2
Disorders of the Posterior Pituitary
Diabetes Insipidus
Syndrome of Inappropriate Antidiuretic
Hormone (SAIDH)
Posterior Pituitary
• Posterior pituitary hormones are
actually
produced in the
hyopthalamus and
only stored in the posterior
pituitary
• Posterior pituitary hormones
– Antidiuretic hormone
(ADH)
– Oxytocin
• The hormones secreted by the
posterior pituitary are
– Antidiuretic hormone
(ADH) (Also call
vasopressin)
– and oxytocin.
• ADH contributes to fluid
balance by
– Controlling renal
reabsorption of free water
– It also has potent
vasoconstrictive
properties.
Posterior Pituitary
• Antidiuretic
hormone (ADH)
(Also called
vasopressin)
– Excess: Syndrome of
• Disorders/diseases
resulting from
dysfunction
– Deficiency: Diabetes
Inappropriate ADH
secretion (SIADH)
Insipidus
SIADH
Posterior Pituitary Hypersecretion
SIADH - Syndrome of Inappropriate
Hormone Secretion
• ADH (anti-diuretic hormone) is a hormone made in the pituitary
gland.
• ADH does what the name says it stops urination - diuresis
• Slowing or stopping urine production leads to fluid retention.
• That in turn causes a dilution of body sodium
SIADH - Syndrome of Inappropriate
Hormone Secretion
• Depending on the rapidity & the extent of the sodium drop, a
battery of S/S appear.
• Lethargy, weakness, & foggy thinking are common. Personality
changes can happen.
• Low sodium levels often make pt nauseated
• If the situation is not corrected, seizures, coma, & even death
can follow.
Syndrome of Inappropriate Antidiuretic
Hormone Secretion - SIADH
• Results from many
• SIADH occurs
when there is
too much vasopression (ADH)
with
inappropriate water retention
and
decreased blood Na levels
different conditions and drugs
• May be produced by
certain tumors such as
lung cancer
or may result from
chronic lung diseases.
Medicines associated with
SIADH include common
meds as antidepressants,
antianxiety agents,
antipsychotic agents, seizure
meds, and desmopressin
(DDAVP)
Syndrome of Inappropriate Antidiuretic
Hormone Secretion - SIADH
• Results from
–
–
–
–
Inability to produce & secrete dilute urine
Water retention
Increased extra cellular fluid volume
Hyponatremia Diseases that affect the hypothalamus
Dx of SIADH
• The following criteria should be fulfilled before a
diagnosis of SIADH can be made:
• persistent excretion of concentrated urine with no reason
for ADH release
• normal renal and adrenal function
• no edema or hypovolaemia should be present
• the urine osmolarity should be greater than the serum
osmolarity
Physical Assessment of SIADH
• Initially, S/S are R/T retention of water.
• Most common complaints
– GI disturbances-loss of appetite, N,V
• Nurse
– Weighs pt & documents any recent weight gain
– Checks pt extremities for presence of edema
• Pt with SIADH have free water, not salt, that is retained &
edema is not usually present due to intracellular free water
Assessment-Clinical Manifestations of SIADH
• Water retention, hyponatremia, & resulting fluid shifts have an
effect on CNS function, especially when serum sodium level drops.
Normal serum Na 135-145.
S/S occur when serum Na level drops below 125,
and especially below 115
• Clinical S/S
• Lethargy, headaches, hostility, uncooperativeness, disorientation
• Early sign -Change in LOC
• Neurological S/S can progress from lethargy and headaches to
decreased responsiveness, seizures, and coma.
• Nurse assess deep tendon reflexes, which are often < or sluggish
• V/S changes-tachycardia associated with increased fluid volume &
hypothermia associated with CNS disturbance
Normal Lab Values
serum osmolality
(285-295 mOsm/kg)
sodium
(Na 135-145 mEq/L)
Urine osmolality -24 hr specimen
500-800 mOsm/kg H20
chloride (95-105 mEq/L)
-Random specimen:
50-1200 mOsm/kg/H20
Osmolality is measures in
milliosmoles per kilogram
of water (mOsm/kg).
