Siadh (1)

Syndrome of inappropriate anti-diuretic hormone secretion

1. SIADH AND ITS MANAGEMENT -BY SHWETA SHARMA M.SC. NURSING I st YEAR

2. Syndrome of inappropriate antidiuretic hormone secretion (SIADH) is also known as Schwartz-Bartter syndrome , syndrome of inappropriate antidiuresis (SIAD). SIADH is a condition in which the body makes too much antidiuretic hormone (ADH). This hormone helps the kidneys control the amount of water your body loses through the urine. SIADH causes the body to retain too much water. The resulting impairment of water secretion and consequent water retention produces the hyponatremia (i.e., serum Na+ < 135 mmol/L) with concomitant hypo-osmolality (serum osmolality < 280 mOsm /kg) and high urine osmolality that are the hallmark of SIADH.

3. EPIDEMIOLOGY OF SIADH • Most common electrolyte disorder. • Affects 15-30% of hospitalised patients. • Affects 7% of ambulatory patients. • Causes 1 million hospitalisations per year. • The incidence of SIADH increases with age. • Children and older adults are found to be more hyponatraemic , particularly when they were hospitalized for respiratory and CNS infections like pneumonia or meningitis. • SIADH is also more prevalent is hospitalized, post-operative patients due to the administration of hypotonic fluids, drugs, and the body's response to stress.

4. ROLE OF LIMBIC SYSTEM IN SODIUM AND WATER BALANCE The limbic system consists of hippocampus, amygdala, anterior thalamic nuclei, septum, limbic cortex and fornix. It is an interconnected complex and its control center is hypothalamus. Limbic system controls behaviour as well as many internal functions including osmolality of body fluids. Limbic system activation by stimuli like pain, nausea, fear, major trauma and surgery leads to increase in ADH production.

5. ETIOLOGY DRUGS - ‘CAR DISH’ • C hemotherapy • A ntidepressants, antipsychotics, anticonvulsants, anti-inflammatory drugs (cyclooxygenase-2 inhibitors) • R ecreational drugs (e.g. ecstasy) • D iuretics • I nhibitors – angiotensin converting enzyme inhibitors, selective serotonin reuptake inhibitors • S ulfonylureas • H ormones (e.g. desmopressin, oxytocin), hypnotics (e.g. temazepam)

6. Central nervous system disturbances Malignancies Pulmonary disease Surgery Hormone administration Hereditary syndrome of inappropriate antidiuretic hormone secretion- HIV infection Idiopathic

7. PATHOPHYSIOLOGY

8. SIGN AND SYMPTOMS SYSTEMIC SYMPTOMS Gastro-intestinal- Anorexia, Nausea, vomiting Musculoskeletal- Muscle aches, Generalized muscle weakness Neuro-muscular- Myoclonus, 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.

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

10. 3. Lab investigations- The 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. • The absence of clinical evidence of volume depletion - normal skin turgor, blood pressure within the reference range

11. 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 hyperglycemia and uremia as these are the potential causes of pseudohyponatremia.

12. CEREBRAL SALT WASTING SYNDROME Rare syndrome seen in patients with cerebral tumours, subarachnoid haemorrhage, patients who have undergone trans-sphenoidal pituitary surgery. Mimics SIADH i.e. hyponatremia, increased urine osmolality, urine Na > 20 mEq /l and urine osmolality > serum osmolality. It represents appropriate water resorption with salt wasting and a secondarily hypovolemic state.

13. TREATMENT 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. Management objectives in SIADH are: Looking for the cause if possible Measure the liquid electrolyte is not balanced Prevent complications

15. Medical 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 • Treat underlying cause

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 ASSESSMENT SUBJECTIVE DATA: OBJECTIVE DATA: • Nausea • Muscle cramps • Depression, irritability • Fatigue • Vomiting • Hypothermia • Tremors • Confusion • Seizures • Coma • Edema

20. NURSING DIAGNOSIS 1.Excess fluid volume related to excessive amount of antidiuretic hormone secretion as manifested by edema, decreased urine output, etc. 2.Imbalanced nutrition less than body requirements related to nausea, vomiting and anorexia as manifested by low serum sodium level. 3.Hypothermia related to fluid overload as evidenced by body temperature below normal range, cool, pale skin, etc.

21. 4.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.

