1. Sodium
Disorders of sodium concentration reflect abnormalities in water homeostasis
Serum sodium concentration does not provide any information about sodium content i.e. volume status It is only the ratio of sodium to extracellular fluid in which it is contained

4. Hyponatremia
Hx: duration of hyponatremia, presence of symptoms,( change in mental status, lethargy, seizure, coma ) potential causes
PE: asses volume status, skin turgor, BP/orthostasis, pulmonary edema, peripheral edema

8. Lab Evaluation

9. Dilutional Hyponatremia

10. Low volume

11. Dilutional Hyponatremia

14. SIADH
Inappropriate ADH response in a patient with hyponatremia. Urine is less than maximally dilute in the presence of relative euvolemia
Tx: free water restriction, loop diuretics, high protein and salt intake. Occasionally demeclocycline

18. Symptomatic Hyponatremia
CNS symptoms often respond to modest increases in sodium (<5%)
Initial rate 1-2 mmol/L until symptoms resolve
Then 8 mmol total in first 24 hrs.
Then 10 mmol in next 24 hrs.

19. Severity of Symptoms
Moderately severe: nausea without vomiting, confusion, headache,
Severe: nausea with vomiting, cardio- respiratory distress, abnormal and deep somnolence, seizures, coma Glasgow < 8

20. Severe Symptoms – 1st hour
150 ml of 3% saline over 20 min
Check serum sodium after 20 min while starting second 150 ml bolus of 3%
Repeat up to 2 more times until a rise of 5 mmol/l is acheived

21. Severe Symptoms – f/u care
f/u care if improvement in symptoms after 5 mmol/L increase is achieved
Stop hypertonic saline
Start a diagnosis specific treatment
Limit rise in sodium to no more than 10 mmol/L in first 24 hrs, and no more than 8 mmol/L in subsequent days till reach 130
Check Na every 6 and 12 hrs and then daily

22. Severs symtoms – f/u care
f/u care if no improvement in symptoms after 5 mmol/L rise in first hour of treatment
Continue 3% saline IV aiming for an increase in 1 mmol/h rise in sodium
Stop IV if symptoms improve, a rise in sodium of 10 mmol/L occurs, or sodium reaches 130
check sodium q4hrs during hypertonic drip

23. Rate of 3%– Adrogue-Madias
To achieve 1 mmol/L per hr increase
Change Na = infusate Na – serum Na/TBW + 1
Include any potassium if in the infusate, i.e. infusate Na + infusate K
TBW = .6 X body weight in men
= .5 X body weight in women

24. Correction Example Chg in Na/L of fluid=IV Na – Pna/TBW+1
3%saline = 513 mmol/L
Vol IV = desired change/expected chg 1L
Rate infusion = Vol/time

25. Correction Example 70 kg man obtunded Na = 110 Goal inc Na by 4 mmol/L
513 – 110 / 42+1 = 9.37 with 1L of 3%
Vol of 3% = 4/9.37 = 400cc
Rate = 400cc / 2hrs = 200 cc/hr of 3%

26. Moderate Symptoms 150 cc of 3% saline over 20 min
Aim for a 5 mmol/L increase in Na over 24 hours
Limit rise in sodium to no more than 10 mmol/L in first 24 hrs, and no more than 8 mmol/L in subsequent days till reach 130
Check Na after 1, 6 and 12 hrs and then daily

27. Acute hyponatraemia w/o symptoms
Cause specific treatment
A single dose of 150 ml of 3% saline over 20 min, only if the acute decease in serrum sodium exceeds 10 mmol/L

28. Chronic Hyponatremia w/o symptoms
Mild hyponatremia 130 – 135 no treatment soley to increase sodium
Moderate (125 – 129) and severe (< 125) avoid an increase of more than 10 mmol/L in first 24 hrs and no more than 8 mmol/L each subsequent 24 hrs till reach 130
Check sodium every 6 hrs till sodium has stabalized

29. Expanded extracellular volume
No treatment with sole aim of increasing sodium in mild and moderate cases
Fluid restriction to prevent further fluid overload

30. SIADH
In moderate and profound cases – fluid restriction is first line tx
2 choices for second line therapy
a) Combination of low dose loop diuretic and oral salt tablets
b) increase solute load with 0.25 – 0.5 g/d of urea