The major determinants of
plasma osmolality are Na,
glucose, & urea
Urine specific gravity
1.003-1.030
1.002-1.035
High=dehydration
Low=diabetes insipidus
concerntrated urine
> than 50-100 mOsm/kg
with
normal vascular volume
and
normal renal function
Lab Assessment in SIADH
• Extracellular fluid volume expansion affects electrolyte levels in the
serum and the urine
• Elevated urine sodium levels and specific gravity reflect an
increased concentration of the urine
• Serum sodium levels are decreased, often as low as 110 mEq/L
(normal serum sodium 135-145 mEq/L) due to extracellular volume
expansion and increased Na excretion
• Fluid retention causes changes in both plasma and urine osmolality
• Plasma osmolality is decreased, and the urine is hyperosmolar in
relation to the plasma
Osmolality
Urine osmolality -24 hr specimen 500-800 mOsm/kg H20
Random specimen: 50-1200 mOsm/kg/H20
• Osmolality is measures in milliosmoles per kilogram of water
(mOsm/kg). The major determinants of plasma osmolality are Na,
glucose, & urea.
• The Kidneys are mainly responsible for maintaining the concentration
of body fluids within this range of osmolality.
• When the plasma osmolality becomes abnormal,
changes in the level of antidiuretic hormones (ADH)
cause the kidneys to
conserve or increase the excretion of water
to return the osmolality to normal
Posterior Pituitary hypersecretion - SIADH
Symptoms - fluid retention
low serum osmolality
(normal285-295 mOsm/kg)
dilutional low sodium
(normal Na 135-145 mEq/L)
low chloride
(normal95-105 mEq/L)
Causes Diseases effect the hypothalmus
pneumonia
TB
positive pressure ventilation
Trauma
concerntrated urine
(> than 50-100 mOsm/kg)
with normal vascular volume and
normal renal function
muscle cramps & weakness
cerebral edema, lethargy, anorexia,
headache, seizures, coma.
AIDs
delirium tremens
Ectopic ADH secreting
tumor
SIADH - Diagnostic Tests
• Blood & Urine tests
• Must have
– low serum sodium
– low plasma osmolality
level
– Inappropriated
concentrated urine
(increased urine osmolality
level)
• These tests indicate
– excess of body water
relative to the amount of
body sodium.
• In other words, ADH is
inappropriately holding onto
too much water.
• Important to eliminate other
causes of a low sodium level,
such as hypothyroidism or
adrenal insufficiency, before
settling on a dx of SIADH
• Rx- removing the offending
drug or tumor, & treat the
Posterior Pituitary: SIADH,DI
• *Affect kidney’s ability to concentrate urine*
• Measured by urine specific gravity
– Measures number and size of particles
– Normal: 1.003 - 1.030
– High = dehydration
– Low = Diabetic Insipidus 1.001-1.005
– Concentrated urine: SIADH
– Dilute urine: DI
Posterior pituitary: SIADH
• ADH excess = water intoxication
• water is reabsorbed, so assess for
– increased blood volume, fluid retention
– concentrated urine, low urine output
– dilutional hyponatremia (same Na, more H20)
• muscle cramps and weakness
• anorexia, n/v, irritable, confused, disorient, seizure
SIADH and Hyponatremia
• Hyponatremia- a lower than normal concentration of sodium in
the blood
• Caused by inadequate excretion of water of by excessive water
in the circulating bloodstream
• In a severe case the pt may experience water intoxication,
with confusion and lethargy, leading to muscle excitability,
convulsions, and coma.
• Treatment: Fluid and electrolyte balance may be restored by IV
infusion of a balanced solution or a fluid restricted diet.
SIADH
Diagnosis & Treatment
Diagnosis
measure urine volume
and
osmolality
Na < 134mmol/L
se osmol >280mmol/kg
SG>1005
low BUN, creatinine, Hb, Hct.
