SIADH

Question 1

What is SIADH?

Answer 1

Overproduction or secretion of ADH (Anti Diuretic Hormone)
Release of ADH despite normal or low plasma osmolarity

ADH increase the permeability of the renal distal tubule and collecting duct, which leads to reabsorption of water in the circulation

Question 2

What causes SIADH? I

Etiology

Answer 2

• MOST COMMON CAUSE Small Cell Lung Cancer
• Head Trauma
• Malignant Tumors: brain
• CVA: CVA too close to pituitary gland
• Infection: Meningitis
• Metabolic d/o: Hyperglycemia, Tach- Sachs Disease

Question 3

What causes SIADH? II

Etiology

Answer 3

Drug Therapy: Carbamazepine (Tegretol), Opioids, Oxytocin, Thiazides, Tricyclics Antidepressant, SSRI, Diabinee, antineoplastic

• Systemic Lupus Erythematosus
• Hypothyroidism: Inadequate release of ADH & decreased GFR
• Lung Infections: COPD, PNA
• Guillian-Barre Syndrome

Question 4

Clinical manifestations of SIADH I

Answer 4

• Serum HypoOsmolaloty: you have more water than solutes in body. Normal 280-295.
• Dilutional Hyponatremia: Na+ < 134 . ADH holds onto water.
• Thirst: triggered thirst response because of ADH
• Fluid restriction
• Hypochloremia

Question 5

Clinical manifestations of SIADH II

Answer 5

• ⬆️ intravascular volume
• ⬇️ Na+ <120 mEq/L Normal (135-145)
• concentrated urine - ⬇️ urine output
• NORMAL renal function
• Muscle cramps, weakness, & Fatigue
• cerebral edema: 2/2 hyponatremia
• seizure, coma, lethargy: 2/2 hyponatremia

Question 6

Diagnostics for SIADH

Answer 6

• Serum osmolality: (more water, less solutes) < 280 mOsm/kg
• Serum Na+: < 134 mEq/L
• Urine osmolality: (Urine CONCENTRATED) > 100 mOsm/kg
• Urine Specific gravity: > 1.025
• ** serum osmolality lower than urine osmolality indicates inappropriate excreting concentrated urine in the presence of dilute serum***

Question 7

Pharmacological management of SIADH

Answer 7

• Treatment GOAL: restore normal fluid volume & osmolality*
• Hypertonic Saline Solution: 3-5% ( if patient <125mEq/L)
• Diuretic: Furosemide/Lasix (Patient >125 mEq/L) rid of water
• Demeclocycline, Lithium: block effects of ADH on renal tubules
• allows for a more dilated urine*
• Vasopressor Receptor Antagonist: Tolvaptan, Conivaptan: ICU med
• for euvolemic- hyponatremia. Need to be monitored*

Question 8

Management/ Interventions for SIADH

Answer 8

• Neuro assessment Q2-4 HR
• Vs, LOC, I&O, weight, SG
• Position Flat or 10 degree elevation: enhances venous return to heart & increases Left Atrial Filling pressure, reducing ADH release.
• Check ⬇️ UOP w/ ⬆️ SG, Sudden weight gain w/o edema
• Diet: Supplement Na+ & K+

Question 9

Fluid restrictions on SIADH

Answer 9

Treatment GOAL: restore normal fluid volume & osmolality
Fluid restriction
Patient has Na+ < 120 mEq/L
- 500mL/ 24 hr
Patient has Na+ > 125 mEq/L
- 800-1000mL/24 hr

Question 10

SIADH is an NonEndocrine origin
(Does not originate in endocrine system but more from outside forces)
Name those outside force.

Answer 10

⬆️ Extracellular Fluid Volume
⬇️ plasma osmolality
⬆️ GFR: as a result of extracellular water expansion induced by water retention google
⬇️ Na+ levels: due to dilution ( too much water in extracellular space)
** Hyponatremia causes muscle cramping, weakness, pain***