Commonest SCLC, carcinoid • Pancreatic, oesophageal, prostatic, haematological • 523 SCLC- 9%SIAD • 32% ↑ AVP, 53% renal handling abnormal • Prognosis and response same +/- SIAD • Incomplete restoration of renal handling

  19. Other causes • Drugs: Opiates, TCA, Haloperidol, AED, SSRI, NSAIDS Vincristine, cyclophosphamide • Chest: Pneumonia, TB, abscess • CNS: Meningitis, CVA, Tumour/mets • Post operative, NV, pain

  20. Case 2 JE • 67, Ca Prostate 2009 bone/liver mets -Previous TURP, RDx, Bicalutamide, stilbeosterol, zoladex -Neuroendocrine tumour-small cell -Etoposide and carboplatin and dex -Admitted to SCH prior to 1st cycle

  21. Clinical assessment • Nausea • Poor appetite • Dizziness • P=100, JVP not visible, grossly oedematous legs/scrotum • Meds: codanthramer, ondansetron, dex, domperidone

  22. Investigations

  23. Management

  24. Management of chronic severe ↓Na • Fluid restrictions -500ml IP -several days • Distal nephron inhibitors -Demeclocycline (tetracycline) -Nephrogenic DI-stops cAMP production -900 to1200mg per day, takes 3 days - SE: GI and photosensitive rash

  25. Chronic severe hyponatraemia • Urea -osmotic diuretic, increases free water excretion -oral 30g in orange juice -no need for fluid restriction • Vasopressin analogues VAPTANS -promote sustained aquaresis -Tolvaptan, selective V2 -check Na 8hrs after 1st dose then daily

  26. Mixed picture • Usually have other contributing factors -Vomiting -CCF -Liver failure -Renal impairment -Diuretics -Hyperglycaemia -need to consider other additional causes and manage

  27. Mild-moderate symptoms Na>125 • Acute: Tx cause and fluid restrict • Chronic: Tx cause and Vaptans • ASYMPTOMATIC NA>125 -Tx cause and fluid restrict

  28. Summary • Clinical Assessment: FLUID STATUS/ CAUSE/SEVERITY • Ix: UEs, Paired osm, urine Na, TFTs, (synacthen) LFTs, lipids and glucose • Tx: Acute vs. Chronic Severe vs. mild-moderate vs. asymptomatic • ? Mixed picture

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