Treatment
If Na<125
Restrict fluids 800 - 1000
ml/day.
Daily weigh
Monitor
3% - 5% Saline solution IV
Lasix if Na<105
(cardiac symptoms)
SIADH
• Diagnostic Study
– Hyponatremia
– Decreased plasma
osmolality
– Urine sodium and urine
osmolality elevated
– Elevated ADH
levels++++++
– Normal renal, adrenal, &
thyroid functions
• Nursing Assessment
• Headache,Personality change,
Confusion,Irrritability,
Dysarthria(difficult, poorly
articulated speech),
Lethargy,Impaired memory
• Restless, weakness, fatigue,
gait disturbances
• Weight gain+++++
SIADH Treatment
• Water Restriction is the cornerstone of treatment
• Decreased water intake allows serum sodium level to rise normally.
• The maximum amount of water that pt with SIADH are allowed to
drink is just slightly more that the amount of urine they produce
• Pt must have regular serum sodium measurements to ensure that the
water restriction has been effective
• Dehydration- The most concerning potential side effect from
treatment is dehydration.
SIADH treatment
•
•
•
•
Restrict fluid intake (800-1000 cc/day)
Daily weight
Strict I & O
Monitor urine specific gravity
0.9 NS infusion(to raise the serum Na level if water
intoxication is severe)
• Monitor for hyponatremia
• Lasix may be admin to block circulatory overload
• Drugs-demeclocyclin HCL & lithium-may be admin to
block renal response to ADH, intereferes with action of ADH
• Drugs - Phenytoin - inhibits ADH release
• Surgery & Chemo -to remove or destroy neoplasms that may
be the underlying cause of this syndrome
SIADH treatment
• Demeclocycline (Declomycin)
• Lithium
• Used for:
– Excess secretion of ADH or SIADH
• Action:
– Inhibits ADH action in kidney
– Blocks renal response to ADH, interferes with action of ADH
• Therapeutic outcome:
– Decreased urine specific gravity
Analysis - Nursing Diagnosis - SIADH
• 1. Fluid Volume Excess R/T compromised regulatory
mechanism, excess ADH
• 2. High Risk for Injury R/T an altered level of
consciousness, confusion, & the possibility of seizures
• 3. Altered Nutrition: Less than Body Requirements R/T an
inability to ingest or digest food or absorb nutrients
because of biologic factors (ex-anorexia, N/V)
• 4. Altered Thought Processes R/T physiologic changes
within the central nervous system
Planning & Implementation
• Planning: Pt Goals
• The primary goal is that the pt’s
fluid balance will be restored
• Interventions to treat SIADH
(Pt Care Plan) consists of
• Restriction water intake
• Using diuretics to promote the
excretion of water
• Administering drugs that
interfere with the action of ADH
• Replacing lost sodium
• Fluid Restriction
• Any excessive free water intake
will further dilute the serum
sodium concentration
• Strict I&O, daily weights,
guides the determination of the
degree of fluid restriction
necessary. A wt gain of 2
pounds (or 1 Kg) or more per
day or a gradual increase during
several days is cause for
concern.
• A 1 Kg weight increase is
equivalent to 1000ml fluid
retention (1Kg = 1 L)
Planning &
Implementation
• Hypertonic saline (3% NaCl) may be
used to treat SIADH
– Helps correct serum sodium level
– Raises Na osmolality in the blood
– Removes excess intracellular fluid
– Cells shrink in hypertonic solution
• Drug Therapy
• Diuretics are sometimes
used to treat pt with
SIADH, to rid the body
of excessive fluid,
especially if CHF
• IV saline is given cautiously because it
results from fluid overload may contribute to the fluid overload
already present & precipitate an episode
of CHF.
• If diuretics are used, be
aware of potential effect
of electrolyte losses;
• If the pt needs routine IV fluids, the MD
sodium loss can be
orders a solution in saline (5% dextrose
potentiated, which further
in saline) rather than a solution in water.
contributes to the clinical
picture of SIADH
Planning & Implementation
•
•
•
•
High Risk for Injury
Promote safety
Monitor pt neuro status
Subtle Changes, such as muscle
twitching before neuro S/S
progress to seizures or coma.
