Disorder of Anterior Pituitary Disorders

Anterior Pituitary Gland Secretes:

- Growth Hormones (GH)
- Prolactin
- ACTH, TSH, FSH, LH

Disorders of Anterior Pituitary (Adenohypophysis)

Acromegaly
Hypofunction of Pituitary Gland
Pituitary Surgery

Acromegaly

Overproduction of growth hormone
- caused by a benign GH-secreting pituitary adenoma

Pathophysiology of Acromegaly

Results in overgrowth of soft tissues & bones in hands, feet + face

- develops after epiphyseal closure (bones in arms + legs DON'T cont. to grow)

Life Expectancy w/ Acromegaly

Reduced 5-10 years
- due to CVD, DM, + colorectal cancer

Diagnostic Tests for Acromegaly: IGF-1

- Insulin-like growth factor
- Mediates peripheral actions to GH
- GH rises = IGF-1 levels

Diagnostic Tests for Acromegaly: Oral Glucose Tolerance Test (OGTT)

GH con. normally falls during OGTT → glucose inhibits GH secretion

- in acromegaly → GH don't fall & sometimes rises (+ result)

Diagnostic Tests for Acromegaly: Pituitary Adenomas

MRI or CT scan w/ contrast can detect pituitary adenomas
- a complete eye exam is completed → tumor may cause pressure on optic nerves

Treatment for Acromegaly: Surgery

Not an immediate option ( try other methods first)
- Hypophysectomy
- Radiation

Hypophysectomy

Removal of pituratiry
Tx of choice
- esp. for smaller pituitary tumors
- GH levels are ↓ and IGF-1 levels ↓ within weeks

Treatment for Acromegaly: Radiation

Given to pts w/ large tumors or GH levels > 45 ng/mL

Drug Therapy for Acromegaly: Octreotide (Sandostatin)

Somatostatin Analog
- ↓ GH levels to normal in many pts
- given SQ 3x a week

Drug Therapy for Acromegaly: Long-acting Somatostatin Analogs

Available as IM injections q 4 weeks
- Octreotide (Sandostatin LAR)
- Pasireotide (Signifor)
- Ianreotide SR (Somatuline Depot)

Considerations with Somatostatins Analogs

GH levels are measured q 2 weeks then q 6 mths
- until desired response is achieved

Drug Therapy for Acromegaly: Dopamine Agonists - Bromocriptine

Reduces GH secretion from tumor
- may be given w/ somatostatin analogs if surgery doesn't work

Drug Therapy for Acromegaly: GH Antagonists

Blocks hepatic production of IGF-1
- drug: Pegvisomant [Somavent]

CMs of Acromegaly

1. Thickening & enlargement of the bony/soft tissues
2. Proximal muscle weakness, joint pain (can be severe)
3. Carpal tunnel syndrome
4. Skin changes (thick, leathery, oily)
5. Hypertrophy of vocal cords
6. Visual changes + headaches

GH & Insulin

Antagonizes its action → polydipsia & polyuria
- causes ↑ of blood sugar & hyperglycemic symptoms

Hypopituitarism

Decrease in 1 or more pituitary hormones
- deficiencies in GH and gonadotropin (LH, FSH) are common

Selective Hypopituitarism

Deficiency in 1 pituitary hormone

Panhypopituitarism

Total failure of pituitary glands → results in deficiency of all pituitary hormones

What can hormone deficiency lead to?

End-Organ Failure
- TSH → hypothyroidism
- ACTH → acute adrenal insufficiency and hypovolemic shock

Causes of Pituitary Hypofunction

• Pituitary tumor
• Autoimmune disorders
• Infections
• Infarction (sheehan syndrome)
• Destruction of pituitary gland
- from surgery, radiation or trauma

CMs of Hypopituitarism

Vary by type & degree of dysfunction
- Headaches
- Vision changes (decreased visual acuity, decreased peripheral vision)
- Loss of smell
- N/V
- Seizures

CMs of Hypopituitarism: Changes in Lab Results

↓ pituitary hormones
•↓GH
•↓ ACTH
•↓ TSH
↓ end-organ hormones
•↓ cortisol
•↓ T3 & T4

Tx for Hypopituitarism

1. Surgery & Radiation for tumors
2. Life-long hormone therapy
3. Somatropin for GH

Somatropin (Genotropin, Humatrope, Omnitrope) - GH Replacement

Recombinant human GH used for long-term hormone therapy
- given SQ daily in evenings
- doses variable based of symptoms, IGF-1 levels & side effects

Side Effects of GH Somatropin (Replacement)

- Fluid retention w/ swelling in feet + hands
- Muscle and joint pain
- Headache

W/ Somatropin Tx, Pt Reports:

- Increased energy
- Increased lean body mass
- A feeling of well-being
- Improved body image

Individualized Hormone Therapy for Tx of Gonadal Deficiency

Not life-threatening but improves sexual function & general well-being
- Estrogen
- Progesterone
- Testosterone

Process of Hypophysectomy

Usually done via endoscopic transsphenoidal approach
- removal of gland = permanent loss of all pituitary hormones (requires life-long replacement of all hormones)

When is radiation therapy used?

1. Surgery doesn't produce a cure
2. Pts aren't candidates for surgery
3. Size of tumor has to be reduced before surgery

Stereotactic Radiosurgery

Used on small, surgically inaccessible pituitary tumors
- gamma knife surgery
- proton beam
- linear accelerator

NSG Interventions Post-Pituitary Surgery: Vision Changes

Assess pt for hematoma that may compress optic nerves or optic chiasma
Monitor:
- Peripheral vision
- Visual acuity
- Extraocular movements
- Pupillary response

NSG Interventions Post-Pituitary Surgery: CSF Leaks

HCP msy put a balloon-tipped cath or gauze into sphenoid sinus
- HOB ↑ 30 deg. & bedrest
- dont blow nose for 48 hrs
- dont bed @ waist
- give high-fiber diet

Moustache Dressing for Drainage

Monitor regular
Check any clear dressing w/ dipstick for glucose & protein
- glucose level > 30 mg/dL = CSF leakages from brain = risk for meningitis

CSF Leaking Into Sinuses

Pt may report a persistent & severe generalized or supraorbital headache
- leaks usually resolve within 72 hrs w/ HOB ↑ & bedrest
- daily spinal taps to reduce pressure if leak persists

Complications within Pituitary Disorders: Diabetes Insipidus (DI)

- Urine output > 200 mL/hr x 3 hrs
- Specific gravity < 1.005
- Elevated serum sodium & thirst
- Tx w/ Desmopressin acetate (DDAVP)
- Tx for hypovolemia: fluid replacement

Complications within Pituitary Disorders: Syndrome of Inappropriate ADH (SIADH)

Occurs on 4th post-op day
- release of ADH → fluid retention → dilutional hyponatremia
- symptoms: Headache, Sodium levels < 125 mEq/L, Vomiting, ↓ LOC