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?

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

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

Reset osmostat Signup and view all the answers

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

Dilutional hyponatremia Signup and view all the answers

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

Nonosmotic ADH secretion Signup and view all the answers

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

Hypervolemic hyponatremia Signup and view all the answers

What is the primary cause of Hypovolemic Hyponatremia?

Renal losses Signup and view all the answers

Which of the following is a characteristic of Euvolemic Hyponatremia?

Normal blood volume Signup and view all the answers

What is the primary mechanism of Hypervolemic Hyponatremia?

Water retention due to increased ADH secretion Signup and view all the answers

What is the primary cause of Dilutional Hyponatremia?

Excessive free water intake Signup and view all the answers

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

Emotional stress Signup and view all the answers

Which of the following is a cause of Euvolemic Hyponatremia?

SIADH Signup and view all the answers

What is the primary mechanism of SIADH?

Sustained ADH secretion Signup and view all the answers

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

Heart failure Signup and view all the answers

What is the primary cause of hypovolemic hyponatremia?

Severe diarrhea and vomiting leading to sodium loss Signup and view all the answers

What is the characteristic of euvolemic hyponatremia?

No significant change in total body sodium content Signup and view all the answers

What is the primary cause of dilutional hyponatremia?

Increased water intake without sodium retention Signup and view all the answers

What is the characteristic of hypervolemic hyponatremia?

Increased total body water and sodium content Signup and view all the answers

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

Chlorpropamide Signup and view all the answers

What is the role of ADH in hypervolemic hyponatremia?

It increases water reabsorption in the kidneys Signup and view all the answers

What is the common feature of hypovolemic and hypervolemic hyponatremia?

Release of ADH Signup and view all the answers

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

Decreased aldosterone secretion 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?

Approche conservative: Signup and view all the answers

Qual es le characteristicas de un paciente con symptomas leve?

Tutte le optiones supra: Signup and view all the answers

Quale es le complication major in patientes asymptomatic?

Nephrolithiasis: Signup and view all the answers

Quando debe on decidir contra o pro le chirurgia?

Quando le patiente presenta complicaciones: Signup and view all the answers

Quale es le approche conservative in patientes asymptomatic?

Observation e monitorage: Signup and view all the answers

Qual es le caracteristica de un patiente asymptomatic?

Non presenta symptomas: Signup and view all the answers

Quando debe on considerar le chirurgia?

Quando le patiente presenta complicaciones: Signup and view all the answers

Quale es le objectivo del tractamento in patientes asymptomatic?

Prevenir complicaciones: Signup and view all the answers

Qual es le indication de hyperparathyroidismo primari?

Serum Ca++ alto, PO4- normal Signup and view all the answers

Qual es le diagnose de Humoral Hypercalcemia de Malignancy?

PTH-related peptide Signup and view all the answers

Qual es le characteristica de benign familial hypercalcemia?

No hypercalciuria e no complications de hypercalcemia Signup and view all the answers

Quando debe esser executate le diagnose de hypercalcemia?

When serum Ca++ is high Signup and view all the answers

Qual es le role de alkaline phosphatase in hyperparathyroidismo?

Indicar bone turnover Signup and view all the answers

Quale es le causa principal de hyponatremia hypovolemica?

Perdita de fluidos extrarenal Signup and view all the answers

Qual es le assay utilisate pro diagnosticar hyperparathyroidismo?

PTH by IRMA Signup and view all the answers

Quale es le caracteristica de hyponatremia euvolemica?

Normal o aumentate volumine de fluidos Signup and view all the answers

Quale es le complication de hypercalcemia?

All of the above Signup and view all the answers

Quale es le mechanismo principal de hyponatremia hypervolemica?

Aumentate de fluids con diminution de osmolalitate Signup and view all the answers

Qual es le caratteristica de hyperparathyroidismo?

Low PO4- and high serum Ca++ Signup and view all the answers

Quale es le causa de hyponatremia dilutional?

Infusion de fluidos hypotonic Signup and view all the answers

Quale es le effecto de ADH in hyponatremia hypervolemica?

Diminui la osmolalitate Signup and view all the answers

Quale es le caratteristica de hyponatremia SIADH?

Secregation erratic de ADH Signup and view all the answers

Quale es le causa de hyponatremia in syndrome de Cushing?

Excesso de-secretion de corticoides Signup and view all the answers

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

Diminui la osmolalitate Signup and view all the answers

Quale es le caracteristica del SIADH?

Urinas dilute in le presentia de plasma hypeosmolality Signup and view all the answers

Quale es le causa del hypovolemic hyponatremia?

Perdita de liquido corporal Signup and view all the answers

Quale es le mechanismo principal del SIADH?

Sustained ADH secretion Signup and view all the answers

Quale es le characteristic del hypervolemic hyponatremia?

Excesso de liquido corporal Signup and view all the answers

Quale es le causa del euvolemic hyponatremia?

Sustained ADH secretion Signup and view all the answers

Quale es le rolo de ADH in le hypervolemic hyponatremia?

Regula le concentartion de sodio in le plasma Signup and view all the answers

Quale es le causa del dilutional hyponatremia?

Infundimento de liquido hypotonic Signup and view all the answers

Quale es le caracteristica del nephrotic syndrome?

Perdita de proteina in le urina Signup and view all the answers

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

Hypercalciuria > 400 mg/24 hrs Signup and view all the answers

Quales es le effecto del magnesium sur le systema nervose?

Decresce le reflexos Signup and view all the answers

Quales es le causa plus commun de hypermagnesemia?

Ingere chronica de laxativos o antacidos Signup and view all the answers

Quales es le manifestation clinic plus commun de hypermagnesemia?

Hypotension Signup and view all the answers

Quales es le nivel de magnesium que causa cardiac arresto?

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

Quales es le effecto del magnesium sur le EKG?

Prolonga le intervallo PR Signup and view all the answers

Quales es le tratamento de election pro hypermagnesemia?

Administrar calcium gluconate Signup and view all the answers

Quales es le complication plus grav de hypermagnesemia?

Cardiac arresto 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.