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Questions and Answers
What defines hyponatremia in terms of serum/plasma sodium levels?
What defines hyponatremia in terms of serum/plasma sodium levels?
- Less than 135 mmol/L (correct)
- Less than 145 mmol/L
- Less than 130 mmol/L
- Less than 120 mmol/L
Which condition is primarily associated with increased AVP (ADH) production?
Which condition is primarily associated with increased AVP (ADH) production?
- Congestive Heart Failure
- Nephrotic Syndrome
- SIADH (correct)
- Cirrhosis
What lab result is most commonly implicated in pseudohyponatremia?
What lab result is most commonly implicated in pseudohyponatremia?
- In vitro hemolysis
- Hyperlipidemia (correct)
- Diabetes Insipidus
- Hyperproteinemia (correct)
Which of the following symptoms is associated with serum sodium levels between 125 and 130 mmol/L?
Which of the following symptoms is associated with serum sodium levels between 125 and 130 mmol/L?
How does cirrhosis affect plasma proteins and colloidal osmotic pressure?
How does cirrhosis affect plasma proteins and colloidal osmotic pressure?
What is a common cause of hypernatremia related to fluid loss?
What is a common cause of hypernatremia related to fluid loss?
Which condition is associated with general edema?
Which condition is associated with general edema?
What effect does aldosterone have on sodium excretion?
What effect does aldosterone have on sodium excretion?
What process describes the movement of substances from blood into the nephron?
What process describes the movement of substances from blood into the nephron?
What is the main function of the glomerulus?
What is the main function of the glomerulus?
Which process primarily involves the use of energy by tubular epithelial cells?
Which process primarily involves the use of energy by tubular epithelial cells?
What role does chloride (Cl-) play within the extracellular fluid?
What role does chloride (Cl-) play within the extracellular fluid?
How does chloride maintain electroneutrality in the body?
How does chloride maintain electroneutrality in the body?
What is the volume of blood filtered per minute known as?
What is the volume of blood filtered per minute known as?
What describes the movement of substances from the tubular lumen to blood?
What describes the movement of substances from the tubular lumen to blood?
What happens during tubular secretion?
What happens during tubular secretion?
What type of electrolyte moves toward the cathode?
What type of electrolyte moves toward the cathode?
Which mechanism requires energy to transport ions across membranes?
Which mechanism requires energy to transport ions across membranes?
What is one of the primary functions associated with potassium ions?
What is one of the primary functions associated with potassium ions?
What includes the ions involved in blood coagulation?
What includes the ions involved in blood coagulation?
What is the passive movement of ions across a membrane called?
What is the passive movement of ions across a membrane called?
What does osmolality primarily depend on?
What does osmolality primarily depend on?
Which electrolytes are primarily involved in acid-base balance?
Which electrolytes are primarily involved in acid-base balance?
What effect does increased blood osmolality have on the secretion of Arginine Vasopressin Hormone (AVP)?
What effect does increased blood osmolality have on the secretion of Arginine Vasopressin Hormone (AVP)?
What is the primary function of chloride ions in the body?
What is the primary function of chloride ions in the body?
Hypochloremia is primarily associated with which of the following conditions?
Hypochloremia is primarily associated with which of the following conditions?
Which part of the kidney actively reabsorbs chloride ions?
Which part of the kidney actively reabsorbs chloride ions?
What causes hyperchloremia?
What causes hyperchloremia?
Which anticoagulant is preferred for chloride ion testing?
Which anticoagulant is preferred for chloride ion testing?
What does a method using coulometric generation of silver ions help to quantify?
What does a method using coulometric generation of silver ions help to quantify?
Patients with metabolic alkalosis often exhibit which chloride condition?
Patients with metabolic alkalosis often exhibit which chloride condition?
How does hemolysis affect chloride measurement in serum or plasma?
How does hemolysis affect chloride measurement in serum or plasma?
Which method is most commonly used for mercurimetric titration?
Which method is most commonly used for mercurimetric titration?
What percentage of magnesium in the human body is found in bone?
What percentage of magnesium in the human body is found in bone?
What role does magnesium play in the body?
What role does magnesium play in the body?
Which of the following sources is a rich source of magnesium?
Which of the following sources is a rich source of magnesium?
What is the renal threshold for magnesium?
What is the renal threshold for magnesium?
What percentage of magnesium serum is bound to proteins?
What percentage of magnesium serum is bound to proteins?
Which hormone increases the renal reabsorption of magnesium?
Which hormone increases the renal reabsorption of magnesium?
