Page 334 - Critical Care Nursing Demystified

Chapter 7 CARE OF THE PATIENT WITH ENDOCRINE DISORDERS 319

Syndrome of Inappropriate Antidiuretic Hormone (SIADH)

What Went Wrong?
An overproduction or excess of ADH occurs due to a continuous release of ADH
into the bloodstream, resulting in a condition known as syndrome of inappropriate
antidiuretic hormone or SIADH. SIADH occurs most often in older adults and
can be caused by a malignancy such as small cell lung cancer that releases ADH.
It can also be caused by the use of antidepressant and psychotropic medications.

Hallmark Signs and Symptoms
This condition is characterized by fluid retention, increased body weight, and
hyponatremia. Kidney tubules are stimulated to retain fluid through the excessive
release of ADH, resulting in severe overhydration and an increase in body fluid
volume. Sodium levels decrease (less than 120 mEq/mL) caused by an increase in
urinary sodium excretion, and dilutional hyponatremia occurs. In an effort to equal-
ize osmotic pressure, a fluid shift takes place from the extracellular to the intracel-
lular spaces. It is important to mention that aldosterone is normally released by the
adrenal glands to retain sodium but is suppressed by the condition of SIADH. The
lack of ADH and aldosterone suppression causes water to be retained, urine output Downloaded by [ Faculty of Nursing, Chiangmai University 5.62.158.117] at [07/18/16]. Copyright © McGraw-Hill Global Education Holdings, LLC. Not to be redistributed or modified in any way without permission.
to decrease, and excessive amounts of sodium to be lost in the urine. Although
there is a weight gain because of an expanded fluid volume, edema is absent due
to the loss and lack of sufficient sodium. Hyponatremia causes muscle cramps and
weakness. In addition to low concentrated urinary output and weight gain, danger-
ously low sodium levels can produce seizures, abdominal cramps, vomiting, muscle
twitching, cerebral edema, lethargy, anorexia, confusion, headaches, and coma.

3 Patient Assessment
The nurse should assess for a low, concentrated urinary output of less
than 30 mL/hr with a high specific gravity greater than 1.030 (normal value
1.005–1.030), increased body weight indicating fluid retention, and a decrease
in sodium levels. Identify any of the above-mentioned symptoms accompanying
dangerously low sodium levels. It is also important to obtain a baseline patient
weight and compare with daily weights, determine fluid intake and output and
vital signs, assess skin turgor for dehydration or edema, and obtain a list of cur-
rent patient medications. Goals of care include reduction of fluid intake and
sodium replacement therapy. Accurate measurement of intake and output is
required. Fluid intake is restricted to equal urine output until sodium levels
return to normal. Determine the patient’s status of elimination as constipation
can occur when fluids are restricted. To correct hemodilution caused by severe