Hyponatremia and ADH Release
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Questions and Answers

Which of the following conditions is most likely to cause hypovolemic hyponatremia?

  • Addison's disease
  • Liver failure
  • Severe diarrhea (correct)
  • Myxedema

    • What is the primary cause of dilutional hyponatremia in the presence of renal failure?

  • Excessive Na+ intake
  • Decreased ADH secretion
  • Inadequate water intake
  • H2O intake without Na+ retention (correct)

    • Which of the following medications is most likely to cause nonosmotic ADH secretion?

  • Chlorpropamide
  • Tolbutamide
  • Carbamazepine
  • All of the above (correct)

    • What is the characteristic of euvolemic hyponatremia?

    <p>No significant change to total body Na+</p> Signup and view all the answers

    Which of the following conditions is most likely to cause hypervolemic hyponatremia?

    <p>CHF and Liver Failure</p> Signup and view all the answers

    What is the primary cause of hyponatremia in hypervolemic hyponatremia?

    <p>Decrease in effective circulating volume</p> Signup and view all the answers

    Which of the following is a common cause of nonosmotic ADH secretion?

    <p>All of the above</p> Signup and view all the answers

    What is the effect of ADH on the kidneys in hypervolemic hyponatremia?

    <p>Antidiuretic effect</p> Signup and view all the answers

    What is the osmotic threshold for ADH release in some individuals with SIADH?

    <p>Abnormally low</p> Signup and view all the answers

    What happens to ADH secretion in some individuals with SIADH?

    <p>It is erratic and independent of osmotic control</p> Signup and view all the answers

    At what plasma osmolality do symptoms of hyponatremia typically occur?

    <p>Below 240 mOsm/kg</p> Signup and view all the answers

    What is characteristic of a small group of individuals with SIADH?

    <p>Low levels of ADH</p> Signup and view all the answers

    What is the primary cause of hyponatremia in SIADH?

    <p>Inappropriate ADH secretion</p> Signup and view all the answers

    What is the term for the abnormal regulation of ADH secretion in SIADH?

    <p>Reset osmostat</p> Signup and view all the answers

    What type of hyponatremia is characterized by low levels of ADH?

    <p>Euvolemic hyponatremia</p> Signup and view all the answers

    What is the term for ADH secretion that is not regulated by osmotic control?

    <p>Nonosmotic ADH secretion</p> Signup and view all the answers

    Which of the following conditions is most likely to cause hypovolemic hyponatremia?

    <p>Diuretic abuse</p> Signup and view all the answers

    What is the most common cause of euvolemic hyponatremia?

    <p>SIADH</p> Signup and view all the answers

    Which of the following is a non-osmotic stimulus for ADH secretion?

    <p>Emotional stress</p> Signup and view all the answers

    What is the term for hyponatremia caused by excessive water intake?

    <p>Dilutional hyponatremia</p> Signup and view all the answers

    Which of the following is a cause of hypervolemic hyponatremia?

    <p>Heart failure</p> Signup and view all the answers

    What is the term for hyponatremia caused by excessive ADH secretion?

    <p>SIADH</p> Signup and view all the answers

    Which of the following is a cause of euvolemic hyponatremia?

    <p>Hypothyroidism</p> Signup and view all the answers

    What is the term for hyponatremia caused by excessive sodium loss?

    <p>Hypovolemic hyponatremia</p> Signup and view all the answers

    Which of the following conditions can cause hypovolemic hypernatremia?

    <p>Burns</p> Signup and view all the answers

    What is the most common cause of hypernatremia resulting from osmotic diuresis?

    <p>Hyperglycemia</p> Signup and view all the answers

    Which of the following is a cause of hypernatremia without a disturbance in sodium balance?

    <p>Excess sweating</p> Signup and view all the answers

    What is the underlying defect in diabetes insipidus?

    <p>Defect in production or release of ADH</p> Signup and view all the answers

    What can occur in a patient with diabetes insipidus if they do not have access to water?

    <p>Hypernatremia without a disturbance in sodium balance</p> Signup and view all the answers

    Which of the following can prevent maximally concentrated urine, predisposing to hypernatremia?

    <p>Renal insufficiency</p> Signup and view all the answers

    What is the consequence of excess loss of water from the body that is not adequately replaced?

    <p>Hypernatremia</p> Signup and view all the answers

    What can cause hypernatremia in a patient with nonketotic hyperosmolar hyperglycemic coma of diabetes?