Check LOC to time, place, &
person because disorientation
may be present.
• Confusion is another neuro
sign. Nurse reduces
environmental stimuli & explain
interventions in simple terms.
• Flow sheets contain ongoing
info about LOC, motor &
sensory neuro assessment, &
pertinent lab data helpful in
detecting trends.
• Decreased LOC and seizures
are complications of the low
serum sodium level R/T SIADH
Nursing issues
• Monitoring fluid balance(s/s fluid retention):
• Cardiac problems
(water reabsorbed so >bld volume):
• Neurological problems
coma,):
• Energy limitations
(headache seizures,cerebral edema,
(muscle cramps, weakness):
• Allied health problems
(anorexia):
• Risk for injury: (confusion, muscle tremors, etc.)
Nursing issues
• Fluid Volume Excess R/T inability to excrete water
• Hyponatremia with plasma hypo-osmolality
• Weight gain
• Potential for Injury
– Institute seizure precautions and safety measures
– Reorient confused pt
• Prevent complications of immobility
• Recognize decreased gastric motility due to hyponatremia,
combined with fluid restriction and decreased mobility - >constipation
Diabetes Insipidus
Posterior Pituitary
Diabetes Insipidus
• Uncommon syndrome
of posterior pituitary hypofunction
• S/S
– Increased thirst - polydipsia
– Increased urination - polyruia
• Results from
– ADH (Vasopression) deficiency, which prevents the kidneys
from reabsorbing water
– Inability to conserve water
Posterior pituitary : DI
• Diabetes insipidus: “to pass through”
• Decreased ADH = diuresis
• Water is lost, so assess for:
– Kidneys produce large amts of dilute urine
(5L-10L in 24hrs)
– low urine specific gravity (1.001-1.005)
– polyuria (>urine output), polydipsia (>thirst)
– fluid deficit
• weight loss, turgor,dehydration, hypotension, constipation,
shock
Posterior Pituitary hyposecretion
Diabetes Insipidus
• Symptoms-
• Thrist & polyuria 5 - 20L/day
•
•
SG < 1005
Urine osmol < 100 mmol/L
•
Se osmol > 295 mmol/kg
• Urine specific gravity low
(1.001-1.005)
• Urine osmolality decreased
(50-200 mOsm.kg)
•
Nocturia
• Urine less concentrated than
plasma
•
Weakness => weight loss,
hypotension, tachycardia,
constipation, shock.
• Plasma osmolality elevated
(>295 mOsm/kg)
• Sleep deprivation-due to interrupted
by need to drink fluids & urinate
• Hypernatremia in blood
Diabetes Insipidus
Etilogy
• Familial or idiopathic
• Head injury
• Neuorsurgery
• Damage to the
hypothalamic areas that
produce ADH
• Cause
• Lesion of hypothalmus
interferes with ADH
synthesis/transport/relea
se
• brain tumour
• pituitary/cranial surgery
• head trauma
• CNS infection
• vascular disease.
Diabetes Insipidus
Etilogy
• Drug Related
• Ethanol &
Phenytoin (Classification: Antiarrhythmic, Anticonvulsant):
– Inhibit ADH secretion
• Lithium (Classification: Antimanic) &
Demeclocycline(Classification:anti-infective-Tetracycline):
– Inhibit ADH action in kidney
4 Types of Diabetes Insipidus
• 1) Neurogenic -also known as
–
–
–
–
–
central
hypothalamic
pituitary
neurohypophyseal
Caused by a deficiency of the
Antidiuretic hormone,
vasopressin
• 2) Nephrogenic-also known as
– Vasopressin - resistant
– Caused by insensitivity of the
kidneys to the effect of the
antidiuretic hormone,
vasopressin
• 3) Gestagenic-also known
as
– Gestestional
– Caused by a deficiency of
the antidiuretic hormone,
vasopressin, that occurs
only during pregnancy
• 4) Dipsogenic, a form of
primary polydipsis
– Caused by
• Abnormal thirst and the
• Excessive intake of water
or other liquids
• Diagnosis D.I.
