Sodium Flashcards
major cation outside the cell
sodium
most abundant cation in ECF (regardless of being intravascular or interstitial)
sodium
principal osmotic particle outside the cell
sodium
reference range of sodium in serum
135 - 145 mmol/L
reference range of sodium in CSF
136 - 150 mmol/L
reference range of sodium in urine
40 - 220 mmol/day
condition where the threshold critical value of Na is 160 mmol/L or more
hypernatremia
condition where the threshold critical value of Na is 120 mmol/L or less
hyponatremia
Na stands for
natrium
concentration of substance in the blood wherein it stops reabsorption by the kidneys
renal threshold
renal threshold of Na
110 - 130 mmol/L
2 factors that maintains sodium conc. in serum/plasma
- water intake (increased water, decreased Na [diluted by water])
- water excretion (more water excreted increases Na conc.)
ATP driven that promotes exit of 3 sodium outside the cell in return with 2 potassium
Prevents osmotic rupture of cells
Sodium-Potassium-ATPase ion pump
how does Sodium-Potassium-ATPase ion pump prevents osmotic cell rupture?
excretion of 3 sodium also secretes 3 water molecules
(decreases water content inside the cell, thus, no rupture)
2 Functions of Sodium-Potassium-ATPase ion pump
maintains increased concentration of intracellular POTASSIUM
maintains increased concentration of extracellular SODIUM
defense to hyperosmolality and hypernatremia
thirst
increased water excretion leads to increased or decreased sodium?
increased
blood volume status is affected by Na excretion through:
aldosterone
angiotensin II
ANP
• blocks aldosterone and renin secretion
• inhibits action of angiotensin II and vasopressin
Atrial Natriuretic Peptide
60-75% of filtered sodium are reabsorbed by
PCT
how is sodium regulated in kidneys? (2)
filtered Na are reabsorbed by PCT
reabsorption of Na in DCT by aldosterone
decreased plasma Na concentration and its value
Hyponatremia (<135 mmol/L)
most common electrolyte disorder
Hyponatremia
value where hyponatremia symptoms starts
125-130 mmol/L
value of sodium that results to severe neuropsychiatric symptoms or momentary memory loss
<125 mmol/L
glucose condition that causes hyponatremia
hyperglycemia
(DM also causes electrolyte imbalance wherein water released in ECF dilutes Na)
urine sodium of 20 mmol/day indicates what condition
renal sodium and water loss
100 mg/dL INCREASE in glucose is equivalent to?
1.6 mmol/L DECREASE in sodium
(water is released every glucose uptake by the cell (by insulin), which dilutes Na (hyponatremia)
4 general causes of hyponatremia
• increased sodium loss
• increased water retention
• water imbalance
• pseudohyponatremia
explain the mechanism of hypoadrenalism in increasing sodium loss
↓ aldosterone production —> no sodium is reabsorbed in DCT —> sodium is loss in urine
mechanism of potassium deficiency (hypokalemia) in increasing sodium loss
decreased potassium —> promotes potassium retention in KIDNEYS —> sodium excretion (↓ Na)
retained K = excretes Na
mechanism of diuretics (thiazides) in increasing sodium loss
promotes urine flow
(by inhibiting renal Na reabsorption in DCT)
mechanism of ketonuria in increasing sodium loss
ketones are loss along with Na in urine
ketone loss = Na loss
why does ↑ water retention causes hyponatremia
dilutes Na
conditions that promotes ↑ water retention leading to hyponatremia
• renal failure
• nephrotic syndrome
• hepatic cirrhosis
• CHF
conditions that promotes water imbalance leading to hyponatremia
• polydipsia (excessive thirst) - dilutes plasma and electrolytes (Na)
• SIADH - ↑ADH; ↓urine output; ↑blood volume; dilutes Na
Sodium measurement method that leads to pseudohyponatremia (systematic error)
INDIRECT Ion Selective Electrode (dilution requiring)
if patient has:
• hyperlipidemia
• hyperproteinemia
lipids and proteins displaces Na during measurement—> false ↓
↑ plasma Na conc. and its value
hypernatremia (>145 mmol/L)
True or False:
Water deficit (↓ blood vol) of 1-2% causes thirst which affects plasma concentration
TRUE
indicative of hypothalamic dse due to nonresponsive hypothalamus that can no longer promote THIRST and increases vasopressin
chronic hypernatremia
moderate water deficit value
150-160 mEq/L or mmol/L sodium
severe water deficit value
> 165 mEq/L or mmol/L sodium
most common cause of hypernatremia
excess water loss
mechanism of diabetes insipidus in causing increased sodium
EXCESS WATER LOSS:
polyuria —> vasopressin deficiency —> increase urination —> ↑ Na conc.
mechanism of renal tubular disorder in causing increased sodium
EXCESS WATER LOSS:
impairment to concentrate urine (in same conc.) SG must be 1.010
profuse sweating and hyperventilation causes how many loss of water per day
1 liter
decreased water intake in population of old people, infants, and mental impairment causes hypernatremia or hyponatremia?
hypernatremia
conditions that has an ↑ sodium intake or retention
• hyperaldosteronism (Conn’s dse)
• sodium bicarbonate infusion
• ↑ NaCl administration
• Sea water ingestion
drinking sea water leads to?
hypernatremia and excessive thirst
accepted specimen for Na analysis
- serum
- plasma
- 24 hr urine
- sweat
- whole blood
additives used if plasma specimen is utilized for Na analysis
lithium heparin
lithium oxalates
ammonium heparin
variable that causes false ↓ Na
MARKED hemolysis due to dilutional effect
5 Methods used for Na analysis
- Gibson and Cooke Pilocarpine Iontophoresis
- Ion Selective/Specific Electrode
- AAS
- Emission Flame Photometry
- Albanese Lein (chemical method)
method of sweat sample collection
Gibson and Cooke Pilocarpine Iontophoresis
sweat inducers used in Gibson and Cooke Pilocarpine Iontophoresis
Pilocarpine
Mild current (iontophoresis)
output required in Gibson and Cooke Pilocarpine Iontophoresis
> 50 mg sweat within 30 mins
what must be done to the sweat sample after collection?
tightly sealed (volatile/easily evaporates)
Na membrane responsible for selectivity of ISE
Glass Aluminum Silicate
measurement of non-excitable ion and excitable ion, respectively
AAS
EFP
reagents used in Albanese Lein
Cupric sulfate
NaOh