31. Reduced circulating volume
0.9 % saline infusion at 0.5 – 1.0 ml/kg per H
In case of hemodynamic instability the need for rapid fluid resuscitation overrides the risk of an overly rapid increase in serum sodium concentration

32. Overcorrection
Prompt intervention for sodium rise > 10 mmol/L for the first day and 8 mmol/L for following days
Start an infusion of 10 ml/kg of free water over 1 hour
Consider IV desmporessin 2 micrograms, not more frequently than every 8 hours

33. Correction
There is no substitute for frequent monitoring of the sodium response

34. Hypernatremia
All forms of hypernatremia are associated with hyperosmolarity
Volume status cannot be inferred from the presence of hypernatremia

35. Symptoms
CNS invovlement – lethargy, irritability, weakness, confusion – usually occur with sodium greater than 160

36. Etiology

37. Low ECF Volume

38. Correction of Hypernatremia
Rate of correction .5 mmol/L/hr
Severe Vol depletion or hemodynamic instability merits tx with .9NS
Lesser degrees of volume depletion can be treated with ½ or ¼ normal saline
Once volume is corrected can use D5W

39. Correction Example 70 kg female Na 170 stable vitals
Goal 12 mmol/L over 24 hrs with D5W
70kg X .4 = 28L of body water
Chg Na 1L D5W = 170-0/28+1 = 5.86 mmol/L
Vol of D5W = 12/5.86 = 2.04L
Rate = 2.04L/24hrs = 80 cc/hr
No accounting for ongoing losses

40. Potassium
Hypo and hyper kalemia results from alterations in intake, cellular shifts or alterations in elimination

41. Hyperkalemia Etiology
Transcellular Shift
Exercise, hyperchloremic metabolic acidosis, Insulin deficiency, hypertonicity, alpha adrenergic stimulation, tissue breakdown/ischemia (rhabdo, brain, gi)

42. etiology Decreased renal excretion – CRF, Hypoaldo
(meds i.e. ACE/ARB, NSAIDs,
heparin. Type 4 RTA

43. Etiology Pseudohyperkalemia
ischemic/traumatic blood draw,increased wbc/plts (100, ,000)

44. Hyperkalemia
Sx: neuromuscular weakness and cardiac conduction problems
Level of K at which problems occur is very variable between patients

45. Etiology Increased Total Body K increased intake (rare as sole cause)
decreased renal excretion
Spurious – Thrombocytosis, Leukocytosis, ischemic blood draw

46. Diagnosis Normal to High 24 hr urinary K >40 meq/d
relative increase in K intake
Low 24 hr urinary K < 20 – 40 meq/d
Decreased renal K excretion
GFR < 20 ml/min
endogenous K load
drugs that impair K excertion

47. Diagnosis
Low 24 hr urine K – GFR > 20 ml/min decrease mineralcorticoid production/action
Action – pseudohypoaldo type 1 or 2
Acquired ARB, aldactone,
amiloride, sickle cell,
obstruction
Production - Hypoaldo, ACE, Heparin,

48. Diagnosis Decreased distal nephron sodium delivery
Heart failure, cirrhosis, volume
depletion

49. hypokalemia Mild is asymptomatic (3.0 – 3.5)
Sever muscle weakness,pain can cause rhabdo prominent U waves diminished or inverted T waves ST depression leads to v-fib

50. Hypokalemia - Etiology
Shift
Alkalemia, insulin, refeeding, thyrotoxicosis, Hypokalemic perodic paralysis, Barium
Decreased Total Body K
Decreased intake
Increased Loss GI or Renal
Spurious – Extreme leukocytosis

51. Diagnosis Low 24 hr K loss < 20 mEq/d Extrarenal
metabolic acidosis – GI loss Diarrhea
normal pH – decreased intake
metabolic alkalosis – GI Loss Vomiting

52. Diagnosis High 24 hr urine K >20 mEq/d Metabolic alkalosis
low Urine Cl vomiting/diuretics
High Urine Cl – Hpertension
Nl Aldo – Cushing/Liddle/Appatent Mineralcorticoid excess
High Aldo – 1 hyperaldo/GRA
- normal/low BP – Bartter/Gitelman

53. Etiology Met Acidosis Proximal or distal RTA Variable pH
Magnesium depletion
Anionic drugs