1. HYPONATREMIA & HYPERNATREMIA
by:M.S.Mojtabavi

2. Hypernatremia Due to: Plasma Na+ > 145 mEq / L
Due to ↑ Na + or ↓ water
Due to:
Excess Na intake (hypertonic IV solution)
Excess Na retention (oversecretion of aldosterone)
Loss of pure water
Long term sweating with chronic fever
Respiratory infection Diabetes (mellitus or insipidus) – polyuria
Insufficient intake of water (hypodipsia)

4. Clinical manifestations of Hypernatremia
Thirst
Lethargy
Irritability
Seizures
Fever
Oliguria

5. Diagnostic Strategies
In addition to routine serum chemistries, serum osmolarity and
urine sodium concentration and osmolality should be obtained.
The degree of hypernatremia almost always equals the total body
water deficit in adults.
TBW deficit = TBW×(serum Na+ /140)−1

7. The rate of correction in hypernatremia is extremely important to minimize morbidity and mortality. In adult patients who have had hypernatremia during a short time as a result of sodium loading, “rapid correction” at 1 to 2 mEq/hr lowering of serum sodium appears relatively safe.
However, most adult patients have hypernatremia during days to weeks. In this group of patients, serum sodium concentration should be slowly corrected at no more than 0.5 mEq/hr or 10 to 12 mEq/day.

8. Normal saline can typically be started for volume replacement until the patient is hemodynamically stable and then changed to half-normal saline at 100 mL/hr once vital signs have normalized.
The treatment of central diabetes insipidus with desmopressin (DDAVP) is an effective means of improving polyuria and hypernatremia; initial doses in the acute setting range from 1 to 2 μg.

9. So let’s do a sample calculation:
60 kg woman with 168 mEq/L
Water deficit = 0.4 x 60 ([168/140]-1) = 4.8 L
sodium should not be lowered by more than 12 mEq/L in 24 hours
Overcorrection can lead to cerebral edema which can lead to encephalopathy, seizures or death
The 4.8 L which will lower the sodium level by 28 should be given over hours, or at a rate of mL/hr
Typical fluids given in form of D5 water

11. HYPONATREMIA Definition:
Commonly defined as a serum sodium concentration 135 meq/L
The most common causes of severe hyponatremia in adults are therapy with thiazides, the postoperative state including transurethral prostatectomy, the syndrome of inappropriate secretion of antidiuretic hormone (SIADH), polydipsia in psychiatric patients,

12. Most patients presenting to the emergency department (ED) with hyponatremia are asymptomatic and do not require emergent therapy.
Symptoms range from headache, nausea, and vomiting to confusion, seizures, and coma.

13. two groups of hyponatremic patients require treatment with either normal saline or hypertonic saline:
(1asymptomatic hyponatremia with a sodium level of 110 mEq/L or less
(2acute symptomatic hyponatremia with a sodium level below 120 mEq/L.

14. HYPONATREMIA Types Hypovolemic hyponatremia Euvolemic hyponatremia
Hypervolemic hyponatremia
Pseudohyponatremia

16. Diagnostic Strategies:
urinary sodium or urinary chloride level is useful:
Patients with hypovolemic hyponatremia due to nonrenal causes, urinary sodium or chloride level (<20 mEq/L)
Patients with hypovolemic hyponatremia due to renal causes , urine sodium and chloride levels above 20 mEq/L
Patients with euvolemic hyponatremia typically have a urinary sodium greater than 20 mEq/L
Patients with hypervolemic hyponatremia secondary to CHF or cirrhosis have urine sodium levels of less than 20 mEq/L
renal causes of hypervolemic hyponatremia or with SIADH have sodium levels in excess of 20 mEq/L

17. Diagnostic Strategies
Plasma osmolality ,Urine osmolality ,Urine sodium concentration ,Uric acid level,FeNa
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
Urine Sodium
>20 mEq/L
SIADH, diuretics
<20 mEq/L
Uric Acid Level
< 4 mg/dl consider SIADH
FeNa
Help to determine pre-renal from renal causes

18. 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
Nonspecific signs of hyponatremia include anorexia, nausea,vomiting, and generalized weakness.
Acutely hyponatremic patients whose sodium level drops below 120 mEq/L during 24 to 48 hours may present with severe neurologic findings, including confusion, seizures, cerebral edema, coma, and brainstem herniation.

19. Management:
For relatively asymptomatic patients with sodium values of 115 to 135 mEq/ L, free water restriction is typically the single most important treatment.
In more severe cases when the sodium value is 120 mEq/L or less and the patient has alterations in mental status, has focal findings, or is seizing, hypertonic saline is indicated.

20. Treatment calculate the total body water
total body water (TBW) = 0.6 × body weight
How much sodium does the patient need?
Sodium deficit = Total body water x (desired Na – actual Na)
critically ill hyponatremic patients with seizures, focal findings, or coma receive 100 mL of 3% hypertonic saline during 10 minutes. If a second bolus is required, an additional 100 mL of the 3% solution (513 mEq/L of sodium) may be administered during the next 50 minutes.
Goals for correction:
1.5 to 2 mEq/L per hour for first 3-4 hours until symptoms resolve
Increase by no more than 10 mEq/L in first 24 hrs
Increase by no more than 18 mEq/L in first 48 hrs

21. Hypovolemic Hyponatremia:
the normal saline is started at 500 to 1000 mL/hr until the blood pressure is stable.
then slowed to 200 mL/hr with frequent sodium checks.
rise only by an average of 0.5 mEq/hr or 10 to 12 mEq/day.

22. Hypervolemic Hyponatremia:
Restriction of fluid and sodium is the preferred treatment.
loop diuretics
Hemodialysi
albumin

23. Euvolemic Hyponatremia:
As the hypo-osmolality in SIADH, restriction of free oral water intake is the first recommendation.
antineoplastic therapy
hypertonic saline
Demeclocycline and lithium
Vaptans
hemodialysis

24. an example: 60 kg woman with sodium level of 116
Sodium needed = 0.5 x 60 x ( ) = 240
The patient needs 240 mEq in next 24 hours
That averages to 10 mEq per hour or 20 mL of hypertonic saline per hour
However, this will only raise the serum sodium by 0.33 per hour therefore, increasing the rate 60 mL to 90 mL will produce the desired rate of serum sodium increase of 1.0 to 1.5 mEq per hour until symptoms resolve

25. What if the sodium increases too fast?
The dreaded complication of increasing sodium too fast is Central Pontine Myelinolysis which is a form of osmotic demyelination
Symptoms generally occur 2-6 days after elevation of sodium and usually either irreversible or only partially reversible
Symptoms include: dysarthria, dysphagia, paraparesis, quadriparesis, lethargy, coma or even seizures