SIADH

Syndrome of Inappropriate Antidiuretic Hormone Secretion (SIADH) Is a condition where the kidneys secret too much ADH causing excess water retention.

Etiology and Pathophisiology ADH is released by the posterior pituitary and signals the kidneys to secret less H2O in the urine. Retained water in SIADH is usually caused by malignant tumors with the most common cancer linked to SIADH being small cell carcinoma of the lung. Other cancers in the thymus, colon, prostate, pancreas and lymph nodes are also linked to SIADH. Other causes of SIADH are medications, brain tumors, head trauma or Addison's disease.

Signs and Symptoms

Excess thirstLow urinary outputIncreased extracellular fluid volume without edema.Weight gain without edemaUrine specific gravity &gt;1.005Below normal sodium levels &lt;135 causing muscle cramping, pain, weakness stupor, seizurescomadeath. Severity of symptoms increase as Na+ levels fallWater intoxication (irritable, headache, stupor, personality changes, seizurescomadeath.)</li>Cerebral edema</li>Anorexia</li></ul> Diagnosis is made by Na+ levels &lt;134, urine specific gravity &gt; 1.005 and serum osmolality &lt;280. Serum osmolality much lower than urine osmolality is considered positive for SIADH.

<h2 data-rte-empty-lines-before="1">Nursing Considerations

Assessments

<ul data-rte-dragged="true">Water intoxication (headache, stupor, irritability, seizurecomadeath)</li>Hyponatremia - Pain, nausea, weakness, muscle cramping progressing to abdominal cramps, muscle spasms, vomiting, seizurecomadeath. Severity of symptoms is dependant on severity of hyponatremia.</li>Electrolyte imbalances</li>Fluid overload - Sudden weight gain without edema</li>Vital signs including daily weight</li>I&amp;O</li>Urine specific gravity</li>Level of consciousness</li>Heart and lung sounds</li></ul> Interventions

<ul>Fluid restriction of 500 - 1000 a day per physician's order depending on severity.</li>Patient should lay as flat as possible.</li>Provide ice chips and gum to help with thirst.</li>If symptoms are mild, Na+&gt;125, only treatmet may be fluid restriction.</li>If cause is medication related discuss med and dosage changes with primary.</li><li data-rte-new-node="true">Emotional support in helping patient and family deal with diagnosis, treatment and personality changes.</li></ul> Medications

<ul><li data-rte-new-node="true">3% - 5% hypertonic saline solution if Na+&lt;120. If used infusion should be done slowly to prevent rapid changes in sodium levels</li><li data-rte-new-node="true">Furosemide (Lasix) is a diuretic and increases excretion of H2O. It may be used if Na+&gt;125. Since Lasix increases calcium, sodium, potassium and magnesium losses supplementation of these may be needed.</li><li data-rte-new-node="true">Declomycin blocks the effect of ADH in the renal tubule causing more H2O secretion in the urine and less retention in the ECF</li><li data-rte-new-node="true">Vaprisol and Samsca are both ADH receptor antagonist and block receptor from binding with ADH thereby reducing the effects of ADH. They are used when volume is normal but Na+ is low. Patient should be watched closely for signs of rapid correction of sodium. Only used in hospitals.</li></ul> Patient Education

<ul><li data-rte-new-node="true">If supplemental electrolytes are used teach to take with meals and not concentrated.</li><li data-rte-new-node="true">How to manage thirst if on fluid restriction (ice chips, gum, mints, distraction.)</li><li data-rte-new-node="true">Signs and symptoms of water intoxication and hyponatremia (see above). Other electrolytes as well if Lasix is used.</li></ul>