Diagnosis & Rx
• History and examination
Diabetes Insipidus
•
Water deprivation test
(see next slide)
• Vasopressin challenge test
(see next slide)
• 24 hours urine
• High sodium in blood
• MRI of pituitary, hypothalmus
and skull to see damaged areas
• Treatment
• Intravenous fluids
Hypertonic saline IVExtracellular solution to pull
fluid from outside the cell to
inside the cell
•
Vasopressin SC/IM/IV, nasal
prep
•
Long term DDAVP
(Desmopression) nasal prep.
(analog ADH)
Diagnosis - Fluid Deprivation Test
(To identify cause of polyuria)
• Baseline VS, then check hourly-allows RN to detect changes,
esp postural hypotensin & tachycardia
• Deprive pt of fluid-Observe for compliance with fluid restriction
• Hourly- urinary output, specific gravity, & osmololity
• Urine test results determine whether testing can proceed.
– Testing can proceed if urinary osmolality stabilized for 3 samples
and 3% wt loss is noted
Dx- Vasopressin challenge
• Order for 5 Units of aqueous vasopressin sc
• Continue hourly urinary measurements
• Vasopressin triggers and ongoing assessment detects
Changes in urinary specific gravity and osmolality
– Specific gravity & osmolality decrease with primary
and secondary diabetes insipidus
– No response is seen with nephrogenic diabetes
insipidue
Diabetes insipidus treatment
• Vasopressin (Pitressin) : is ADH
• Classification: Hormone (antidiuretic)
• Uses: Treatment of central diabetes insipidus sue to deficient
antidiuretic hormone.
• Route/Dose: IM, sc, nasal spray
• Nsg Implications:
• replace fluid: saline and glucose
• monitor I & O
• check specific gravity
• observe electrolytes
• Monitor adverse reactions-abdominal cramps, angina, MI
Diabetes insipidus treatment
• Desmopressin (DDAVP)
• Classification: Hormone (andiuretic)
• Indication: Management of primary nocturnal eneuresis unresponsive
to other treatment modalities
• po, sc, IV, Intranasal
• Action: An anologue of naturally occuring vasopressin (antiuretic
hormone). Primary action is enhanced reabsorption of water in the
kidneys
• Therapeutic Effects: Prevention of nocturnal enuresis. Maintenace
of appropriate body water content in diabetes insipidus.
• Nsg Implication: Monitor urine & plasma osmolality & urine volume
frequently. Assess pt for symptoms of dehydration (excessive thirst,
dry skin & mucous membranes, tachycardia, poor skin turgor)
Weigh pt daily & assess for edema
Observe for Water Intoxication
with all agents
• ADH excess = water intoxication
• water is reabsorbed, so assess for
– increased blood volume, fluid retention
– concentrated urine, low urine output
– dilutional hyponatremia (same Na, more H20)
• muscle cramps and weakness
• anorexia, n/v, irritable, confused, disorient, seizure
Diabetes Insipidus
• Fluid Volume Deficit R/T inability to conserve water
– Thirst, dry mucous membranes
– Decreased skin turgor
– Hypotension, tachycardia
– Hemoconcentration, plasma hyperosmolality, hypernatremia
– Increased urine output
– Dilute urine-monitor specific gravity
Nursing Issues
• Fluid and electrolyte imbalance:
•
•
•
•
•
•
•
•
R/T >diuresis,
monitor urine and plasma osmolarity
monitor specific gravity (usually will be low with >diuresis)
monitor urine volume (usually will be high 5-10L in 24 hr)
Therapy successful when urine output and specific gravity begin to
return to normal
monitor s/s dehydration
weight pt daily & assess for edema
Fluid volume deficit
Nurse will monitor for hypotension, constipation, shock
• Sleeping problems: R/T nocturia & increased thirst
•
• Education: