Hyponatremia and ADH Release
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Questions and Answers

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

  • Normally high
  • Absent
  • Variable depending on ionized Ca+ levels
  • Subnormally low (correct)

    • In which type of hyponatremia does ADH secretion occur erratically and independently of osmotic control?

  • Hypervolemic hyponatremia
  • Euvolemic hyponatremia
  • Hypovolemic hyponatremia
  • SIADH (correct)

    • What is the plasma osmolality level at which symptoms of hyponatremia typically occur?

  • 20 mg/dL
  • 10 mg/dL
  • 15 mg/dL
  • 12 mg/dL (correct)

    • Which of the following is a characteristic of a small group of individuals with SIADH?

    <p>ADH is not suppressed in the presence of low plasma osmolality</p> Signup and view all the answers

    What is the term for the abnormal regulation of ADH secretion in response to changes in plasma osmolality?

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

    Which type of hyponatremia is characterized by a decrease in effective osmolality due to excessive water intake?

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

    What is the term for ADH secretion that is not stimulated by changes in plasma osmolality?

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

    Which type of hyponatremia is characterized by a decrease in effective osmolality due to excessive fluid accumulation?

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

    What is the primary cause of Hypovolemic Hyponatremia?

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

    Which of the following is a characteristic of Euvolemic Hyponatremia?

    <p>Normal blood volume</p> Signup and view all the answers

    What is the primary mechanism of Hypervolemic Hyponatremia?

    <p>Water retention due to increased ADH secretion</p> Signup and view all the answers

    What is the primary cause of Dilutional Hyponatremia?

    <p>Excessive free water intake</p> Signup and view all the answers

    What is the primary stimulus for Non-osmotic ADH secretion?

    <p>Emotional stress</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 primary mechanism of SIADH?

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

    Which of the following is a common cause of Hypervolemic Hyponatremia?

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

    What is the primary cause of hypovolemic hyponatremia?

    <p>Severe diarrhea and vomiting leading to sodium loss</p> Signup and view all the answers

    What is the characteristic of euvolemic hyponatremia?

    <p>No significant change in total body sodium content</p> Signup and view all the answers

    What is the primary cause of dilutional hyponatremia?

    <p>Increased water intake without sodium retention</p> Signup and view all the answers

    What is the characteristic of hypervolemic hyponatremia?

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

    Which of the following drugs is associated with nonosmotic ADH secretion?

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

    What is the role of ADH in hypervolemic hyponatremia?

    <p>It increases water reabsorption in the kidneys</p> Signup and view all the answers

    What is the common feature of hypovolemic and hypervolemic hyponatremia?

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

    What is the underlying mechanism of hyponatremia in Addison's disease?

    <p>Decreased aldosterone secretion</p> Signup and view all the answers

    Quando le symptomas es leve e le nivel de Ca+ es 15 mg/dL, qual es le approche adequate?

    <p>Approche conservative:</p> Signup and view all the answers

    Qual es le characteristicas de un paciente con symptomas leve?

    <p>Tutte le optiones supra:</p> Signup and view all the answers

    Quale es le complication major in patientes asymptomatic?

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

    Quando debe on decidir contra o pro le chirurgia?

    <p>Quando le patiente presenta complicaciones:</p> Signup and view all the answers

    Quale es le approche conservative in patientes asymptomatic?

    <p>Observation e monitorage:</p> Signup and view all the answers

    Qual es le caracteristica de un patiente asymptomatic?

    <p>Non presenta symptomas:</p> Signup and view all the answers

    Quando debe on considerar le chirurgia?

    <p>Quando le patiente presenta complicaciones:</p> Signup and view all the answers

    Quale es le objectivo del tractamento in patientes asymptomatic?

    <p>Prevenir complicaciones:</p> Signup and view all the answers

    Qual es le indication de hyperparathyroidismo primari?

    <p>Serum Ca++ alto, PO4- normal</p> Signup and view all the answers

    Qual es le diagnose de Humoral Hypercalcemia de Malignancy?

    <p>PTH-related peptide</p> Signup and view all the answers

    Qual es le characteristica de benign familial hypercalcemia?

    <p>No hypercalciuria e no complications de hypercalcemia</p> Signup and view all the answers

    Quando debe esser executate le diagnose de hypercalcemia?

    <p>When serum Ca++ is high</p> Signup and view all the answers

    Qual es le role de alkaline phosphatase in hyperparathyroidismo?

    <p>Indicar bone turnover</p> Signup and view all the answers

    Quale es le causa principal de hyponatremia hypovolemica?

