Pituitary Disorders

What 2 hormones does the posterior pituitary produce?

ADH and oxytocin

When is ADH released and what does it do?

• ADH is released from the posterior pituitary gland in response to elevated serum sodium (osmolality). 

• It then travels to the distal tubules and collecting ducts of the kidney, causing them to be more permeable to water, resulting in its retention back into circulation. 

• Leads to decreased urine output and more concentrated urine 

• Retains water 

Syndrome of Inappropriate Antidiuretic Hormone (SIADH): 

Too much ADH is released despite low serum osmolality and hyponatremia

• Too much ADH is released from the posterior pituitary. 

• It travels to the kidney, causing too much water retention in the distal renal tubules and collecting ducts

• Causes:

  • Malignancy 

  • CNS disorders 

  • Medications 

Manifestations of SIADH

• Low urine output

• Increased body weight

• Decreased serum sodium (and osmolality)

• Increased urine concentration (osmolality/specific gravity)

• Increased thirst, dyspnea on exertion, fatigue 

If the patient with SIADH becomes severely hyponatremic, he/she could experience which manifestations?   

CASH

• Confusion, abdominal cramps, seizures, headache, lethargy, coma 

What lab values for sodium, serum osmolality, and urine specific gravity show SIADH?

• Serum sodium < 135mEq/L 

• Serum osmolality <280 mOsm/kg 

• Urine specific gravity >1.030 

 

Nursing Interventions for SIADH

• Fluid restriction

  • helps with the fluid overload and low sodium due to low osmolality 

• Seizure and fall precautions: p

  • patient is at risk of severe hyponatremia, which causes CNS issues such as seizures 

• Medications: 

  • Furosemide: loop diuretic will help decrease intravascular fluid  

  • Small amounts of hypertonic saline: will help bring severely low sodium up 

  • Vasopressor receptor antagonists (block ADH receptors) such as conivaptan: blocks ADH effect to decrease water resorption 

Teaching for SIADH

• Fluids – teach about symptoms of fluid volume overload and importance of fluid restriction  

• Daily weight – Teach how daily weights help monitor improvement of fluid volume overload 

• S/sx of fluid and electrolyte imbalance – teach about signs of hyponatremia such as confusion, abdominal cramps, seizures, headache, lethargy. Also signs of fluid overload such as edema, weight gain, dyspnea, high Bp, bounding pulse,etc 

Diabetes Insipidus

Deficient production or release of ADH or decreased renal response to ADH results in increased urine output and increased serum osmolality 

• *Central: problem with ADH production, transport, or release 

  • Ex of causes: tumor, head injury, infection, pituitary damage in surgery 

• Nephrogenic: problem with renal response to adequate ADH 

  • Ex of causes: medications, renal damage or disease 

• Primary: excess water intake 

  • Ex of causes: lesion in thirst center, psychiatric disorder 

Clinical Manifestations of Diabetes Insipidus

• Decreased urine concentration (osmolality/specific gravity)

• Increased serum sodium (and osmolality)

• Increased urine output

• Dehydration 

• Polydipsia and polyuria (increased thirst and increased urination) 

If the patient with DI becomes severely hypovolemic, list two manifestations may he/she experience?   

Poor skin turgor, dry mucous membranes, hypotension, tachycardia, hypovolemic shock 

If the patient with DI becomes severely hypernatremia, list two manifestations may he/she experience?   

SALT

Skin flushed, agitation/irritability, lethargy, thirst

• severe - seizures, coma

What will lab values/tests will you look at when diagnosing someone with diabetes insipidus?

• Urine output >200 mL/hr 

• Urine specific gravity <1.005 

• Water deprivation test 

• ADH levels 

• Serum sodium >145 mEq/L 

• Serum osmolality >295 mOsm/kg 

Nursing Interventions for DI

• Fluid replacement: helps dilute blood to bring sodium and osmolality levels back down to normal.  

• Hormone replacement (desmopressin acetate [DDAVP]): helps kidneys retain water