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SIADH Flashcards

1
Q

What does SIADH/SIAD stand for?

A
  • Syndrome of Inappropriate Secretion of Antidiuretic Hormone
    OR
  • Syndrome of Inappropriate Antidiuresis
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2
Q

What is osmolality?

A

A measure of the solute (Na, K, Cl) concentration in a unit of water.

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3
Q

What is anit-diuretic hormone (ADH)?

A
  • Also called Arginine Vasopressin.

- Produced by the hypothalamus and stored in the posterior pituitary gland.

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4
Q

What are the 2 primary functions of ADH?

A
  • Regulates water retention in Kidneys

- Vascular constriction

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5
Q

SIADH is a result from?

A
  • Hyponatremia and hypo-osmolality
  • Resulting from inappropriate, continued secretion or action of ADH despite normal or increased plasma volume, which results in impaired water excretion.
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6
Q

Hyponatremia is a result of what?

A

Hyponatremia is a result of an excess of water rather than a deficiency of sodium.

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7
Q

In general, SIADH is due to what 3 things?

A
  1. Elevated levels of ADH
    2: Water retention
    3: Loss of or dilution of certain electrolytes or solutes (Na, K, Cl)
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8
Q

What is the most important effect of ADH?

A

Conserve water by reducing water loss through the kidneys.

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9
Q

Higher ambient temperatures causes what?

A

Loss of water via sweat.

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10
Q

Increased plasma osmolarity causes what?

A

A concentration of blood solutes.

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11
Q

What is the pathophysiology of ADH (Vasopressin)?

A
  • Vasoconstrictor.
  • Synthesized in the hypothalamus .
  • Stored in the posterior pituitary.
  • Endocrine negative feedback mechanism from Osmoreceptors in hypothalamus.
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12
Q

What are the kidneys response to ADH?

A
  • ADH increases the permeability of the distal convoluted tubules in the nephrons
  • This allows for water reabsorption, thus preventing water loss.
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13
Q

ADH activity dilutes what?

A

ADH activity dilutes blood levels of solutes.

- water reabsorption NOT solute absorption.

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14
Q

What are the CNS response to ADH?

A
  • Dysarthria: Slurred or slow speech
  • Lethargy
  • Confusion
  • Delirium
  • Seizures
  • Coma(frombrain swelling)
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15
Q

Most cases of SIADH have what etiology? and what are most caused by?

A
  • Cancer etiology

- 70% are caused by Small Cell Lung CA .

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16
Q

Where are some ADH producing tumors?

A
  • Carcinomas (Small Cell)
  • Bronchogenic
  • Pancreatic
  • Prostatic
  • Duodenal
  • Colon
  • Thymoma
  • Thymus gland
  • Leukemia
  • Lymphoma
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17
Q

What are common causes of SIADH in pulmonary disease?

A
  • Asthma
  • Pneumonia
  • Tuberculosis
  • Lung Abscess
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18
Q

What are the CV responses to ADH?

A
  • ADH increases peripheral vascular resistance and thus increases arterial blood pressure.
  • Becomes an important compensatory mechanism for restoring blood pressure in various forms of hypovolemic shock
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19
Q

What are the forms of hyopvolemic shock?

A
  • Dehydration
  • Bleeding
  • Vomiting
  • Burns
  • Diuretics
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20
Q

What are common causes of SIADH in CNS disorders?

A
  • Meningitis / Encephalitis
  • CVA
  • Brain Abscess
  • Intracranial hemorrhage
  • Cerebral aneurysm
  • Subdural bleeds
  • Head trauma
  • Vascilitis: Lupus
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21
Q

What drugs cause SIADH?

A
  • Antibiotics: Ciprofloxin
  • SSRI’s: Fluoxetine (Prozac)
  • TCAs
  • Carbamazepine (Tegretol):
  • Chlorpropamide: Sulphonylurea
  • Cyclophosphamide: tx of Lymphoma
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22
Q

What level of sodium is indicative of hyponatremia?

