3. • Definition:
– Commonly defined as a serum sodium concentration
135 meq/L
– Hyponatremia represents a relative excess of water in
relation to sodium.
4. : Epidemiology
ocw.jhsph.edu
Frequency
Hyponatremia is the most common electrolyte
disorder
incidence of approximately 1%
prevalence of approximately 2.5%
surgical ward, approximately 4.4%
of patients treated in the intensive care unit 30%
5. . Epidemiology Cont
Mortality/Morbidity ›
Acute hyponatremia (developing over 48 h or
less) are subject to more severe degrees of
cerebral edema
sodium level is less than 105 mEq/L, the mortality is
over 50%
Chronic hyponatremia (developing over more
than 48 h) experience milder degrees of
cerebral edema
Brainstem herniation has not been observed in
patients with chronic hyponatremia
6. . Epidemiology Cont
Age ›
Infants
fed tap water in an effort to treat symptoms of
gastroenteritis
Infants fed dilute formula in attempt to ration
Elderly patients with diminished sense of thirst,
especially when physical infirmity limits
independent access to food and drink
7. Physiology
Serum sodium concentration ›
:regulation
stimulation of thirst
secretion of ADH
feedback mechanisms of the
renin-angiotensin-aldosterone
system
renal handling of filtered sodium
8. . Physiology Cont
Stimulation of thirst ›
Osmolality increases
Main driving force
Only requires an increase of 2% - 3%
Blood volume or pressure is reduced
Requires a decrease of 10% - 15%
Thirst center is located in the anteriolateral
center of the hypothalamus
Respond to NaCL and angiotensin II
12. . Physiology Cont
extracellular-fluid and intracellular-fluid ›
compartments make up 40 percent and 60
percent of total body water
renal handling of water is sufficient to ›
excrete as much as 15-20 L of free water per
day
sodium is the predominant osmole in the ›
extracellular fluid (ECF) compartment and
serum
13. Pathophysiology
hyponatremia can only occur when some ›
condition impairs normal free water
excretion
:acute drop in the serum osmolality ›
neuronal cell swelling occurs due to the water
shift from the extracellular space to the
intracellular space
Swelling of the brain cells elicits 2 responses for
:osmoregulation, as follows
It inhibits ADH secretion and hypothalamic thirst
center
immediate cellular adaptation
15. develops as sodium and free
water are lost and/or
replaced by inappropriately
hypotonic fluids
Sodium can be lost through
renal or non-renal routes
www.grouptrails.com/.../0-Beat-Dehydration.jpg
16. Nonrenal loss
GI losses ›
Vomiting, Diarrhea, fistulas, pancreatitis
Excessive sweating ›
Third spacing of fluids ›
ascites, peritonitis, pancreatitis, and burns
Cerebral salt-wasting syndrome ›
traumatic brain injury, aneurysmal
subarachnoid hemorrhage, and intracranial
surgery
Must distinguish from SIADH
www.jupiterimages.com
17. Renal Loss ›
Acute or chronic renal insufficiency
Diuretics
www.ct-angiogram.com/images/renalCTangiogram2.jpg
18.
19. Normal sodium stores and a total body
excess of free water
Psychogenic polydipsia, often in psychiatric
patients
Administration of hypotonic intravenous or
irrigation fluids in the immediate postoperative
period
20. administration of hypotonic maintenance ›
intravenous fluids
Infants who may have been given ›
inappropriate amounts of free water
bowel preparation before colonoscopy or ›
colorectal surgery
22. Total body sodium increases, and TBW
. increases to a greater extent
Can be renal or non-renal
acute or chronic renal failure
dysfunctional kidneys are unable to excrete the
ingested sodium load
cirrhosis, congestive heart failure, or nephrotic
syndrome
23. Water shifts from the intracellular to the ›
extracellular compartment, with a resultant
dilution of sodium. The TBW and total body
. sodium are unchanged
This condition occurs with hyperglycemia
Administration of mannitol
24. Pseudohyponatremia
The aqueous phase is diluted by excessive ›
proteins or lipids. The TBW and total body
. sodium are unchanged
hypertriglyceridemia
multiple myeloma
25. Clinical Manifestations
most patients with a serum sodium
concentration exceeding 125 mEq/L are
asymptomatic
Patients with acutely developing
hyponatremia are typically symptomatic at
a level of approximately 120 mEq/L
Most abnormal findings on physical
examination are characteristically
neurologic in origin
patients may exhibit signs of hypovolemia or
hypervolemia
›
›
›
›
26. Diagnosis
CT head, EKG, CXR if symptomatic
Repeat Na level
Correct for hyperglycemia
Laboratory tests provide important initial
information in the differential diagnosis of
hyponatremia
Plasma osmolality
Urine osmolality
Urine sodium concentration
Uric acid level
FeNa
›
›
›
›
27. .Laboratory tests Cont
Plasma osmolality ›
normally ranges from 275 to 290 mosmol/kg
: If >290 mosmol/kg
Hyperglycemia or administration of mannitol
:If 275 – 290 mosmol/kg
hyperlipidemia or hyperproteinemia
:If <275 mosmol/kg
Eval volume status
31. Treatment
four issues must be addressed ›
Asymptomatic vs. symptomatic
(acute (within 48 hours
(chronic (>48 hours
Volume status
1st step is to calculate the total body water ›
total body water (TBW) = 0.6 × body weight
32. .
