LAB - Sodium, Potassium, Chloride Flashcards
What is the major extracellular cation?
Sodium (Na⁺)
What percentage of extracellular cations does sodium account for?
90%
Which pump maintains higher sodium concentration in extracellular fluid?
Na⁺-K⁺ ATPase pump
What hormone regulates sodium reabsorption in the kidneys?
Aldosterone
Where is most sodium reabsorbed in the kidneys?
Proximal tubules (80%)
Which part of the kidney reabsorbs 20-25% of sodium?
Loop of Henle
What is the normal reference range for sodium in serum/plasma?
135-145 mmol/L
What is the normal sodium range in cerebrospinal fluid (CSF)?
135-150 mmol/L
What condition is characterized by sodium levels above 145 mmol/L?
Hypernatremia
What is the main cause of hypernatremia?
Excessive water loss
Name a condition linked to hypernatremia due to sodium retention.
Conn’s syndrome (Hyperaldosteronism)
What condition is characterized by sodium levels below 135 mmol/L?
Hyponatremia
What sodium concentration is considered a medical emergency?
<120 mmol/L for 48 hours
What are common causes of hyponatremia?
Diuretic use, renal failure, and SIADH
Which sodium determination method is preferred for hyperlipidemic samples?
Direct ISE
Which sodium method requires sample dilution?
Indirect ISE
What color is observed in the colorimetric method for sodium?
Yellow-brown
What reagent is used in Trinder’s colorimetric method for sodium?
Magnesium uranyl acetate
What is the function of aldosterone in sodium regulation?
Stimulates sodium retention and potassium excretion
What is the major intracellular cation?
Potassium (K⁺)
How much more concentrated is potassium in RBCs than in plasma?
20 times greater
What percentage of potassium is found in plasma?
2%
Where is potassium reabsorbed in the kidneys?
Proximal tubules
What process is responsible for potassium secretion in the kidneys?
Distal tubule secretion (regulated by aldosterone)
What is the normal potassium range in serum?
3.5-5.2 mmol/L
What is the potassium reference range in urine (24-hour collection)?
25-125 mmol/day
What potassium level is considered hypokalemia?
<3.0 mmol/L
What are common causes of hyperkalemia?
Renal failure, acidosis, and Addison’s disease
What are common causes of hypokalemia?
Diuretic use, alkalosis, and insulin overdose
What condition involves falsely elevated potassium levels?
Pseudohyperkalemia
What situations can cause pseudohyperkalemia?
Hemolysis, thrombocytosis, prolonged tourniquet use
Which method is the preferred choice for potassium determination?
ISE (Ion-Selective Electrode)
What potassium-specific carrier is used in ISE methods?
Valinomycin
Which potassium determination method uses sodium tetraphenylboron?
Hoffman’s colorimetric method
What is the recommended anticoagulant for potassium analysis?
Heparin
Why should whole blood not be stored on ice for potassium testing?
It promotes potassium release from cells
What is the most common cause of artifactual hyperkalemia?
Hemolysis
What is the major extracellular anion?
Chloride (Cl⁻)
What is the normal reference range for chloride in plasma/serum?
98-104 mmol/L
What is the normal chloride range in urine (24-hour collection)?
110-250 mmol/day
What condition is characterized by chloride levels above 104 mmol/L?
Hyperchloremia
What condition is characterized by chloride levels below 98 mmol/L?
Hypochloremia
What is the most common cause of hyperchloremia?
Loss of bicarbonate (e.g., metabolic acidosis)
What are common causes of hypochloremia?
Prolonged vomiting, diabetic ketoacidosis
Which chloride determination method uses mercuric thiocyanate?
Colorimetric method
Which chloride method forms a blue color with diphenylcarbazone?
Mercurimetric titration
What reagent is used in Cotlove’s amperometric method for chloride?
Silver (Ag²⁺)
What is the chloride shift?
The exchange of chloride ions with bicarbonate ions in red blood cells
Which part of the kidney reabsorbs chloride passively?
Proximal tubules
Where does active chloride reabsorption occur?
Ascending limb of the loop of Henle
What electrolyte imbalance is commonly associated with cystic fibrosis?
Elevated sweat chloride levels
What hormone conserves chloride during excessive sweating?
Aldosterone
Why may marked hemolysis cause decreased chloride levels?
Due to the dilutional effect
What specimen is preferred for chloride urine analysis?
24-hour urine collection
What condition is associated with chloride imbalance and respiratory issues?
Compensated respiratory acidosis
What condition leads to chloride loss via GI disturbances?
Prolonged diarrhea
What method is most commonly used for chloride determination?
ISE (Ion-Selective Electrode)
What is the primary symptom of severe hypernatremia?
Central nervous system (CNS) disturbances
What is a common cause of sodium imbalance in hospitalized patients?
Intravenous (IV) sodium infusions
What medical condition causes increased sodium retention?
Hyperaldosteronism (Conn’s syndrome)
What condition results from decreased aldosterone levels?
Hypoadrenalism
Which specimen types are suitable for sodium analysis?
Serum, plasma, urine, and sweat
Why is hemolysis less likely to affect sodium levels?
Sodium is primarily an extracellular electrolyte.
What is the main risk of sodium levels changing too rapidly?
Brain damage due to cerebral edema or osmotic demyelination
Which condition results from increased sodium loss via the gastrointestinal tract?
Prolonged diarrhea
What condition occurs when sodium levels fall below 125 mmol/L?
Severe neuropsychiatric symptoms
Which hormone is released in response to low sodium levels?
Aldosterone
What is the primary purpose of the sodium-potassium pump?
To maintain sodium outside the cell and potassium inside
Which sodium determination method uses zinc uranyl acetate as a precipitant?
Suderman and Delory method
What is the primary role of potassium in the body?
Regulate neuromuscular activity and heart contraction
What is the effect of potassium imbalance on heart rhythm?
It can cause arrhythmias or cardiac arrest.
What potassium level is associated with ECG changes?
6-7 mmol/L
What is a common symptom of hypokalemia?
Muscle cramps and weakness
Which electrolyte imbalance can be caused by excessive insulin administration?
Hypokalemia
Which organ is primarily responsible for potassium excretion?
Kidneys
What is the main risk of potassium levels changing too rapidly?
Cardiac arrest or severe muscle weakness
What potassium reagent is commonly used in the Hoffman method?
Sodium tetraphenylboron
Why should potassium samples be centrifuged immediately?
To prevent potassium release from cells
Which anticoagulant is recommended for potassium analysis?
Heparin
Why does storing whole blood on ice cause potassium elevation?
Potassium leaks from cells at low temperatures.
What potassium-specific error occurs due to fist clenching before blood collection?
Pseudohyperkalemia
How does acidosis affect potassium levels?
It causes potassium to shift from cells into the bloodstream.
Which potassium imbalance is common in patients with Addison’s disease?
Hypokalem
What condition results in excessive potassium loss through the gastrointestinal tract?
Prolonged vomiting or diarrhea
What is the primary function of chloride in the body?
Maintain osmolality, blood volume, and electroneutrality
Which organ regulates chloride through passive and active reabsorption?
Kidneys
What method of chloride determination produces a reddish-brown color?
Mercuric thiocyanate colorimetric method
What condition results from excessive loss of chloride via vomiting?
Hypochloremia