    <p>Osmotic diuresis</p> Signup and view all the answers

    What is the primary mechanism of hypovolemic hyponatremia?

    <p>Excessive Na+ loss</p> Signup and view all the answers

    Which of the following is a cause of euvolemic hyponatremia?

    <p>SIADH</p> Signup and view all the answers

    What is the characteristic of hypervolemic hyponatremia?

    <p>Total body Na+ is increased</p> Signup and view all the answers

    Which of the following is a cause of dilutional hyponatremia?

    <p>Infusion of hypotonic fluids</p> Signup and view all the answers

    What is the mechanism of nonosmotic ADH secretion?

    <p>Stress</p> Signup and view all the answers

    Which of the following is a cause of hypovolemic hyponatremia due to extrarenal losses?

    <p>Vomiting</p> Signup and view all the answers

    Which of the following is a cause of euvolemic hyponatremia due to nonosmotic ADH secretion?

    <p>Pain</p> Signup and view all the answers

    What is the difference between hypovolemic and euvolemic hyponatremia?

    <p>Total body Na+ is decreased in hypovolemic hyponatremia</p> Signup and view all the answers

    What is the primary goal of treating hypernatremia?

    <p>Replacing water</p> Signup and view all the answers

    What is the primary cause of hypernatremia, especially in the elderly?

    <p>All of the above</p> Signup and view all the answers

    Which of the following signs and symptoms is typically associated with hypernatremia?

    <p>All of the above</p> Signup and view all the answers

    What is the primary treatment for hypernatremia in patients who cannot drink?

    <p>IV fluids with D5W</p> Signup and view all the answers

    What type of hypernatremia is associated with hypovolemia?

    <p>Hypernatremia with hypovolemia</p> Signup and view all the answers

    What is the consequence of excess loss of water from the body that is not adequately replaced?

    <p>Hypernatremia</p> Signup and view all the answers

    What is a common cause of hypernatremia in the elderly?

    <p>All of the above</p> Signup and view all the answers

    What is the primary mechanism of hypernatremia in patients with diabetes insipidus?

    <p>Excess water loss due to impaired ADH secretion</p> Signup and view all the answers

    What is the effect of angiotensin II on the development of hyponatremia?

    <p>It potentiates the development of hyponatremia</p> Signup and view all the answers

    What is the difference in brain electrolyte content between acute and chronic hyponatremia?

    <p>Brain electrolyte content is lower in chronic hyponatremia</p> Signup and view all the answers

    What is the characteristic of hyponatremia with hypovolemia?

    <p>Decreased total body water and sodium</p> Signup and view all the answers

    What is the primary cause of symptoms of CNS dysfunction in acute hyponatremia?

    <p>Rapid decrease in brain electrolyte content</p> Signup and view all the answers

    What is the characteristic of hyponatremia with euvolemia?

    <p>Near normal total body sodium</p> Signup and view all the answers

    What is the effect of angiotensin on renal H2O excretion?

    <p>It decreases renal H2O excretion</p> Signup and view all the answers

    What is the difference in brain water content between acute and chronic hyponatremia?

    <p>Brain water content is higher in acute hyponatremia</p> Signup and view all the answers

    What is the characteristic of hyponatremia with hypervolemia?

    <p>Increased total body water and sodium</p> Signup and view all the answers

    What is the primary consideration for decision-making in asymptomatic patients?

    <p>Complicating problems</p> Signup and view all the answers

    What is a common symptom in the so-called asymptomatic patient?

    <p>Crying easily</p> Signup and view all the answers

    What is the exception in terms of complications in asymptomatic patients?

    <p>Nephrolithiasis</p> Signup and view all the answers

    What is the recommended approach for patients with mild symptoms and Ca+ levels below 15 mg/dL?

    <p>Conservative approach</p> Signup and view all the answers

    What is a characteristic of the so-called asymptomatic patient?

    <p>Association with psychiatric and neuromuscular disturbances</p> Signup and view all the answers

    What is the significance of Ca+ levels in the decision-making process?

    <p>Ca+ levels are irrelevant in asymptomatic patients</p> Signup and view all the answers

    What is the relationship between Ca+ levels and symptoms in asymptomatic patients?

    <p>Ca+ levels have no impact on symptoms</p> Signup and view all the answers

    What is the primary goal in managing asymptomatic patients?

    <p>Preventing complications</p> Signup and view all the answers

    What is the goal of administering IV 0.9% NS with KCL and Lasix in patients with hypercalcemia?

