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A case, many questions, and hopefully a few answers…<br />Chris NicksonEmergency Registrar, PMH19 August 2010<br />
The Case<br />10 year-old boy, previously well except for a history of enuresis <br />BIBA after a first episode generaliz...
In the ED<br />Afebrile<br />GCS 13 (E3 V4 M6) (fluctuating) for about 4 hours without improvement <br />PERL, no focal ne...
Lab results<br />UECNa 125K 4.1Urea 3.7    Cr 49<br />FBC normal<br />LFTs normal<br />VBGpH7.37 PCO2 42   HCO3 24    Cl 9...
Question -Is the sodium of 125 mmol/L likely to be significant?<br />
Symptoms of hyponatremia<br />UpToDate says typical symptoms of hyponatremia are:<125-130 mmol/L – nausea malaise<br /><11...
But…<br />Symptoms correlate poorly with degree of hyponatremia<br />May vary depending on:   starting sodium concentratio...
For instance…<br />A RAPID drop in Na of 140 to 125SYMPTOMS<br />A SLOW drop in Na of 130 to 115NO SYMPTOMS<br />
Question –How can we find out if the Na 125 mmol/L is important in this case?<br />
Fix it and see what happens!<br />3mL/kg of 3% saline over 30 minutes<br />Immediately following this infusion he was aler...
Question -Was it safe to give hypertonic sodium?<br />
What we fear…Fleming JD, Babu S. N Engl J Med 2008; 359:e29<br />
Weighing the risks<br />Most likely acute hyponatremia<br />The brain adapts<br />extrudes intracellular osmolytes to guar...
Weighing the risks<br />Give hypertonic saline to patients with significant symptoms of hyponatremiaregardless of how low ...
Question -How rapidly should hyponatremia be corrected?<br />
Rate of correction<br />Aim to increase sodium by1-1.5 mmol/h for 2 or 3 hours<br />a small rise can markedly improve symp...
More Lab tests…<br />Serum cortisol 1100 nM (60-420)TFTs normalOsmolality plasma 265 mmol/kg L (275-295)Spot urine sodium ...
Question -What do these results suggest?<br />
Syndrome of Inappropriate ADH Secretion<br />Low plasma osmolality<br />urine osmolality > plasma osmolality(usually >300-...
Question -How does ADH cause hyponatremia?<br />
ADH (aka vasopressin) action<br />promotes water reabsorption from the collecting ducts of the kidney <br />activates the ...
Question -But SIADH is not a diagnosis…What is the cause?<br />
Causes of SIADH<br />CNS disorders<br />Pulmonary disorders <br />Ectopic ADH secretion by a tumour –lung cancers (especia...
In fact, the patient has none of these!Question -What can mimic SIADH?<br />
SIADH mimics<br />Hereditary vasopressin receptor abnormalities (‘nephrogenic SIADH’)<br />Cerebral salt wasting<br />Exog...
The Answer…Remember the history of enuresis?<br />
They all lived happily ever after…<br />A nightly nasal spray of desmopressin was started 4 daysprior for nocturnal enures...
Question -Is hyponatremia a serious risk when treating enuresis with desmopressin?<br />
Robson WL et al. The comparative safety of oral versus intranasal desmopressin for the treatment of children with nocturna...
THE ENDhttp://lifeinthefastlane.com<br />
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A child, seizures and sodium

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A case of seizures in a child, with many questions and a few answers...

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A child, seizures and sodium