Treatment Cont
•
next decide what our desired correction rate ›
should be
Symptomatic ›
immediate increase in serum Na level by 8 to 10
meq/L in 4 to 6 hours with hypertonic saline is
recommended
acute hyponatremia
›
more rapid correction may be possible
to 10 meq/L in 4 to 8 hours 8
chronic hyponatremia
slower rates of correction
meq/L in 24 hours 12
›
33. Symptomatic or Acute ›
!!!Treatment Cont. - Here comes the Math
estimate SNa change on the basis of the amount of
Na in the infusate
(ΔSNa = {[Na + K]inf − SNa} ÷ (TBW + 1
ΔSNa is a change in SNa
Na + K]inf is infusate Na and K concentration in 1 liter of]
solution
!!!!!!!!!!!!!!!!!!OH MY GOD, what did he just say
34. IV Fluids
:One liter of Lactated Ringer's Solution contains ›
mEq of sodium ion = 130 mmol/L 130
mEq of chloride ion = 109 mmol/L 109
mEq of lactate = 28 mmol/L 28
mEq of potassium ion = 4 mmol/L 4
mEq of calcium ion = 1.5 mmol/L 3
:One liter of Normal Saline contains ›
mEq/L of Na+ and Cl 154
−
:One liter of 3% saline contains ›
mEq/L of Na+ and Cl 514
−
35. :Example
a 60 kg women with a plasma sodium of 110 ›
meq/L
:Formula ›
(ΔSNa = {[Na + K]inf − SNa} ÷ (TBW + 1
?What is the TBW ›
How high will 1 liter of normal saline raise the ›
? plasma sodium
:Answer
TBW is 30 L ›
Serum sodium will increase by approximately ›
1.4 meq/L for a total SNa of 111.4 meq/L
36. :Example
a 90 kg man with a plasma sodium of 110 ›
meq/L
:Formula ›
(ΔSNa = {[Na + K]inf − SNa} ÷ (TBW + 1
?What is the TBW ›
How high will 1 liter of 3% saline raise the ›
? plasma sodium
:Answer
TBW is 54 L ›
Serum sodium will increase by approximately ›
7.3 meq/L for a total SNa of 117.3 meq/L
37. Asymptomatic or Chronic
SIADH ›
response to isotonic saline is different in the
SIADH
In hypovolemia both the sodium and water
are retained
sodium handling is intact in SIADH
administered sodium will be excreted in the
urine, while some of the water may be
retained
possible worsening the hyponatremia
38. Asymptomatic or Chronic
SIADH ›
Water restriction
liter/day 0.5-1
Salt tablets
Demeclocycline
Inhibits the effects of ADH
Onset of action may require up to one week
39. :Example
y/o male with weakness and head ache 85
SNa is 118 mEq/L
Plasma osmolality is 254 mosmol/kg
Urine osmolality is 130 mosmol/kg
Urine sodium >20 mEq/L
Uric acid is 3mg/dl
What type of hyponatremia does this
?patient have
What additional labs/studies would you
?want
–
–
–
–
–
–
•
•
41. :Example
•
y/o female at 75 Kg with N/V/D for 4 days 63 –
SNa is 108 mEq/L –
She has had one seizure in the ambulance –
•
Plasma osmolality is 251 mosmol/kg
•
Urine osmolality is 47 mosmol/kg
Uric acid is 6mg/dl •
hollywoodphony.files.wordpress.com
What type of hyponatremia does this •
?patient have
What additional labs/studies would •
?you want
42. ?How will you Tx her
Calculate the total body water
x weight = 37.5 L 0.5
›
?What rate of correction do you want
to 10 mEq/L in 6 to 8 hours 8
?What fluid will you use
Saline 3%
›
›
How will you calculate the amount of sodium ›
?to give her
(ΔSNa = {[Na + K]inf − SNa} ÷ (TBW + 1
How will her sodium increase after 1 liter of 3% ›
?saline
By 10.8 mEq/L to 118.8 mEq/L
43. ?What other medication will she need
Lasix and a foley ›
Her sodium increases to 118.8 mEq/L over
the next 8-10 hours. How will you continue to
?correct her hyponatremia
(ΔSNa = {[Na + K]inf − SNa} ÷ (TBW + 1 ›
ΔSNa = 154mEq/L – 118.8mEq/L ÷ 38.5L = 0.9 ›
mEq/L
So 2 liters of normal saline over the next 14
hours
44. The syndrome of inappropriate antidiuretic hormone secretion or
SIADH (other names: Schwartz-Bartter syndrome, SIAD—syndrome of
immoderate antidiuresis) is characterized by excessive release
of antidiuretic hormone from the posterior pituitary gland or another
source. The result is often dilutional hyponatremia in which Athe
sodium remains normal but total body fluid increases. It was originally
described in people with small-cell carcinoma of the lung, but it
can be caused by a number of underlying medical conditions. The
treatment may consist of fluid intake restriction, various medicines,
And management of the underlying cause.
