SIADH is a disorder of impaired water excretion caused by the inability to suppress the secretion of antidiuretic hormone (ADH). Inappropriate, continued secretion or action of ADH despite normal or increased plasma volume. Results in impaired water excretion, and subsequently hyponatremia and hypo-osmolality.

1. Syndrome of inappropriate
antidiuretic hormone secretion
(SIADH)
Presented By,
Miss. Silla Elsa Soji
MSc Nursing
TMM College of Nursing

2. DEFINITION
SIADH is a disorder of impaired water excretion caused
by the inability to suppress the secretion of antidiuretic
hormone (ADH). Inappropriate, continued secretion or
action of ADH despite normal or increased plasma
volume. Results in impaired water excretion, and
subsequently hyponatremia and hypo-osmolality.

4. PATHOPHYSIOLOGY

6. CLINICAL MANIFESTATION
• Weight gain and decreased urine output
• Initially anorexia, thirst, dyspnea on exertion,
headaches, nausea and vomiting
• Later confusion, irritability, seizure and coma from
severe hyponatremia
• Gastro-intestinal- Anorexia, Nausea, vomiting
• Musculoskeletal- Muscle aches, Generalized muscle
weakness

7. • Neuromuscular- Decreased reflexes, Ataxia,
instability of gait and falls
• Pathological reflexes- Tremor, Asterixis
• Respiratory- Cheyne-Stokes respiration, respiratory
insufficiency
• Neurological- Dysarthria, Lethargy, poor
concentration, Confusion, Delirium, Seizures, Coma
(from brain swelling), Death.

8. DIAGNOSTIC FINDINGS
1.History collection :
• Present health history, Chief complaints, onset,
duration, acute or chronic, etc.
• Past health history- Any malignancy, surgery,
HIV infection, pulmonary disease, etc.
• Medication history- Chemotherapy, anti-
depressants, diuretics, etc.
• Family history of SIADH

9. 2.Physical examination- Anorexia, Nausea,
Decreased reflexes, Ataxia, Tremor, Asterixis,
etc.

10. 3. Lab investigations:
• Schwartz and Bartter Clinical Criterion
• Serum sodium less than 135mEq/L
• Serum osmolality less than 275 mOsm/kg
• Urine sodium greater than 40 mEq/L (due to
ADH-mediated free water absorption from renal
collecting tubules)
• Urine osmolality greater than 100 mOsm/kg
• Plasma uric acid <4 mg/dl.
• Blood urea nitrogen <10 mg/dl.

11. • The absence of clinical evidence of volume depletion
- normal skin turgor, blood pressure within the
reference range
• The absence of other causes of hyponatremia -
adrenal insufficiency, hypothyroidism, cardiac
failure, pituitary insufficiency, renal disease with
salt wastage, hepatic disease, drugs that impair
renal water excretion.
• Correction of hyponatremia by fluid restriction
• Renal function tests and random blood sugar test
should be done to check hyperglycaemia and uraemia
as these are the potential causes of
pseudohyponatremia.

12. MEDICAL
MANAGEMENT

13. Principles of treatment of hyponatremia Treatment
depends on:
• Volume status
• Duration of hyponatremia (whether acute/<48 h
or chronic >48 h))
• Presence or absence of symptoms
• Etiology of hyponatremia.

14. Goals:
• Looking for the cause if possible
• Measure the liquid electrolyte is not balanced
• Prevent complications

15. Pharmacological management:
• Hypertonic IV fluids to correct hyponatremia
• Sodium restriction
• Diuretics to correct low plasma osmolality
• Monitor urine electrolyte loss
• Replace electrolyte loss
• Demeclocycline to facilitate free water clearance
• Conivaptan – an antagonist of both V1A and
V2 vasopressin receptors
• Tolvaptan – an antagonist of the V2
vasopressin receptor

16. Mild asymptomatic hyponatremia
(serum Na>125mEq/L):
• Fluid restriction is the 1st line treatment.
• It generally improves with correction of
underlying cause and restriction of free fluid
intake to 800-1000 ml/d.
• If no response, fluid intake can be restricted to
500-600 ml/d.

17. Mild symptomatic hyponatremia:
• Fluid restriction.
• Loop diuretic- it interferes with the action of
ADH in collecting tubules by inhibiting free
water reabsorption.
• The osmolality of infused saline must exceed
the osmolality of patient’s urine.

18. Severe symptomatic hyponatremia
(serum Na <125 mEq/L):
• Fluid restriction.
• Hypertonic saline- infused via pump and urine
osmolality can be followed to guide therapy.
• Hypertonic saline can be switched to isotonic
saline when urine osmolality is <300 mOsm/L.

19. NURSING DIAGNOSIS
• Excess fluid volume related to excessive amount of
antidiuretic hormone secretion as manifested by
edema, decreased urine output, etc.
• Imbalanced nutrition less than body requirements
related to nausea, vomiting and anorexia as
manifested by low serum sodium level.
• Hypothermia related to fluid overload as evidenced
by body temperature below normal range, cool, pale
skin, etc.

20. • Disturbed thought processes related to
decreased levels of sodium as manifested by
declining levels of consciousness, fatigue,
depression, etc. 5.Risk for injury related to
occurrence of seizures, coma, etc.