Hyponatremia

Hyponatremia - approach and management

1. HYPONATREMIA DR VANDANA G HARI MBBS DNB RESIDENT DEPT OF HEMATOLOGY MADRAS MEDICAL COLLEGE

2. HYPONATREMIA Hyponatraemia, defined as a serum sodium concentration <135 mmol/L. The most common disorder of body fluid and electrolyte balance encountered in clinical practice. 15–20 % of emergency admissions to hospital and occurs in up to 20 % of critically ill patients.

3. DEFINITIONS Mild hyponatraemia 130-135 mmol/L as measured by ion specific electrode. Moderate’ hyponatraemia 125-129 mmol/L as measured by ion specific electrode. Profound’ hyponatraemia <125 mmol/L as measured by ion specific electrode.

4. Acute – Less than 48 hours Chronic – More than 48 hours Unknown consider as chronic

5. Moderately severe Nausea without vomiting Confusion Headache

6. Severe Vomiting Cardio-respiratory distress Abnormal and deep somnolence Seizures Coma (Glasgow Coma Scale less than 8)

7. Case History -1 A 64 year-old man with a past medical history of hypertension, depression, and IgG lambda multiple myeloma presents to the hospital to initiate chemotherapy. C/o tiredness

8. Physical examination Pallor + No edema PR-90/min BP 140/70mmhg Systems – NAD

9. Labs Hb 9.5g/dl TC 5600 Platelets – 200000/ cumm Biochemistry Creatinine – 0.9 Urea 24 LFT Bil 1 , AST – 24 ALT 26 ALP 100 Total Protein – 10 .6 Albumin 3.2

10. Sodium 128 Chloride 106 Potassium 4.2 Glucose 108 mg / dl pT 10/0.8 aptt - 28

11. ????? Moderate hyponatremia- Asymptomatic

12. Step 1 of evaluation Calculate serum osmolality Formula – 2XSodium mEq /L+ Glucose in mg/dl/ 18+BUN mg/dl /2.8 Normal 275- 295 mOsm /kg

13. Further evaluation Serum osmolality : This test can help us get a better sense of our patient’s tonicity in the setting of hyponatremia. The serum osmolality is 285 mOsm /kg. (normal range: 275 – 295 mOsm /kg)

14. So diagnosis……… Pseudohyponatremia---- Low Sodium with increased or normal Serum osmolality

15. Blood Urea Nitrogen – Urea / 2 ( nitrogen contributes approx 46 % of molecular weight of Urea CO (NH2)2

16. Pseudohyponatremia

17. 1.Translocational Pseudohyponatremia

18. Blood with glucose / mannitol High osmolality cell w w w

19. 2. Hyponatremia with normal osmolality Estimation with Flame spectrometry in serum with high lipids and proteins Present day – Ion sensitive electrode method- Accurate

20. Case 2 A 38-year-old male in excellent health suffered a fall from a tree causing a right leg fracture and blunt trauma to the head with concussion but no other signs of head injury. The patient was discharged several days after surgery for repair of his leg fracture. On 6 th day after his discharge he presented to ER severely ill with nausea, vomiting, headache, and seizures.

21. O/E patient drowsy GCS 10 / 15 No edema Bp 120/70 PR 98 /min Afebrile Systems- CNS drowsy moves all 4 limbs Rest Normal

22. Seizures ? Cause…. in post ictal confusion

23. A repeat CT brain- Normal CBC/RFT – normal Serum Sodium – 100meq/ L Glucose 100 BUN- 24mg/dl

24. Diagnosis – Hyponatremia induced seizure

25. What next ??? Calculate serum osmolality 2X 100 + 100/18+ 24/ 2.8= 214 mosm / kg Low serum osmolality ---- True hyponatremia Formula – 2XSodium mEq /L+ Glucose in mg/dl/ 18+BUN mg/dl /2.8 (275-295)

26. Step 2 – Volume status of the patient Euvolemic – may be in hypovolemia post correction Hypovolemic Hypervolemic- In case of edema CCF/CKD/CLD/Nephrotic syndrome

27. Mechanism of hypervolemic hyponatremia Sodium water reabsorption Water more than sodium Dilutional Hyponatremia

28. How to treat hypervolemic hyponatremia?? Treatment – Loop diuretics – Furosemide .

29. What if the patient is hypovolemic ???

30. Hypovolemic hyponatremia LOSS OF WATER

31. Euvolemic hyponatremia Hypocortisolism Hypothroidism SIADH

32. Evaluation of euvolemic hyponatremia 1. Serum Osmolality – To assess the tonicity 2. Urine Osmolality- To assess activity of ADH . High ADH activity – more water reabsorbed –Concentrated urine – Increased urine osmolality (>100)

33. 3.Urine Sodium– A measure of effective circulating volume Low effective circulating volume – Renin angiotensin aldosterone activation ---More sodium reabsorbed – Less Urine sodium (<30 mmol/L) 4.TSH 5. Serum Cortisol levels

34. SIADH Effective serum osmolality <275 mOsm /kg Urine osmolality>100 mOsm /kg Clinical euvolemia Urine sodium concentration>30 mmol/L Absence of adrenal, thyroid, pituitary or renal insufficiency No recent use of diuretic agents

35. 22 year old with gastroenteritis Dehydrated with sodium 118 Body weight 60 kg Asymptomatic 1 L NS – 154 meq /L 1L 3%saline 513

36. How much ??

37. Change in sodium =154- 118/ TBW+ 1 TBW =60% of weight =60%x 60kg = 36 kg There fore 154-118 36+ 1 = 36/37= 1meq/L 22 year old with gastroenteritis Dehydrated with sodium 118 Body weight 60 kg Total BW 60% of 60 kg= 36 kg

38. 1L of normal saline will produce 1 meq rise in sodium Daily sodium correction – maximum 8mEq/L Recommended 5mEq/day – 5 l of NS

39. How to treat ??? Treatment of hyponatremia with severe symptoms

40. Management of acute symptomatic hyponatremia Fluid of choice – 3% Saline 1L of 3% saline – 513 meq /L Recommendation 100ml 3%HTS x 3times each infusion over 10 – 15 minutes

41. 38 year old 60 kg with sodium 100Meq/L 1L 3% saline = 513 mEq TBW 60% of weight =36 kg Ie 513-100/ 37=413/37=11.16 1L 3%saline will increase his sodium by 11.16 300ml will increase by 3.7 mEq /L

42. Patient improves Continue normal saline infusion at very low volume Evaluate for the cause and treat the cause Check the sodium every 6 hours

43. No improvement of symptoms after a 5 mmol/L increase in serum sodium concentration in the first hour intravenous infusion of 3 % hypertonic saline target sodium rise 1 mEq /L/hour to maximum 8 meq /L/day. Check sodium every 4 hours while on 3% saline infusion

44. Treatment of chronic hyponatremia If asymptomatic –brain shrinks in size to accommodate the edema 3% saline in chronic asymptomatic case or correction more than 8 mEq /L/day--- Further shrinking of brain – Further water from brain to CSF ---Osmotic demyelination – Clinical symptoms-Dysarthria/ dysphagia/ paraparesis/ lethargy/confusion / coma

45. Treatment of asymptomatic chronic hyponatremia 1. Fluid restriction 2. Oral salts 3.Vaptans- V2 receptor antagonist—(v2- mediate anti diurectic response ) Example Tolvaptan 15mg once daily CI- CLD .AE : hepatotoxic May be used in hypervolemic also

46. Thank You

47. Reference Clinical practice guideline on diagnosis and treatment of hyponatraemia Intensive Care Med (2014) 40:320–331 DOI 10.1007/s00134-014-3210-2 Uptodate Harrison 20 th edition