A

<135 mEg/L

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23
Q

What are sxs of sodium <130?

A
  • Weakness
  • Weight gain
  • HA
  • Anorexia
  • Lethargy
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24
Q

What are sxs of sodium <115?

A
  • Mental status changes
  • Seizures
  • Coma
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25
Q

What are neurological sxs of SIADH?

A
  • Irritability
  • Personality changes
  • HAs
  • Combativeness
  • Confusion
  • Hallucinations
  • Seizures
  • Coma
  • Decreased Reflexes
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26
Q

What are GI sxs of SIADH?

A
  • Nausea
  • Vomiting
  • Muscle cramps
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27
Q

What are medical comorbidities of SIADH?

A
  • CHF
  • Liver failure
  • Renal failure
  • Pneumonia
28
Q

Hyponatremia is recognized only secondary to the comorbidity sxs such as what?

A
  • Dyspnea
  • Jaundice
  • Uremia
  • Cough
29
Q

The recognition of SIADH is entirely what? and pts may develop clinical sxs d/t what?

A
  • Entirely incidental.

- Sxs may be d/t the cause of hyponatremia or hyponatremia itself.

30
Q

What labs/imaging should you consider for SIADH workup?

A
  • CBC
  • CMP
  • Plasma Cortisol
  • CT of the head: Meningitis
  • CXR: SCLC
  • Radioimmunoassay of ADH
31
Q

What IV solutions should you use for tx of SIADH?

A
  • Isotonic (no shift of intra or extra cellular fluids)
  • Hypotonic (shifts fluid into cells)
  • Hypertonic (shift fluids out of cells)
32
Q

What are some Isonotic solutions?

A
  • Normal Saline (NS - 0.9% Saline)
  • Lactated Ringers (LR)
  • Dextrose and Water (D5W)
33
Q

Why should you be cautions of D5W?

A
  • The glucose quickly metabolizes in the system and becomes hypotonic solution and can complicate what you are trying to accomplish
34
Q

What are the indications of isotonic IV solution?

A
  • Volume expander
  • Dilute medications
  • To Keep vein Open (TKO)
35
Q

What are the CI of isotonic IV solution?

A

Volume overloaded patients

36
Q

What are examples of hypotonic IV solutions?

A
  • 2.5 NS
  • .33 NS
  • .45 NS
37
Q

What are the indications of hypotonic IV solution?

A

Cellular hydration

38
Q

What are the CI of hypotonic IV solution?

A
  • Hypotension (Decreased BP)

- Increased Intra Cranial Pressure (ICP)

39
Q

What are examples of hypertonic IV solutions?

A
  • D5 1/2,
  • D5 NS
  • D5 LR
40
Q

What are the indications of hypertonic IV solution?

A
  • Hypovolemia
  • Fluid expansion
  • Increased urine output
41
Q

What are the CI of hypertonic IV solution?

A
  • Renal failure

- Cardiac patients

42
Q

What is the tx for SIADH?

A
  • Treating underlying causes
  • Fluid restriction of 800-1,000 ml/day to increase serum sodium.
  • Intravenous saline
43
Q

IV saline should only be used in what type of pts?

A

Symptomatic patients: severe confusion, convulsions, or coma

44
Q

What is the Na content in D5W, 0.45% Saline, 0.9% Saline, 3% Saline?

A

D5W: 0
0.45% Saline: 77
0.9% Saline: 154
3% Saline: 513

45
Q

There are drugs used for tx in SIADH but what should we do in primary care before starting medication?

A

TURF TURF TURF

46
Q

What are causes of hyponatremia?

A
  • Vomiting
  • Diuretics
  • SIADH
  • Burns, wound drainage
  • Excessive water intake
  • Excessive administration of IV D5W
47
Q

What are causes of hypernatremia?