    <p>Perdita de fluidos extrarenal</p> Signup and view all the answers

    Qual es le assay utilisate pro diagnosticar hyperparathyroidismo?

    <p>PTH by IRMA</p> Signup and view all the answers

    Quale es le caracteristica de hyponatremia euvolemica?

    <p>Normal o aumentate volumine de fluidos</p> Signup and view all the answers

    Quale es le complication de hypercalcemia?

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

    Quale es le mechanismo principal de hyponatremia hypervolemica?

    <p>Aumentate de fluids con diminution de osmolalitate</p> Signup and view all the answers

    Qual es le caratteristica de hyperparathyroidismo?

    <p>Low PO4- and high serum Ca++</p> Signup and view all the answers

    Quale es le causa de hyponatremia dilutional?

    <p>Infusion de fluidos hypotonic</p> Signup and view all the answers

    Quale es le effecto de ADH in hyponatremia hypervolemica?

    <p>Diminui la osmolalitate</p> Signup and view all the answers

    Quale es le caratteristica de hyponatremia SIADH?

    <p>Secregation erratic de ADH</p> Signup and view all the answers

    Quale es le causa de hyponatremia in syndrome de Cushing?

    <p>Excesso de-secretion de corticoides</p> Signup and view all the answers

    Quale es le effecto de diuretic-os de loop in hyponatremia?

    <p>Diminui la osmolalitate</p> Signup and view all the answers

    Quale es le caracteristica del SIADH?

    <p>Urinas dilute in le presentia de plasma hypeosmolality</p> Signup and view all the answers

    Quale es le causa del hypovolemic hyponatremia?

    <p>Perdita de liquido corporal</p> Signup and view all the answers

    Quale es le mechanismo principal del SIADH?

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

    Quale es le characteristic del hypervolemic hyponatremia?

    <p>Excesso de liquido corporal</p> Signup and view all the answers

    Quale es le causa del euvolemic hyponatremia?

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

    Quale es le rolo de ADH in le hypervolemic hyponatremia?

    <p>Regula le concentartion de sodio in le plasma</p> Signup and view all the answers

    Quale es le causa del dilutional hyponatremia?

    <p>Infundimento de liquido hypotonic</p> Signup and view all the answers

    Quale es le caracteristica del nephrotic syndrome?

    <p>Perdita de proteina in le urina</p> Signup and view all the answers

    Quales dels sequentes es un indication pro therapia surgical in un patient con hyperparathyroidismo?

    <p>Hypercalciuria &gt; 400 mg/24 hrs</p> Signup and view all the answers

    Quales es le effecto del magnesium sur le systema nervose?

    <p>Decresce le reflexos</p> Signup and view all the answers

    Quales es le causa plus commun de hypermagnesemia?

    <p>Ingere chronica de laxativos o antacidos</p> Signup and view all the answers

    Quales es le manifestation clinic plus commun de hypermagnesemia?

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

    Quales es le nivel de magnesium que causa cardiac arresto?

    <p>12-15 mEq/L</p> Signup and view all the answers

    Quales es le effecto del magnesium sur le EKG?

    <p>Prolonga le intervallo PR</p> Signup and view all the answers

    Quales es le tratamento de election pro hypermagnesemia?

    <p>Administrar calcium gluconate</p> Signup and view all the answers

    Quales es le complication plus grav de hypermagnesemia?

    <p>Cardiac arresto</p> Signup and view all the answers

    Study Notes

    SIADH Pathogenesis

    • SIADH is characterized by sustained ADH release, which can be erratic and independent of osmotic control in some individuals.
    • In others, ADH levels vary appropriately with plasma osmolality, but the osmotic threshold for ADH release is abnormally low (reset osmostat).
    • A small group of people have low levels of ADH, and when plasma becomes hypoosmotic, ADH is not suppressed.

    Diagnosing SIADH

    • Symptoms of hyponatremia occur when plasma osmolality falls to 120 mmol/dL.
    • Ionized calcium levels are almost equal to heart failure.
    • Causes of SIADH include:
      • Central nervous system disorders
      • Pulmonary disorders
      • Cancer
      • Infections
      • Pain
      • Emotional stress
      • Postoperative state
      • Narcotics
      • Hepatic cirrhosis
      • Renal disorders
      • Nephrotic syndrome
      • Acute renal failure
      • Chronic renal failure
      • Hypothyroidism
      • Glucocorticoid deficiency
      • Primary polydipsia
      • Diuretics
      • Osmotic diuresis (glucose, urea, mannitol)
      • Mineralocorticoid deficiency
      • Salt-losing nephropathies

    Syndrome of Inappropriate Antidiuretic Hormone Secretion (SIADH)

    • SIADH is characterized by less than maximally dilute urine in the presence of plasma hypoosmolality.
    • The etiology of SIADH is often unknown, but it involves sustained ADH secretion.

