Week 2: Introduction to Endocrine Disorders and Disorders of the Posterior Pituitary Gland (SIADH and DI)

Antidiuretic hormone (ADH)/Vasopressin

-potent vasoconstrictor (RAISES BP)

-regulates fluid volume

When is ADH released?

-high serum osmolality

-when BP is LOW

-when blood volume is LOW

-releases when water needs to be absorbed

Relationship with Serum osmolality

ELEVATED = Diabetes Insipidus

DECREASED = SIADH

Relationship with Urine osmolality

ELEVATED = SIADH

DECREASED = Diabetes Insipidus

Diabetes Insipidus and ADH

UNDERPRODUCTION of ADH hormone

Syndrome of inappropriate antidiuretic hormone (SIADH) and ADH

OVERPRODUCTION of ADH hormone

S/s of Diabetes ADH

-polyuria

-polydipsia (thirst)

-fluid loss

-serum hyperosmolality

-hypernatremia

-dilated urine (light urine)

S/s of SIADH

-fluid retention

-hypoosmolality

-hyponatremia

-concentrated urine (dark urine)

Relationship between ADH and water absorption

LOW ADH = LESS water absorbed

HIGH ADH = HIGH water absorbed

Types of Diabetes Insipidus (DI)

-NOT enough ADH

-neurogenic: underproduction of ADH from hypothalamus or pituitary

-nephrogenic: renal tubules dont respond to ADH

S/s of hypernatremia:

-hypovolemia and dehydration

-muscle weakness

-mental status changes

-hallucinations (especially elderly)

How to treat hypernatremia?

HYPOTONIC IV FLUIDS

-restore fluid balance

S/s of excessive urine output?

-thirst

-dehydration

-hypovolemic shock

--tachycardia, hypertension

How to treat excessive urine output?

MAINTAIN ADEQUATE HYDRATION

Nursing considerations for Diabetes Insipidus:

-monitor I&O

-administer hydration (HYPOTONIC IV fluid)

-monitor for hypovolemic shock (tachycardia, hypertension)

-monitor electrolytes and osmolality

-monitor LOC (think Na)

Vasopressin/Desmopressin (DDAVP)

synthetic replacement of Vasopressin

-reduces urine production

-increases BP in patients w/shock

can only be used in central or neurogenic DI

Nursing considerations for DDAVP:

-monitor for water intoxication (i.e too much absorption)

-monitor for seizures or change in LOC

-can increase BP in patients w/shock

-monitor for HTN, tachycardia, chest pain

Specific gravity range:

1.005-1.030

-higher means urine is very concentrated = less water more solutes

Serum osmolality range:

275-295

dehydration = high osmolality

overhydration = low osmolality

Function of hypothalamus vs pituitary gland:

hypothalamus: releases hormones that target pituitary

pituitary: releases actual hormone itself with direction of hypothalamus

3 Hormones released by thyroid:

-Thyroxine (t4) most of this hormone

-Triiodothyronine (t3)

-Calcitonin

T3 and T4 functions:

-stimulate energy use

-stimulate the heart

-promote growth and development

think getting everything moving!

Calcitonin function:

decreases Ca plasma levels

-inhibits resorption of Ca from bone

-increases calcium excretion by kidneys

think tone it down (the calcium)

PTH function:

-high Ca=low PTH

-low Ca=high PTH

-regulates serum calcium levels

-stimulates renal conversion of vitamin D

Causes of SIADH:

-shock, trauma, stress, pain, nausea, surgery

-chronic like cancer or genetic disorders

S/s of hyponatremia

-SEIZURES

-loss of energy, mental status changes

-muscle weakness

-headache (cerebral edema)

Sodium reference range

135-145

Nursing considerations for hyponatrema:

-treat underlying cause

-replace lost sodium

-water restriction (typically for dilutional hyponatremia)

-seizure precautions

Nursing considerations for SIADH:

-daily weights, monitor I&O, assess lung sounds

-fluid restriction of 800-1000mL/day

-HOB elevated no more than 10 degrees

-administer hypertonic saline infusion (3% NaCl)

-offer distractions for fluid restriction

-monitor serum sodium and osmolality

-monitor urine specific gravity

ANP function

opposite of ADH

-results in higher fluid and sodium excretion

Why does keeping the HOB below 10* important?

-higher chance of stimulating ANP release

-aids in fluid and sodium release

-helpful for patients with SIADH and their excess fluid

Potassium reference range

3.5-5.0

Adverse effects of DDAVP:

-water retention

-hyponatremia

-cerebral edema

-headache is most common

When a patient has Diabetes Insipitus, what kind of fluids should they be getting? Avoiding?

-replace with 5% Dextrose in water (D5W)

-avoid hypertonic and excess sodium

Two types of hyponatremia:

-dilutional hyponatremia

-depletional hyponatremia

Euvolemic hyponatremia

-no edema

-occurs during SIADH

-total body water is increased

-total body sodium is normal

Cancer and ADH relationship:

cancer cells can produce and release ADH

Severe hyponatremia range

less than 125

Moderate hyponatremia range

125-130

Mild hyponatremia

130-135