Sodium and Potassium Flashcards
Has a concentration 20x greater inside the cells than outside
Potassium
the most abundant cation in the ECF
Sodium
Functions of Potassium
- regulation of neuromuscular excitability
- regulation of contraction of the heart
- regulation of ICF volume and H+ conc
represent of 90% of all extracellular cations
Sodium
Organ that is important in the regulation of K+ balance
Kidney
Three processes in the regulation of Sodium
- intake of water
- excretion of water, as affected by ADH
- blood volume status
True or false. Sodium concentration in the ECF is much smaller than inside the cells
False
Decreased serum Na+ concentration (less than 135mmol/L)
Hyponatremia
One of the most common electrolyte disorders
Hyponatremia
causes of hyponatremia
- increased sodium loss
- increased water retention
- water imbalance
Symptoms of Hyponatremia
- gastroinestinal
- neuropsyhchiatric
- dba sbi niya nde na itatanong mga symptoms?
TReatment of hyponatremia
- fluid restriction
- administration of hypertonic saline
- AVPR antagonist Conivaptan
method of choice for sodium determination
ion slective electrode (ISE)
Increase in water retention associated with pulmonary disease, malignancies, CNS disorders, infections or trauma
Syndrome of inappropriate antidiuretic hormone
occur when Na is measured using indirect ISE
pseudohyponatremia
hyponatrmia with low osmolality
- increased sodium loss
- increased water retention
hyponatrmia with normal osmolality
- increased in non sodium cations
- pseudohyponatremia
- pseudohyperkalemia
non sodium cations
Li, K, Mg, Ca, gamma globulins
hyponatremia with high osmolality
- hyperglycemia
- mannitol infusion
excess loss of water relative to sodium loss; decreased water intake; increased sodium intake or retention
hypernatremia
causes of hypernatremia
- diabetes insipidus
-renal tubular disorders
-prolonged diarrhea
-profuse sweating
-severe burns
-
correlation with sodium osmolality (<300 mOsm/kg)
diabetes insipidus
correlation with osmollality (300-700 mOsm/kg
partial defect in ADH release
correlation with osmolality (>700 mOsm/kg)
loss of thirst, insensible loss of water, GI loss of hypotonic fluid, excess sodium intake
People with decreased water intake
- older persons
- infants
- mentally impaired
increased sodium intake or retention
- hyperaldosteronism
- sodium bicarbonate excess
- dialysis fluid excess
Marked hemolysis in sodium determination is caused by
dilution
marked hemolysis in sodium determination means
falsely decreased; decreased level of sodium
Reference method for sodium determination
Atomic Absorption Spectrometer
color of sodium in flame emission spectrophotometer
intense yellow
Two electrodes used in ion selective electrode
- reference electrode
- measuring electrode
only 2% in plasma
potassium
Causes of hypokalemia
- GI loss
- renal loss
- cellular shift
- decreased intake
<3.4 mmol/L of potassium
hypokalemia
regulation of potassium
- hypoxia, hypomagnesia, digoxin
- insulin
- catecholamine
Diuretic used in renal loss
Thiazides
Treatment of hypokalemia
- oral KCl
- IV replacement
- diet with high K
- banana
Causes of hyperkalemia
- decreased renal excretion
- cellular shift
- increased intake
- artifactual
Artifactual causes of hyperkalemia
- sample hemolysis
- thrombocytosis
- prolonged tourniquet use
- excessive fist clenching
increases the cellular uptake of K+
cellular shift
promotes the entry of K+ into skeletal muscle and liver cell
insulin overdose
diseases in decreased renal excretion
- acute or chronic renal failure
- hypoaldosteronism
- Addison’s disease
Produces a hyperosmolar plasma that pulls water and potassium from cells
Diabetes Mellitus
Drugs for hyperkalemia
- captopril
- nonsteroidal anti-inflammatory
- spironolactone
- digoxin
- cyclosporine
- heparin theraphy
inhibits renal response to aldosterone
cyclosporine
inhibits aldosterone secretion
heparin theraphy
treatment of hyperkalemia
administration of sodium bicarbonate, glucose or insulin
sources of error in potassium determination
- excessive fist clenching
- exercising the arms prior to venipuncture
- storage on ice promotes release of potassium from cells
most common cause of artifactual hyperkalemia
hemolysis
spx of choice preferred in cases of thrombocytosis in potassium determination
plasma
reference method of potassium determination
AAS
colorimetric method of potassium detrermination
Hoffman method (sodium tetraphenylboron or sodium cobaltinitrite) boron ba yun???