    <p>To expand ECF and increase renal excretion of Ca+</p> Signup and view all the answers

    What is the treatment of choice for symptomatic and progressive hyperparathyroidism?

    <p>Surgery</p> Signup and view all the answers

    What is the purpose of using 99m Tc Sestamibi in parathyroid surgery?

    <p>To 'map' the tumor prior to surgery</p> Signup and view all the answers

    What is the recommended approach when referring a patient with hyperparathyroidism for surgery?

    <p>Send the patient to a surgeon experienced in parathyroid exploration</p> Signup and view all the answers

    Which of the following is a treatment approach for mild hypercalcemia in postmenopausal women?

    <p>Estrogen therapy</p> Signup and view all the answers

    What is the recommended approach for patients with malignancy and hypercalcemia?

    <p>Bisphosphonates and NS</p> Signup and view all the answers

    What is the role of IV 0.9% NS with KCL and Lasix in treating hypercalcemia?

    <p>To expand ECF and increase renal excretion of Ca+</p> Signup and view all the answers

    What is the goal of achieving a urine output of at least 3 liters/day in patients with hypercalcemia?

    <p>To expand ECF and increase renal excretion of Ca+</p> Signup and view all the answers

    What is the primary mechanism leading to hypermagnesemia in patients with renal impairment?

    <p>Deficient excretion of magnesium in the urine</p> Signup and view all the answers

    What is the characteristic EKG finding in patients with hypermagnesemia?

    <p>Prolonged PR interval</p> Signup and view all the answers

    What is the most common cause of hypermagnesemia?

    <p>Chronic ingestion of magnesium-containing laxatives or antacids</p> Signup and view all the answers

    What is the clinical presentation of hypermagnesemia when the plasma level exceeds 12-15 mEq/L?

    <p>Respiratory depression and hypotension</p> Signup and view all the answers

    What is the indication for surgical therapy in patients with hypercalcemia?

    <p>All of the above</p> Signup and view all the answers

    What is the characteristic of decreased cortical bone density in patients with hypercalcemia?

    <p>Decreased cortical bone density</p> Signup and view all the answers

    What is the primary mechanism leading to nephrolithiasis in patients with hypercalcemia?

    <p>Increased excretion of calcium in the urine</p> Signup and view all the answers

    What is the indication for surgical therapy in patients with hypercalcemia and reduced renal function?

    <p>All of the above</p> Signup and view all the answers

    Study Notes

    Syndrome of Inappropriate Antidiuretic Hormone Secretion (SIADH)

    • ADH release is sustained despite low plasma osmolality
    • In some cases, ADH secretion is erratic and independent of osmotic control
    • In others, ADH levels vary appropriately with plasma osmolality, but the osmotic threshold for ADH is abnormally low (reset osmostat)
    • A small group of people have low levels of ADH, which is not suppressed when plasma becomes hypoosmotic

    Diagnosing SIADH

    • Symptoms of hyponatremia occur when plasma osmolality falls to 120 mmol/L
    • Causes of SIADH include:
      • Heart failure
      • Diarrhea
      • Pancreatitis
      • Postop narcotics
      • Hepatic cirrhosis
      • Renal losses
      • Diuretics
      • Hypothyroidism
      • Glucocorticoid deficiency
      • Primary polydipsia
      • Acute renal failure
      • Chronic renal failure

    Euvolemic Hyponatremia

    • Total body water (TBW) is normal, and there is no significant change to total body Na+
    • Dilutional hyponatremia can occur from excessive H2O intake without Na+ retention in presence of renal failure, Addison's disease, myxedema, or nonosmotic ADH secretion (stress, post-op, and certain drugs)

    Hypervolemic Hyponatremia

    • Increase in TBW and total body Na+ content
    • Causes include:
      • CHF and Liver Failure
      • Decrease in effective circulating volume, leading to release of ADH and angiotensin II
      • Hyponatremia results from antidiuretic effect of ADH on kidneys
      • Taking loop diuretics
      • Burns
      • Excessive sweating

    Pathogenesis of Hypernatremia

    • Usually caused by excess loss of H2O from the body that is not adequately replaced
    • Most common cause of hypernatremia from osmotic diuresis is hyperglycemia, seen in nonketotic hyperosmolar hyperglycemic coma of diabetes
    • Renal insufficiency can prevent maximally concentrated urine, predisposing to hypernatremia
    • When H2O deficit exists, hypernatremia occurs without disturbance in Na+ balance
    • Excess sweating can lead to hypernatremia

