Syndrome of Inappropriate Antidiuretic Hormone (SIADH)

By Elyse NavarroNur 426

Nov. 2, 2011Glenda Tali

OVERVIEW o Case Study

o Description of Disease/Disorder

o Pathophysiology

o Clinical manifestations

o Diagnostic Tests

o Risk Factors

o Health Promotions

o Resources

SIADHSIADH

SIADH

SIADH

CASE STUDY A 66-year-old man presents to ER with symptoms of confusion, unsteadiness and headaches.

Previous history of psoriasis and frequent respiratory tract infections (two to three per year), which often required antibiotic treatment, but for which no formal diagnosis had been made.

He had a 30 pack year smoking history. He did not use medication. Based on his symptoms, his general practitioner suspected a brain tumor or early-onset dementia. His blood pressure was 126/80 lying and 130/84 standing, with a regular pulse of 88 bpm. He had no edema and his jugular venous pressure was normal.

Further physical examination was unremarkable.

SIADH

Van Der Lubbe, N., Thompson, C., Zietse, R., and Hoorn, E., The clinical challenge of SIADH—three cases NDT Plus (2009)

ANTIDIURETIC HORMONE (ADH) (ADH) SIADH

ANTIDIURETIC HORMONE (ADH)

SIADHADH FEEDBACK

SYSTEM

DESCRIPTION

• Body secretes excessive ADH• Failure in neg feedback

mechanism• Can not regulate release and

inhibition of ADH

• Potentially life threatening• Prognosis

• Depends on underlying D/O• Response to treatment

SIADH

PATHOPHYSIOLOGYExcessive antidiuretic hormone secretion

Increased renal tubule permeability

Increased water retention & expanded extracellular fluid volume

Reduced Plasma

osmolality

IntracellularFluid shift

Cerebraledema

Dilutionalhyponatremia

Diminishedaldosterone

secretion

Decreasedsodium

reabsorption in proximal

tubule

IncreasedSodium

excretion

Hyponatremia

Elevatedglomerular

filtration rate

SIADH

CLINICAL MANIFESTATIONS• CNS: weakness, lethargy, mental confusion, difficulty concentrating, restlessness, HA, seizures and coma

• GI: Congestion of GI tract & motility N/V, anorexia, muscle cramps, and bowel sounds

• CVS: Weight gain, Bp, elevated central venous & pulmonary artery occlusion pressure

• Pulmonary System: Fluid overload respirations, dyspnea, adventitious lung sounds, and frothy pink sputum

****Sx usually caused by hyponatremia & fluid retention

SIADHEarly signs and symptoms associated with mild to moderate hyponatremia : nausea, anorexia, thirst, weight gain, oliguria, weakness, fatigue, and muscle cramps.Usually become apparent when serum sodium falls to the115–120 mEq/l range.

DIAGNOSTIC TESTS SIADHo Diagnosis based on findings:o Hyponatremiao Decreased serum osmolarityo Euvolemia (hypotonic hyponatremia)o High urine specific gravityo Urine sodium more than 20 mEq/lo Urine osmolality greater than 1,400, normal or

decreased blood urea nitrogeno (BUN) and creatinine, hypouricemia, and

normal renal, adrenal, and thyroid function

Other potential causes of hyponatremia (e.g.,congestive heart failure, cirrhosis, adrenal insufficiency, Addison’s disease, and hypothyroidism) must be evaluated and ruled out during the diagnostic workup.

DIAGNOSTIC TESTSTest Normal

ResultAbnormalResult

Explanation

Urine osmolality

Blood osmolality

Serum sodium

Urine sodium

200–1200 mOsm/L

275–285 mOsm/L

136–145 mEq/L

20 mEq/L

>1200 mOsm/L

<275 mOsm/L

<120 mEq/L

>20 mEq/L

Excretion of inappropriately concentrated urine and hyponatremia caused by overproduction of ADH

Water loss in urine and hypernatremia lead to hemoconcentration; levels above 320 mOsm/L are considered “panic levels” and require immediate intervention

Sodium loss in the urine leads to hyponatremia and hemodilution

Sodium loss in the urine

Other Tests: Blood urea nitrogen, urine specific gravity, radioimmunoassay of ADH

SIADH

RISK FACTORS• Cancer – most common is small cell cancer of the lung• Meningitis, cerebral abscess, head injury, tumor• Pneumonia, TB, lung abscess• Porphyria, alcohol w/d• Drugs –opiates, chlorpropramide, carbamezapine, vincristine• Failure of vital organs: heart, lung, liver, and kidney• Surgery of nervous system

SIADH

HEALTH PROMOTION STRATEGIES Things you should do• Keep daily weight log• Limit the amount of fluids • Try drinking orange juice, tomato juice, or beef and chicken broth.• Do not stop your medication without first talking to your doctor • Stop smoking

Call your doctor • If the symptoms get worse, especially weight gain, low urine output, increased thirst, or personality changes• Uncontrolled pain

SIADH

RESOURCES

• Find-an-Endocrinologist:• www.hormone.org or call• 1-800-HORMONE (1-800-467-6663)

•The Hormone Foundation:• Pituitary Information:• www.hormone.org/pituitary/index.cfm

•Medline Plus: www.medlineplus.gov

•Pituitary Society: www.pituitarysociety.org

SIADH

REFERENCES

•Beddoe, A. (2011). Syndrome of Inappropriate Antidiuretic Hormone Secretion (SIADH). CINAHL Nursing Guide, Retrieved from EBSCOhost.

•Flounders, J. (2003). Syndrome of inappropriate antidiuretic hormone. Oncology Nursing Forum, 30(3), E63-7. Retrieved from EBSCOhost.•Langfeldt, L., & Cooley, M. (2003). Syndrome of inappropriate

antidiuretic hormones secretion in malignancy. Clinical Journal of Oncology Nursing, 7(4), 425-430.

doi:10.1188/03.CJON.425-430

REFERENCES

•Sole, M., Lamborn, M., & Hartshorn, J. (2001). Introduction to Critical Care Nursing (3rd ed.). Philadelphia, PA: W.B.

Saunders Company.•Sommers, M., Johnson, S., & Berry, T. (2007). Syndrome of Inappropriate Antidiuretic Hormone (SIADH). In , Diseases & Disorders: A Nursing Therapeutics Manual, 3rd ed Philadelphia, Pennsylvania: F.A. Davis Company. Retrieved from EBSCOhost.•Terpstra, T., & Terpstra, T. (2000). Syndrome of inappropriate antidiuretic hormone secretion: recognition and management. MEDSURG Nursing, 9(2), 61-70. Retrieved from EBSCOhost.•Van Der Lubbe, N., Thompson, C., Zietse, R., and Hoorn, E., The

clinical challenge of SIADH—three cases NDT Plus (2009) 2(suppl 3): iii20-iii24 doi:10.1093/ndtplus/sfp155

Any questions?