What is the end product of the mercurimetric titration using diphenylcarbazone?
What is the end product of the mercurimetric titration using diphenylcarbazone?
Study Notes
Blood Volume Status
- Affects sodium excretion through aldosterone, angiotensin II, and ANP.
- Hyponatremia - loss of sodium due to an increase in water volume.
Hyponatremia
- One of the most common electrolyte disorders.
- Can be assessed by the cause of the decrease or the osmolality level.
- Defined as a serum/plasma sodium level less than 135 mmol/L.
- Levels below 130 mmol/L are clinically significant.
Causes of Hyponatremia
- Dilutional:
- SIADH (Syndrome of Inappropriate Anti-diuretic Hormone Secretion)
- General Edema (Congestive Heart Failure, Cirrhosis, Nephrotic Syndrome)
- Hyperglycemia
- Artifactual:
- Pseudohyponatremia, caused by analytical errors.
- Hyperlipidemia
- Hyperproteinemia
- In vitro hemolysis
Chloride (Cl-)
- Major extracellular anion.
- The only anion to serve as an enzyme activator.
- Chief counter ion of Sodium in the extracellular fluid.
- Concentration:
- 103 mmol/L with median plasma and interstitial fluid concentrations.
- 154 mmol/L inorganic anion concentration.
- Erythrocytes (RBC): 45 to 54 mmol/L
- Other Tissue Cells: only -1 mmol/L
Functions of Chloride
- Maintenance of water distribution.
- Osmotic Pressure.
- Anion-Cation Balance in the ECF.
- Maintains electrical neutrality.
Chloride Absorption
- Chloride ions in food are almost completely absorbed from the intestinal tract.
Chloride in Glomeruli
- Filtered and passively absorbed with Sodium.
Chloride in Loop of Henle (thick ascending limb)
- Actively reabsorbed by the chloride pump.
- Promotes passive reabsorption of Sodium.
Hypochloremia
- Decreased plasma concentration of Chloride.
- Occurs with:
- Excessive loss of Chloride from prolonged vomiting, diabetic ketoacidosis, aldosterone deficiency, or salt losing renal diseases such as pyelonephritis.
- High serum bicarbonate concentration.
- Compensated respiratory acidosis or metabolic alkalosis.
Hyperchloremia
- Increased plasma concentration of Chloride.
- Occurs with excess loss of bicarbonate as a result of:
- GI losses
- Renal tubular acidosis (RTA)
- Metabolic acidosis
Determination of Chloride
- Specimen: Serum or Plasma
- Lithium Heparin: the anticoagulant of choice.
- Whole blood samples: Consult the instrument's operation manual for acceptability.
- Urine Analysis: 24-hour collection is the specimen of choice due to large diurnal variation.
Chloride Methods
- Ion-Selective Electrode (ISE):
- Most commonly used.
- An ion-exchange membrane selectively binds Chloride ions.
- Amperometric-coulometric Titration:
- Coulometric generation of silver ions (Ag+), which combine with Chloride to quantitate the Chloride concentration.
- Mercurimetric Titration (Schales and Schales Method):
- Indicator: diphenylcarbazone.
- End product: HgCl2.
- Whitehorn Titration Method:
- Reagent: diphenylcarbazone.
- End Product: reddish complex.
Magnesium (Mg2+)
- Fourth most abundant cation in the body and second most abundant intracellular ion.
- Average human body (70 kg) contains 1 mole (24g) of Mg2+.
- Distribution:
- 53% in Bone
- 46% in muscle and other organs and Soft Tissue
- Less than 1% is present in Serum and Red Blood Cells
- Essential cofactor of more than 300 enzymes.
- 1/3 of serum Mg2+ is bound to a protein (Albumin).
- Remaining 2/3:
- 61% exists in the free or ionized state (physiologically active).
- 5% is complexed with other ions (PO4- and citrate).
Regulation of Magnesium
- Absorption: Rich sources of Mg2+: raw nuts, dry cereal, “hard” drinking water, vegetables, meats.
- Renal Threshold: ~0.60–0.85 mmol/L.
- Factors Affecting Mg2+ levels:
- Parathyroid hormone (PTH): Increases renal reabsorption of Mg2+ and enhances absorption in the intestine.
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Description
This quiz covers key concepts related to blood volume status and hyponatremia. Learn about how sodium excretion is influenced by various factors, the definitions and causes of hyponatremia, and the role of chloride as an extracellular anion. Understand the clinical significance of sodium levels and potential diagnostic considerations.