    Hyponatremia

    • Hyponatremia occurs when plasma sodium levels drop below 135 mmol/L.
    • Causes of hyponatremia include:
      • Protracted vomiting
      • Severe diarrhea
      • Sequestration of fluid in the 3rd space replaced with free H2O or treated with hypovolemic IVF
      • Significant ECF loss resulting in ADH release, causing H2O retention by kidneys and hyponatremia

    Euvolemic Hyponatremia

    • Euvolemic hyponatremia occurs when total body water (TBW) is increased, but there is no significant change in total body sodium content.
    • Causes of euvolemic hyponatremia include:
      • Dilutional hyponatremia due to increased H2O intake without Na+ retention in renal failure, Addison's disease, myxedema, or non-osmotic ADH secretion (stress, post-op, and certain drugs)
      • Certain medications, such as:
        • Chlorpropamide
        • Tolbutamide
        • Opioids
        • Barbiturates
        • Vincristine
        • Clofibrate
        • Carbamazepine

    Hypervolemic Hyponatremia

    • Hypervolemic hyponatremia occurs when total body water (TBW) and total body sodium content are increased.
    • Causes of hypervolemic hyponatremia include:
      • Congestive heart failure (CHF)
      • Liver failure
      • Decrease in effective circulating volume causing release of ADH and angiotensin II, leading to hyponatremia.

    Na+ Regulation and Imbalance

    • Na+ regulation occurs through renal and extrarenal mechanisms
    • Normal Na+ levels in the body (TBW) can be affected by various factors, including extrarenal losses (vomiting, diarrhea, burns, excessive sweating), renal losses (intrinsic renal disease, osmotic diuresis, loop diuretics), and hyper-tonic IV fluids

    Causes of Hyponatremia

    • Extrarenal losses: vomiting, diarrhea, burns, excessive sweating
    • Renal losses: intrinsic renal disease, osmotic diuresis, loop diuretics
    • Heart failure, pancreatitis, peritonitis, small bowel obstruction, rhabdomyolysis, burns
    • SIADH (Syndrome of Inappropriate Antidiuretic Hormone Secretion), hypothyroidism, glucocorticoid deficiency, primary polydipsia, salt-losing nephropathies

    SIADH

    • Characterized by less than maximally dilute urine in the presence of plasma hypoosmolality
    • Often caused by unknown factors
    • Low PO4- levels may indicate hyperparathyroidism

    Hyperparathyroidism

    • Primary hyperparathyroidism: increased serum Ca+, normal PO4- levels
    • Secondary hyperparathyroidism: increased serum Ca+, decreased PO4- levels
    • Humoral Hypercalcemia of Malignancy: diagnosed by presence of PTH-related peptide
    • Alkaline phosphatase levels are increased in hyperparathyroidism with increased bone turnover

    Diagnostic Tests for Hyperparathyroidism

    • Parathyroid Hormone Assays (PTH) by IRMA (immunoradiometric assays) for improved sensitivity
    • Rule out malignancy and impaired renal status
    • Check urinary excretion of calcium
    • Benign familial hypercalcemia from parathyroid hyperplasia does not have hypercalciuria or other complications of hypercalcemia

    Treatment of Hyperparathyroidism

    • Mild symptoms and Ca+ levels < 15 mg/dL: conservative approach
    • Asymptomatic patients: conservative approach, but watch for psychiatric and neuromuscular disturbances
    • Prominent symptoms: anxiety, nervousness, daytime sleepiness, loss of energy, crying easily, excessive worry, irritability, lack of interest
    • Surgical vs conservative therapy: based on complicating problems, such as nephrolithiasis, cystic bone disease, overt neuromuscular disease, decreased cortical bone density, and reduced renal function

    Hypermagnesemia

    • Rare, often due to deficient excretion of magnesium in urine (renal disease or failure) or chronic ingestion of laxatives or antacids
    • Signs and symptoms: EKG shows prolonged PR interval, widening of QRS, and increased T wave amplitude if plasma level is 5-10 mEq/L; 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 where the sodium levels in the blood are too low, and how it affects the release of antidiuretic hormone (ADH) in the body.

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