A
  • Hyperventilation
  • Inadequate water ingestion
  • Diabetes insipidus
  • Ingesting large amount of saltwater
  • Ingestion of OTC drugs such as Alka-Seltzer
  • Hypertonic tube feedings w/o water supplements
48
Q

What are the sxs of hyponatermia <135?

A
  • Nausea
  • Muscle cramps
  • Confusion
  • Muscular twitching
  • Headache
  • Seizures
  • Coma
49
Q

What are the sxs of hypernatermia >145?

A
  • Elevated temperature
  • Weakness
  • Disorientation
  • Irritability and restlessness
  • Thirst
  • Dry, swollen tongue
  • Sticky mucus membranes
  • HTN
  • Tachycardia
50
Q

What are the causes of hypokalemia <3.5?

A
  • Gastric Suction
  • Vomiting
  • Prolonged diarrhea
  • Diuretics and Steroids
  • Inadequate intake
51
Q

What are the causes of hyperkalemia >5.3?

A
  • Renal failure
  • Use of K+ supplements
  • Burns
  • Crushing injuries
  • Severe infection (Sepsis)
52
Q

What are the sxs of hypokalemia <3.5?

A
  • Anorexia, N/V
  • Weak peripheral pulses
  • Muscle weakness, paresthesias, decreased DTR’s
  • Impaired urine concentration
  • Ventricular dysrhythmias
  • Increased instance of digitalis toxicity
  • Shallow respirations
53
Q

What are the sxs of hyperkalemia >5.3?

A
  • EKG changes: Peaked T waves with wide QRS complexes
  • Dysrhythmias: V-Fib, CHB
  • Cardiac arrest
  • Muscle twitching and weakness
  • Numbness in hands, feet, and circum-oral
  • Nausea
  • Diarrhea
54
Q

What is Diabetes Insipidus (DI)?

A

An uncommon condition in which the kidneys are unable to prevent the excretion of water.

55
Q

Those with DI have a normal level of what?

A

Normal Glucose levels, but their kidneys are not able to balance fluid in the body.

56
Q

What are similarities of DI and DM?

A

If both are left untreated DI and DM cause constant thirst and frequent urination.

57
Q

DI is a polyuric disorder which means what?

A
  • Insufficient production of Vasopressin
    OR
  • Unresponsiveness of the renal tubules to Vasopressin
58
Q

Insufficient production of Vasopressin is known as what 2 types of DI?

A
  • Pituitary DI

- Neurogenic DI

59
Q

Unresponsiveness of the renal tubules to Vasopressin is known as what type of DI?

A

Nephrogenic DI

60
Q

What is the MC etiology of DI?

A

Meningitis

61
Q

What are some causes of Neurogenic DI?

A
  • Idiopathic
  • Head trauma
  • Meningitis
  • Neoplasm
  • MS
62
Q

What are some causes of Nephrogenic DI?

A
  • Drugs: Lithium, Aminoglycosides, Antivirals
  • Metabolic: HyperNa, HypoK
  • Sarcoidosis
  • Sickle Cell Disease
  • Low protein diets
63
Q

What are some DDx of DI?

A
  • DM
  • Polydipsia med: Thorazine (for hiccups)
  • Osmotic diuresis: glucose, mannitol
  • Psych polypisia: electrolyte disturbances
64
Q

What are some PE and clinical presentations of DI?

A
  • Abrupt onset
  • Nocturia
  • Polyuria: 2.5 – 6 Liters / Day
  • Polydipsia
  • Neurologic manifestations: Seizures, HA, visual field defects
65
Q

What is the primary work up of DI?

A

Showing the polyuria is caused by the inability to concentrate urine resulting in:

  • decreased vasopressin production or
  • insensitivity to vasopressin
66
Q

What is the basic treatment of DI?

A

Endocrinology consultation for diagnostic testing, referral, and structured treatment plan.

Endocrinology (18 decks)

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