22. COMPLICATIONS • Seizures • Coma • Permanent brain damage • Hyperuricemia • Fluid overload • Decrease in chloride levels (plasma or serum) • Decrease in osmolarity (plasma) • Hypokalaemia • Hypomagnesemia • Increased levels of sodium (urine) • Disease process already in progress may be complicated

23. RESEARCH ARTICLES Clinical Profile of Patients Admitted with Hyponatremia in the Medical Intensive Care Unit. A 1-year prospective cross-sectional observational study was conducted, including 100 adult patients with moderate-to-severe hyponatremia admitted to the Medical ICU. Patients underwent investigations such as serum creatinine, blood urea nitrogen, serum osmolality, serum sodium, urine sodium, and urine osmolality, sputum culture, cerebrospinal fluid analysis, and neuroimaging. Data were analysed using independent sample t-test, Chi-square test, and Fisher's exact test. Vomiting (28) followed by confusion (26) was the most common complaint. Syndrome of inappropriate antidiuretic hormone secretion (SIADH) (46) was the most common etiology for hyponatremia, and euvolemic hypoosmolar hyponatremia (50) was the most common type of hyponatremia. Confusion was significantly high in patients with severe hyponatremia as compared to patients with moderate hyponatremia (22 vs. 4, P < 0.001). In majority of the patients (46), SIADH was the main cause of euvolemic type of hyponatremia (P < 0.001). Increased urine sodium levels were observed in patients with SIADH (46), renal dysfunction (12), and drug-induced etiology (8, P < 0.001).

24. A descriptive study of hyponatremia in a tertiary care hospital of Eastern India- A descriptive study of hyponatremia was conducted in the medical ward of a tertiary care hospital from March 2010 to April 2011. All patients underwent routine hemogram , blood biochemistry, serum electrolytes, thyroid function tests, and morning serum cortisol estimation. This was followed by a plasma and urinary osmolality determination as well as urinary sodium estimation. Patients were diagnosed to have syndrome of inappropriate antidiuretic hormone secretion (SIADH) if they satisfied the Bartter and Schwartz criteria. 201 patients (16.4%) had a serum Na < 135 meq /l. There were 126 (62.69%) male patients and 75 (37.31%) female patients. Severe hyponatremia (Na < 120 meq /l) was detected in 30 patients (2.4%). The largest group of hyponatraemic patients were euvolemic [102 (50.74%)], followed by hypervolemic [54 (26.86%)] and hypovolemic [45 (22.4%)]. Sixty-six patients fulfilled the criteria for SIADH. The most common underlying predisposing factor for hyponatremia in our case series was fluid loss by vomiting/ diarrhoea . During the hospital stay, 13.5% (15/201) hyponatraemic patients died, while the corresponding figure in normo-natremic patients was 8.5% (87/1020).

25. CONCLUSION • As discussed throughout the presentation, learning about SIADH and its management will help nurses to care for a SIADH patient. • Nurses can do assessment of SIADH patient, observe the sign and symptoms, provide the necessary nursing care and support the patient psychologically. • Nurses can also counsel the patients and their family for various options available in SIADH treatment.

26. REFERENCES 1. Medscape. Syndrome of Inappropriate Antidiuretic Hormone Secretion (SIADH). Available from https://emedicine.medscape.com/article/246650-overview [cited 30 aug 2019] 2. Muhammad Yasir ; Oren Mechanic. Syndrome of Inappropriate Antidiuretic Hormone Secretion (SIADH). Available from https://www.ncbi.nlm.nih.gov/books/NBK507777/ [cited 30 aug 2019] 3. Indian Journal of Endocrinology and Metabolism. Syndrome of inappropriate antidiuretic hormone secretion: Revisiting a classical endocrine disorder. Available from http://www.ijem.in/article.asp?issn=2230-8210;year=2011;volume=15;issue=7;spage=208;epage=215;aulast=Pillai [cited 30 aug 2019] 4. Indian Journal of Endocrinology and Metabolism. Syndrome of inappropriate antidiuretic hormone secretion: Revisiting a classical endocrine disorder. Available from https://www.ncbi.nlm.nih.gov/pmc/articles/PMC3183532/ [cited 30 aug 2019]

27. 5. Joyce M. Black, Jane Hokanson Hawks. Medical Surgical Nursing Clinical Management of positive outcomes.2015. New Delhi. Reed Elsevier India Private Limited. Volume II. Pg. no. 1059,1060. 6. Lewis. Medical Surgical Nursing Assessment and Management of clinical problems.2015. New Delhi. Elsevier. 2nd Edition. Volume I. Pg. no. 1244-1246 7. Babaliche P, Madnani S, Kamat S. PubMed. Clinical Profile of Patients Admitted with Hyponatremia in the Medical Intensive Care Unit. Available from https://www.ncbi.nlm.nih.gov/pubmed/29307961 [cited 1 sep 2019] 8. Indian Journal of Endocrinology and Metabolism. A descriptive study of hyponatremia in a tertiary care hospital of Eastern India. Available from https://www.ncbi.nlm.nih.gov/pmc/articles/PMC3313751/ [cited 1 sep 2019]

28. RECAPITULATION WHAT IS SIADH??? CAUSES OF SIADH??? TYPES OF HYPONATREMIA??? NURSING DIAGNOSIS??? COMPLICATIONS???