Four in number : 2 superior & 2 inferior
6mm in length
30-50mg each
b. Inferior parathyroid – situated in the lower pole
May also be supplied by: sup. thyroid artery
thyroid ima artery
laryngeal, tracheal & esophageal arteries.
Lymphatic Drainage:
Deep cervical & paratracheal L.N
Nerve Supply of parathyroid gland is derived from thyroid branches of cervical sympathetic ganglion.
DEVELOPMENT
-cells present are: chief cell ( contain lipid)
oxyphil cell
stromal, connective tissue and fat.
a.Etiology
Parathyroid adenoma (80%); may be associated with MEN I and II
Parathyroid hyperplasia (15%):
Diffuse enlargement of four glands
Usually composed of chief cells
Parathyroid carcinoma (very rare)
Paraneoplastic syndrome: lung and renal cell carcinomas
b. Pathogenesis: excess production of parathyroid hormone (PTH) leads to hypercalcemia
c.Clinical features
Often asymptomatic
Kidney stones
Osteoporosis and osteitis fibrosa cystica
Metastatic calcifications
Neurologic changes
i. Chronic renal failure
ii. Vitamin D deficiency
iii. Malabsorption
b. Pathogenesis: caused by any disease that results in hypocalcemia, leading to
increased secretion of PTH by the parathyroid glands
a. Etiology
i. Surgical removal of glands during thyroidectomy
ii. Di George syndrome
iii. Idiopathic
b. Clinical features
i. Lab: hypocalcemia
ii. Neuromuscular excitability and tetany: Chvostek's and Trousseau's signs
iii. Psychiatric disturbances
iv. Cardiac conduction defects (ECG: prolonged QT interval)
T/t: Vit D & Calcium
6mm in length
30-50mg each
Location:
a. Superior parathyroid- near the junction of inferior thyroid artery & rec. laryngeal nerve.b. Inferior parathyroid – situated in the lower pole
Blood Supply:
Branches of the inferior thyroid arteries.May also be supplied by: sup. thyroid artery
thyroid ima artery
laryngeal, tracheal & esophageal arteries.
Venous Drainage:
Parathyroid veins drain into thyroid plexus of veins of the thyroid gland and trachea.Lymphatic Drainage:
Deep cervical & paratracheal L.N
Nerve Supply of parathyroid gland is derived from thyroid branches of cervical sympathetic ganglion.
DEVELOPMENT
- Superior parathyroid from fourth pharyngeal pouch
- Inferior parathyroid from third pharyngeal pouch
- Parafollicular cells from ultimobranchial body ( 4th pharyngeal pouch)
HISTOLOGY
-capsule-cells present are: chief cell ( contain lipid)
oxyphil cell
stromal, connective tissue and fat.
FUNCTION
-PTH secretion : Calcium homeostasis
Primary hyperparathyroidism
a.Etiology
Parathyroid adenoma (80%); may be associated with MEN I and II
Parathyroid hyperplasia (15%):
Diffuse enlargement of four glands
Usually composed of chief cells
Parathyroid carcinoma (very rare)
Paraneoplastic syndrome: lung and renal cell carcinomas
b. Pathogenesis: excess production of parathyroid hormone (PTH) leads to hypercalcemia
c.Clinical features
Often asymptomatic
Kidney stones
Osteoporosis and osteitis fibrosa cystica
Metastatic calcifications
Neurologic changes
Secondary hyperparathyroidism
a. Etiologyi. Chronic renal failure
ii. Vitamin D deficiency
iii. Malabsorption
b. Pathogenesis: caused by any disease that results in hypocalcemia, leading to
increased secretion of PTH by the parathyroid glands
Hypoparathyroidism
a. Etiology
i. Surgical removal of glands during thyroidectomy
ii. Di George syndrome
iii. Idiopathic
b. Clinical features
i. Lab: hypocalcemia
ii. Neuromuscular excitability and tetany: Chvostek's and Trousseau's signs
iii. Psychiatric disturbances
iv. Cardiac conduction defects (ECG: prolonged QT interval)
T/t: Vit D & Calcium
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