  1. 1. A case, many questions, and hopefully a few answers…<br />Chris NicksonEmergency Registrar, PMH19 August 2010<br />
  2. 2. The Case<br />10 year-old boy, previously well except for a history of enuresis <br />BIBA after a first episode generalized tonic-clonic convulsion<br />tired in the morning but still went to school sports competition<br />While getting ready to compete he collapsed and had a self-limiting seizure (5 min)<br />
  3. 3. In the ED<br />Afebrile<br />GCS 13 (E3 V4 M6) (fluctuating) for about 4 hours without improvement <br />PERL, no focal neurological deficits<br />vomited x5, but clinically euvolemic<br />CT head was normal<br />After the scan he had another self-limiting seizure (2 min)<br />
  4. 4. Lab results<br />UECNa 125K 4.1Urea 3.7    Cr 49<br />FBC normal<br />LFTs normal<br />VBGpH7.37 PCO2 42   HCO3 24    Cl 96    glc 7.2   lac 1.9<br />
  5. 5. Question -Is the sodium of 125 mmol/L likely to be significant?<br />
  6. 6. Symptoms of hyponatremia<br />UpToDate says typical symptoms of hyponatremia are:<125-130 mmol/L – nausea malaise<br /><115-120 mmol/L – headachelethargyobtundationseizurescomarespiratory arrest noncardiogenic pulmonary edema<br />
  7. 7. But…<br />Symptoms correlate poorly with degree of hyponatremia<br />May vary depending on: starting sodium concentration rate of decrease<br />
  8. 8. For instance…<br />A RAPID drop in Na of 140 to 125SYMPTOMS<br />A SLOW drop in Na of 130 to 115NO SYMPTOMS<br />
  9. 9. Question –How can we find out if the Na 125 mmol/L is important in this case?<br />
  10. 10. Fix it and see what happens!<br />3mL/kg of 3% saline over 30 minutes<br />Immediately following this infusion he was alert with a GCS 15 and had no further vomiting <br />His only complaint was a mild headache that improved after paracetamol<br />
  11. 11. Question -Was it safe to give hypertonic sodium?<br />
  12. 12. What we fear…Fleming JD, Babu S. N Engl J Med 2008; 359:e29<br />
  13. 13. Weighing the risks<br />Most likely acute hyponatremia<br />The brain adapts<br />extrudes intracellular osmolytes to guard against cerebral edema<br />Occurs over about 2 days<br />Risk of osmotic demyelination syndrome is minimal until adaptation occurs<br />
  14. 14. Weighing the risks<br />Give hypertonic saline to patients with significant symptoms of hyponatremiaregardless of how low the sodium is<br />AMS<br />Seizures<br />Coma<br />Noncardiogenic pulmonary edema <br />
  15. 15. Question -How rapidly should hyponatremia be corrected?<br />
  16. 16. Rate of correction<br />Aim to increase sodium by1-1.5 mmol/h for 2 or 3 hours<br />a small rise can markedly improve symptoms<br />Sodium should not be increased by more than:12mmol/Lover 24h18 mmol/L over 48hLower rates are advised for high risk patients<br />
  17. 17. More Lab tests…<br />Serum cortisol 1100 nM (60-420)TFTs normalOsmolality plasma 265 mmol/kg L (275-295)Spot urine sodium 209 mMSpot urine osmolality 681 mmol/kg (50-1200)<br />
  18. 18. Question -What do these results suggest?<br />
  19. 19. Syndrome of Inappropriate ADH Secretion<br />Low plasma osmolality<br />urine osmolality > plasma osmolality(usually >300-400 mosmol/kg)<br />Urine sodium usually >40 meq/L<br />Normal acid-base and potassium balance<br />Normal renal, liver, adrenal & thyroid function<br />Diuretics are not in use<br />improves with water restriction<br />
  20. 20. Question -How does ADH cause hyponatremia?<br />
  21. 21. ADH (aka vasopressin) action<br />promotes water reabsorption from the collecting ducts of the kidney <br />activates the vasopressin V2 receptor <br />aquaporin-2 water channels translocatefrom intracellular sites to the luminal membranes of the principal cells <br />end result is concentrated ‘water-poor’ urine and dilute ‘water-rich’ blood<br />
  22. 22. Question -But SIADH is not a diagnosis…What is the cause?<br />
  23. 23. Causes of SIADH<br />CNS disorders<br />Pulmonary disorders <br />Ectopic ADH secretion by a tumour –lung cancers (especially small cell lung cancers), others less common<br />Major surgery <br />Many drugs<br />
  24. 24. In fact, the patient has none of these!Question -What can mimic SIADH?<br />
  25. 25. SIADH mimics<br />Hereditary vasopressin receptor abnormalities (‘nephrogenic SIADH’)<br />Cerebral salt wasting<br />Exogenously administered vasopressin agonists <br />Vasopressin<br />Desmopressin<br />Oxytocin<br />
  26. 26. The Answer…Remember the history of enuresis?<br />
  27. 27. They all lived happily ever after…<br />A nightly nasal spray of desmopressin was started 4 daysprior for nocturnal enuresis<br />His parents encouraged him to ‘drink lots of water’ before competing<br />Over the next 12-24 hours he had a large diuresis, his laboratory values all normalized and he remained well<br />
  28. 28. Question -Is hyponatremia a serious risk when treating enuresis with desmopressin?<br />
  29. 29. Robson WL et al. The comparative safety of oral versus intranasal desmopressin for the treatment of children with nocturnal enuresis.J Urol. 2007 Jul;178(1):24-30.<br />Hyponatremia resulting from treatment of enuresis with desmopressin<br />No reports in 21 clinical trials<br />48 case reports (all nasal route)<br />Post-marketing safety data: 145 nasal, 6 oral cases<br />Risk factors<br />High fluid intake, age <6 years, high dose, other medications (e.g. anticholinergics)<br />
  30. 30. THE ENDhttp://lifeinthefastlane.com<br />

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