Hyper/hyponatremia

Question 1

Distribution of body solids and fluids?

In both men and women

Answer 1

1. solids - 45% females and 40% males
2. fluids - 55% female and 60% males
   > 2/3 intercellular fluid
   > 1/3 extracellular fluid
   - 80% interstitial fluid
   - 20% plasma

Question 2

Normal plasma ranges of electrolytes?

Answer 2

1. Mg - 1.6-2.6 mg/dl
2. PO4 - 1.9-4.3 mg/dl
3. Ca2+ - 2.0-2.5 mmol/L
4. K+ - 3.5-5.5 mmol/L
5. Cl- - 102-116 mmol/L
6. Na+ - 135-145 mmol/L

Question 3

Function of sodium?

Answer 3

1. to conduct nerve impulses
2. contract and relax muscles
3. maintain the proper balance of water and minerals

Question 4

Hypernatremia?

Answer 4

Hypernatremia is characterized by a serum sodium level above 145 mEq/L (SI, 145 mmol/L) or ULN

Question 5

Causes of hypernatremia?

Answer 5

1. the body has an excess of sodium relative to water
2. Water deficit or excess sodium intake can lead to hypernatremia, making body fluids more hypertonic

Question 6

Release of Antidiuretic hormone (ADH)?

Answer 6

• released from hypothalamus and stored in posterior pituitary
• Released with high plasma osmolality and hypovolemia

Question 7

Function of ADH hormone?

Answer 7

• Increases water permeability in distal tubule and renal collecting ducts
• results in water retention thus reducing the concentration of solutes such as sodium

Question 8

When is ADH pathologically released?

Answer 8

Syndrome of inappropriate ADH secretion (SIADH)
e.g. pain, tumour, trauma

Question 9

Release of Aldosterone?

Answer 9

from adrenal cortex in the adrenal gland

Question 10

Function of aldosterone?

Answer 10

acts on the distal tubules and collecting ducts of the kidney to cause the:
1. conservation of sodium
2. secretion of potassium
3. increased water retention
4. increased blood pressure

Question 11

Causes of hypernatraemia - water deficit?

Answer 11

1. fever
2. heat stroke
3. pulmonary infections
4. extensive burns
5. severe diarrhea
6. hypersomolar hyperglycemic nonketotic syndrome
7. urea diuresis
8. diabetes insipidus

Question 12

Causes of hypernatremia - excess sodium?

Answer 12

1. overconsumption of dietary sodium
2. use of certain drugs
3. near drowning in salt water
4. Cushings syndrome
5. hyperaldosteronism

Question 13

Drug causes of hypernatremia?

Answer 13

1. antacids
2. NaCl IV

Question 14

Diagnostic tests for hypernatrmia?

Answer 14

1. Measure serum osmolality (formula)
   - Serum Osmolality above 300m/Osm/kg
   - Serum sodium level above 145 meq/L or ULN
2. Urine specific gravity above 1.030 (or less than 1.005 in DI)

Question 15

Calculating serum osmolality?

Answer 15

2(Na+) + Glucose (mg/dl/18) + BUN (mg/dl/2.8)

Question 16

Rapid correction of severe hypernatremia can cause?

Answer 16

cerebral edema

Question 17

Hypernatremia signs and symptoms?

you are FRIED

Answer 17

1. Fever (low grade), flushed skin
2. Restless (irritable)
3. Increased fluid retention and increased BP
4. Edema (peripheral and pitting)
5. Decreased urinary output, dry mouth

Question 18

Hypernatremia sign and symptoms?

SALT

Answer 18

1. Skin flushed
2. Agitation
3. Low-grade fever
4. Thirst

Question 19

Hyponatremia?

Answer 19

Hyponatremia is characterized by a serum sodium level below 135 mEq/L (SI, 135 mmol/L)
- In hyponatremia, body fluids are diluted and cells swell from decreased extracellular fluid osmolality
- Severe hyponatremia (sodium level below 110 mEq/L [SI, 110 mmol/L]) can lead to seizures, coma, and permanent neurologic damage

Question 20

Hyponatremia can be triggered by?

Answer 20

1. sodium loss
2. water gain
   - dilutional hyponatremia
3. inadequate sodium intake
   - depletional hyponatremia

Question 21

Types of hyponatremia?

Answer 21

1. hypovolemic
   - with decreased extracellular fluid volume
2. hypervolemic
   - with increased extracellular fluid volume
3. isovolumic
   - with extracellular fluid volume equal to intracellular fluid volume

Question 22

Causes of hypovolemic hyponatremia causes - urinary Na+ >20 mmol/L?

Answer 22

renal loses
1. diuretic excess
2. mineralocorticoid deficiency
3. salt losing nephropathy
4. bicarbonaturia with renal tubular acidosis and metabolic alkalosis
5. ketonuria
6. osmotic diuresis
7. cerebral salt wasting

Question 23

Causes of hypovolemic hyponatremia causes - urinary Na+ <20 mmol/L?

Answer 23

extrarenal loses
1. vomiting
2. diarrhea
3. third spacing of fluids in burns
4. pancreatitis
5. trauma

Question 24

Euvolemic hyponatremia causes?

Answer 24

1. glucocorticoid deficiency
2. hypothyroidism
3. stress - physical or psychological
4. drugs
5. SIADH

Question 25

Hypervolemic hyponatremia causes - urinary Na+>20mmol/L?

Answer 25

acute or chronic renal failure

Question 26

Hypervolemic hyponatremia causes - urinary Na+<20mmol/L?

Answer 26

1. nephrotic syndrome
2. cirrhosis
3. cardiac failure

Question 27

Drugs that cause hyponatremia?

Answer 27

1. anticonvulsants
2. antineoplastics
3. antidiuretics

Question 28

Diagnostic tests for hyponatremia?

Answer 28

1. Serum osmolality below 280 mOsm/kg (dilute blood).
2. Serum sodium level below 135 mEq/L (SI, 135 mmol/L) or less than LLN
3. Urine specific gravity below 1.010 (or increased urine specific gravity and urine sodium level in a patient with SIADH secretion).

Question 29

Rapid correction of severe hyponatremia can cause?

Answer 29

osmotic demylination of the cord (Central Pontine Myelinosis)