Electrolyte Imbalance: Na+ Disorders

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Questions and Answers

What is the most likely urine Na+ level indication for hepatic cirrhosis?

Around 15 mmol/d

Exactly 25 mmol/d

Less than 20 mmol/d (correct)

Over 30 mmol/d

Which disorder is associated with increased water retention due to decreased plasma proteins?

Diabetes insipidus

Hepatic cirrhosis (correct)

Congestive heart failure

Renal tubular disorder

What physiological mechanism predominantly leads to fluid retention in response to low plasma volume?

Decreased AVP production

Decreased water intake

Increased AVP production (correct)

Increased colloid osmotic pressure

What condition can result from excess water intake leading to hyponatremia?

Polydipsia Signup and view all the answers

Which of the following disorders is characterized by a decreased colloid osmotic pressure?

Nephrotic syndrome Signup and view all the answers

How does SIADH affect sodium levels in the body?

It results in dilution of sodium. Signup and view all the answers

What is a common cause of hypernatremia?

Excess water loss Signup and view all the answers

Which of the following disorders could cause dilution of serum sodium due to fluids migrating to tissue?

Hepatic cirrhosis Signup and view all the answers

What is considered a medical emergency when related to acute hyponatremia?

Serum Na+ level below 120 mmol/L Signup and view all the answers

Which treatment approach is typically used to manage hyponatremia?

Fluid restriction and administration of hypertonic saline Signup and view all the answers

What condition may result in pseudohyperkalemia?

In vitro hemolysis Signup and view all the answers

Which symptom is associated with severe hypercalcemia?

Confusion Signup and view all the answers

What factor influences the treatment of hyponatremia?

Severity and duration of hyponatremia Signup and view all the answers

What is typically monitored to guide treatment for hyperlipidemia?

Serum and urine electrolytes Signup and view all the answers

What is the approved treatment for euvolemic or hypervolemic hyponatremia?

Conivaptan Signup and view all the answers

What factor is NOT considered when treating hyponatremia?

Severity of blood pressure Signup and view all the answers

What is the primary role of Cl− in the body?

To maintain osmolality and electric neutrality Signup and view all the answers

Why might serum reference intervals for K+ be higher than plasma reference intervals?

Clotting of serum releases K+ from ruptured cells Signup and view all the answers

How is excess Cl− primarily eliminated from the body?

Through urine and sweat Signup and view all the answers

Which method is preferred for measuring Cl− levels in the body?

Ion-selective electrode (ISE) Signup and view all the answers

What causes a spurious hyperkalemia in serum samples?

Elevated platelet counts during clotting Signup and view all the answers

What is the primary effect of excessive sweating on electrolyte balance?

Stimulates aldosterone secretion Signup and view all the answers

In which part of the nephron is Cl− reabsorbed in conjunction with Na+?

Proximal tubules Signup and view all the answers

Why is urine collection over a 24-hour period suggested?

To avoid diurnal variation in excretion Signup and view all the answers

What characterizes diabetes insipidus?

Copious production of dilute urine Signup and view all the answers

In which condition may a reset osmostat occur?

Primary hyperaldosteronism Signup and view all the answers

What can cause hypernatremia aside from diabetes insipidus?

Excess salt intake or administration of hypertonic solutions Signup and view all the answers

What happens to urine osmolality in renal loss of water?

Low or normal osmolality Signup and view all the answers

Which symptom is most commonly associated with hypernatremia?

Altered mental status Signup and view all the answers

What is a common cause of excess water loss that can lead to hypernatremia?

Acute tubular necrosis Signup and view all the answers

How is urine osmolality evaluated in the context of hypernatremia?

Should be assessed for increased levels Signup and view all the answers

What serum Na+ level indicates a 60% mortality rate in hypernatremia?

160 mmol/L Signup and view all the answers

Which condition is likely to increase K+ excretion in a person with renal tubular acidosis (RTA)?

Decreased tubular excretion of H+ Signup and view all the answers

What is the main effect of hyperaldosteronism on K+ levels?

Causes hypokalemia and metabolic alkalosis Signup and view all the answers

During IV K+ replacement therapy, what condition poses the highest risk for hyperkalemia?

Renal insufficiency Signup and view all the answers

What role does Mg2+ play in potassium levels in the body?

Diminishes Na+, K+-ATPase activity Signup and view all the answers

Which of the following scenarios is least likely to cause hyperkalemia?

Normal renal function Signup and view all the answers

How does acute myelogenous leukemia contribute to K+ levels?

Disrupts normal renal function Signup and view all the answers

Which of the following is a common cause of hyperkalemia during hospitalization?

Therapeutic K+ administration Signup and view all the answers

What is the initial effect of an acute oral load of K+ in healthy individuals?

Increases plasma K+ levels temporarily Signup and view all the answers

Study Notes

Hyponatremia

Urine Na+ levels are usually less than 20 mmol/d in disorders like congestive heart failure, nephrotic syndrome, and hepatic cirrhosis.
Low plasma volume can cause AVP to be produced, leading to fluid retention and dilution of Na+.
Excess water intake can cause mild or severe hyponatremia.
SIADH causes increased water retention due to increased AVP production.
Plasma reference intervals for K+ tend to be slightly higher than serum intervals.
Elevated platelet counts can cause spurious hyperkalemia due to K+ release during clotting.
Urine specimens should be collected over a 24 hours period to eliminate diurnal variation influence.

Hypernatremia

Results from loss of water in diabetes insipidus, either due to kidney's inability to respond to AVP (nephrogenic) or impaired AVP secretion (central).
Diabetes insipidus is characterized by copious production of dilute urine.
Excess water loss can also occur in renal tubular disease, leading to inability of tubules to fully concentrate urine.
Urine osmolality is essential for evaluating causes of hypernatremia.
With renal water loss, urine osmolality is low or normal.
With extrarenal fluid losses, urine osmolality is increased.

Hyperkalemia

Common causes include renal insufficiency, diabetes mellitus, metabolic acidosis, and therapeutic K+ administration.
In healthy individuals, an acute oral load of K+ briefly increases plasma K+ as most of the absorbed K+ quickly moves intracellularly.
Normal cellular processes gradually release excess K+ back into the plasma for renal excretion.

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Description

This quiz covers the key concepts and mechanisms related to hyponatremia and hypernatremia, including the causes, effects, and clinical implications of sodium disturbances in the body. Dive into important conditions like SIADH and diabetes insipidus while reinforcing your understanding of urine and plasma sodium levels.