ENDOCRINOLOGY

Parathyroid Gland

PARATHYROID Anatomy

PARATHYROID HORMONE Parathyroid hormone is the most

important endocine regulator of calcium and phosphorous concentration in the extracellular fluid.

This hormone is secreted from cells of the parathyroid glands and finds its major target cells in bone and kidney.

PHYSIOLOGIC EFFECT OF PARATHYROID HORMONE The effect of Parathyroid hormone goes

with the principle of negative feedback system, if calcium ion concentrations in extracellular fluid fall below normal, bring them back within the normal range.

In conjunction with increasing calcium concentration, the concentration of phosphate ion in blood is reduced.

PHYSIOLOGIC EFFECT OF PARATHYROID HORMONE Mobilization of calcium from bone:

Although the mechanisms remain obscure, a well-documented effect of parathyroid hormone is to stimulate osteoclasts to reabsorb bone mineral, liberating calcium into blood.

PHYSIOLOGIC EFFECT OF PARATHYROID HORMONE Enhancing absorption of calcium

from the small intestine: Parathyroid hormone stimulates this

process, by stimulating production of the active form of vitamin D in the kidney. Vitamin D induces synthesis of a calcium-binding protein in intestinal epithelial cells that facilitates efficient absorption of calcium into blood.

PHYSIOLOGIC EFFECT OF PARATHYROID HORMONE Suppression of calcium loss in

urine: Parathyroid hormone puts a brake on

excretion of calcium in urine, thus conserving calcium in blood. This effect is mediated by stimulating tubular reabsorption of calcium.

Another effect of parathyroid hormone on the kidney is to stimulate loss of phosphate ions in urine.

PHYSIOLOGIC EFFECT OF PARATHYROID HORMONE

HYPERPARATHYROIDISM Hyperparathyroidism results from

excessive secretion of parathyroid hormone (PTH). PTH promotes bone resorption, and hypersecretion leads to hypercalcemia and hypophosphatemia.

In primary hyperparathyroidism: one or more parathyroid glands enlarge and increase PTH secretion, most commonly caused by a single adenoma, but this may be a component of multiple endocrine neoplasia (all four glands usually involved).

HYPERPARATHYROIDISM In secondary hyperparathyroidism, a

hypocalcemia-producing abnormality outside the parathyroids causes excessive compensatory production of PTH. Causes include: rickets, vitamin D deficiency, chronic renal failure, and osteomalacia due to phenytoin (Dilantin).

PATHOPHYSIOLOGY

Tumor/hyperplasia

Hypercalcemia

Increase efflux

calcium

Demineralization of bonesOsteopenia/ osteomalacia/osteoporosis

Increase GIT Ca

absorptionNausea, vomiting, peptic ulcer,

pancreatitis

Increase Ca in kidney

Kidney stones, renal

problems

SIGNS AND SYMPTOMSNervous system

- Apathy- Psychological changes from irritability, neurosis to psychosis

Cardiovascular system- forceful cardiac contraction- cardiac dysrhythmias - hypertension

SIGNS AND SYMPTOMSRenal System- Polyuria- nephrocalcinosis- Kidney stones/renal calculi 55% of patients with primary hyperparathyroidism

Skeletal System- skeletal pain and tenderness- pain on weight bearing- shortening of body stature

SIGNS AND SYMPTOMS Musclular System

- fatigue- decrease muscle tone- muscle weakness

GIT- peptic ulcer- pancreatitis- abdominal pain ranging to the back- nausea and vomiting

DIAGNOSTIC FINDINGS Radioimmunoassay (confirms the diagnosis) X-rays showing diffused demineralization of

bones Spectrophotometry Ultrasound, MRI, thallium scan, and fine-needle biopsy have been used to

evaluate the function of the parathyroids and to localize parathyroid cysts, adenomas, or hyperplasia.

TREATMENT Surgery - The recommended treatment of primary

hyperparathyroidism is the surgical removal of abnormal parathyroid tissue.

The nursing management of the patient undergoing parathyroidectomy is essentially the same as that of a patient undergoing thyroidectomy.

NURSING MANAGEMENT Increased fluid intake (3-4L/day).

- to reduce risk of stone formation in the kidneys and relieve thirst due to polyuria.

Acid-ash fruit juices (prune juice, cranberry juice) ascorbic acid.- acidic urine inhibits stone formation in the kidneys. This will also prevent constipation to patient.

Protect from injury to prevent fracture. Normal saline IV.