    Pathogenesis of Hypernatremia (con't)

    • Diabetes insipidus is a defect in production or release of ADH by posterior pituitary
    • Patient cannot secrete a concentrated urine
    • Thirst is normal, but patient develops hypernatremia if they do not have access to H2O

    Causes of Hypernatremia

    • Extrarenal losses:
      • Vomiting
      • Diarrhea
      • Burns
      • Excess sweating
      • Fever
      • Tachypnea
      • Hyper-tonic IV fluids
      • Hypertonic Saline
      • TPN
    • Renal losses:
      • Intrinsic renal disease
      • Osmotic diuresis
      • Loop diuretics
      • Central DI
      • Nephrogenic DI
      • Mineralocorticoid excess
      • Adrenal tumor secreting deoxycorticosterone
      • Congenital adrenal hyperplasia
      • Iatrogenic
      • Inability to access H2O
      • Primary hypodipsia
      • Reset osmostat

    Hypernatremia

    • Common in the elderly, related to inability to access H2O, impaired thirst, impaired renal concentrating ability, and increased insensible H2O loss.
    • Diagnosis: signs and symptoms include thirst, CNS symptoms (brain stem shrinkage, confusion, neuromuscular irritability, seizures, and coma).
    • Treatment: primary goal is H2O replacement, with IV D5W if the patient cannot drink.

    Principle Causes of Hypernatremia

    • Hypernatremia with hypovolemia: decreased GFR and excretion by angiotensin II, potentiating development of hyponatremia.
    • Hypernatremia with euvolemia: direct impairment of renal H2O reabsorption.
    • Hypernatremia with hypervolemia: increased total body sodium and water.

    Effects on CNS

    • Brain cellular H2O content decreases in acute and chronic hyponatremia.
    • Symptoms of CNS dysfunction are more common and greater in acute hyponatremia.

    Principle Causes of Hyponatremia

    • Hyponatremia with hypovolemia: decreased total body water and sodium, with greater relative decrease in sodium.
    • Hyponatremia with euvolemia: near normal total body sodium, with increased total body water.
    • Hyponatremia with hypervolemia: increased total body sodium, with relatively greater increase in total body water.

    Treatment of Hyponatremia

    • If symptoms are mild, Ca+ is 15 mg/dL, and conservative approach is appropriate.
    • If symptoms are severe, H2O replacement is primary goal.

    The So-Called Asymptomatic Patient

    • Most cases are associated with psychiatric and neuromuscular disturbances that are not articulated.
    • Prominent symptoms include anxiety, nervousness, daytime sleepiness, loss of energy, crying easily, excessive worry, irritability, and lack of interest.

    Therapy

    • Rate of complications is low in asymptomatic patients, except for nephrolithiasis.
    • Decision for or against surgery is based on complicating problems.
    • Mild hypercalcemia in postmenopausal women may respond to estrogens.
    • For Vitamin D excess, Prednisone 20-40 mg/day PO usually controls Ca+.

    Treatment of Hypercalcemia

    • With normal renal function: IV of 0.9% NS with KCL and Lasix to increase renal excretion of Ca+ by expanding ECF.
    • In patients with malignancy: bisphosphonates plus NS and Lasix to inhibit osteoclasts from absorbing bone.
    • If hyperparathyroidism is symptomatic and progressive: surgery is the treatment of choice.

    Surgical vs Conservative Therapy

    • Guidelines for surgery: calcium > 12 mg, hypercalciuria >400 mg/24 hrs, nephrolithiasis, cystic bone disease, overt neuromuscular disease, decreased cortical bone density, and reduced renal function.

    Hypermagnesemia

    • Etiology: rare, deficient excretion of magnesium in urine due to renal disease or renal failure, chronic ingestion of magnesium-containing laxatives or antacids.
    • Signs and symptoms: if plasma level is 5-10 mEq/L, EKG shows prolonged PR interval, widening of QRS, and increased T wave amplitude; DTRs decrease or disappear, hypotension, respiratory depression, and cardiac arrest when magnesium >12-15 mEq/L.

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    Description

    This quiz is about hyponatremia, a condition characterized by low sodium levels, and its relation to the release of Anti-Diuretic Hormone (ADH). It covers the osmotic threshold for ADH release and its suppression in certain individuals.

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