- Ca excretion is promoted by Na excretion

NURSING MANAGEMENT Mobility- Mobility of the patient, with walking or use of

a rocking chair for those with limited mobility, is encouraged as much as possible because bones subjected to normal stress give up less calcium. Bedrest increases calcium excretion and the risk for renal calculi

NURSING MANAGEMENT Diet and Medication

- Low Ca diet- Antacid to peptic ulcer- Thiazide diuretics are avoided because they decrease the renal excretion of calcium and further elevate serum calcium levels.

HYPOPARATHYROIDISM The most common cause of

hypoparathyroidism is inadequate secretion of parathyroid hormone after interruption of the blood supply or surgical removal of parathyroid gland tissue during thyroidectomy, parathyroidectomy, or radical neck dissection.

PATHOPHYSIOLOGY

Surgical removal of Thyroid

hypocalcemia

Nervous systemIncreased neuroexcitability

Tingling in

fingers/Hyperactive reflexes

Skeletal Muscles

Muscle

spasm

Tetany

HeartWeak cardi

ac mucscle

contractio

nHypotension

GIT

Increased peristalsisDiarrhea

, nausea cramps

SIGNS AND SYMPTOMS Tetany is a general muscle hypertonia,

with tremor and spasmodic or uncoordinated contractions occurring with or without efforts to make voluntary movements.

Symptoms of latent tetany are numbness, tingling, and cramps in the extremities, and the patient complains of stiffness in the hands and feet.

SIGNS AND SYMPTOMS In overt tetany, the signs include

bronchospasm, laryngeal spasm, carpopedal spasm (flexion of the elbows and wrists and extension of the carpophalangeal joints), dysphagia, photophobia, cardiac dysrhythmias, and seizures.

Other symptoms include anxiety, irritability, depression, and even delirium. ECG changes and hypotension also may occur.

DIAGNOSTIC FINDINGS A positive Trousseau’s sign or a positive

Chvostek’s sign suggests latent tetany. Trousseau’s sign is positive when carpopedal spasm is induced by occluding the blood flow to the arm for 3 minutes with a blood pressure cuff. Chvostek’s sign is positive when a sharp tapping over the facial nerve just in front of the parotid gland and anterior to the ear causes spasm or twitching of the mouth, nose, and eye.

DIAGNOSTIC FINDINGS Tetany develops at calcium levels of 5 to

6 mg/dL (1.2 to 1.5 mmol/L) or lower. Serum phosphate levels are increased,

and x-rays of bone show increased density.

Calcification is detected on x-rays of the subcutaneous or paraspinal basal ganglia of the brain.

TREATMENT The goal of therapy is to raise the serum

calcium level to 9 to10 mg/dL (2.2 to 2.5 mmol/L) and to eliminate the symptoms of hypoparathyroidism and hypocalcemia.

If unrelieved, seizure may occur, Penobarbital may be given to sedate the patient.

Parenteral parathormone can be administered to treat acute hypoparathyroidism with tetany.

TREATMENT Tracheostomy or mechanical ventilation

may become necessary, along with bronchodilating medications, if the patient develops respiratory distress.

A diet high in calcium and low in phosphorus is prescribed. Although milk, milk products, and egg yolk are high in calcium, they are restricted because they also contain high levels of phosphorus.

TREATMENT Spinach also is avoided because it

contains oxalate, which would form insoluble calcium substances.

Oral tablets of calcium salts, such as calcium gluconate, may be used to supplement the diet. Aluminum hydroxide gel or aluminum carbonate (Gelusil, Amphojel) also is administered after meals to bind phosphate and promote its excretion through the gastrointestinal tract.

TREATMENT Vitamin D preparation—

dihydrotachysterol (AT 10 or Hytakerol), ergocalciferol (vitamin D), cholecalciferol (vitamin D)—are usually required and enhance calcium absorption from the gastrointestinal tract.

NURSING MANAGEMENT Care of postoperative patients

having thyroidectomy, parathyroidectomy, and radical neck dissection is directed toward detecting early signs of hypocalcemia and anticipating signs of tetany, seizures, and respiratory difficulties.

Prepare Tracheostomy set if Laryngospasm occurs.

NUESING MANAGEMENT Calcium gluconate is kept at the

bedside, with equipment necessary for intravenous administration. If the patient has a cardiac disorder, is subject to dysrhythmias, or is receiving digitalis, calcium gluconate is administered slowly and cautiously.Safety precautions for possible seizure

NURSING MANAGEMENT Calcium and digitalis increase systolic

contraction and also potentiate each other; this may produce potentially fatal dysrhythmias. Consequently, the cardiac patient requires continuous cardiac monitoring and careful assessment.

Safety precautions for possible seizure

THINK ABOUT THIS “ A bar of iron costs $5, made

into horseshoes its costs is $12, made into neddles its costs is $3,500, made into balance springs for watches, its worth is $300,000. Your value is developed as you go through refinement and fire of adversity.”